Re: SX-110 Crystal Instability
Tried that. ?
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On Wed, Nov 2, 2022 at 10:20 AM, Richard Knoppow < 1oldlens1@...> wrote: I am not an expert but think this is not normal.? ?It looks like the crystal holder comes apart.? ?Perhaps cleaning crystal and electrodes will fix it.
-------- Original message -------- From: "KW4H via groups.io" <reedsteve@...> Date: 11/2/22 9:28 AM (GMT-08:00) Subject: [HallicraftersRadios] SX-110 Crystal Instability
Attached is a photo of the crystal in my SX-110.? I pulled the crystal to test its resonant frequency using a sig gen and scope, and the darn thing is so unstable it¡¯s driving me loopy.? The resonant frequency can vary (roughly) between 453.700 KHz and 453.800 KHz by simply moving it around, no matter how gently.? Pardon my ignorance, but is that normal for crystals of this vintage?? Is there a reason, operationally in the Hallicrafters, for a crystal to act like this?? Before I order a different (and more stable) crystal to solder into the circuit, thought I should ask. ? 73 ¨C Steve, KW4H ? ?
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Re: SX-110 Crystal Instability
I am not an expert but think this is not normal.? ?It looks like the crystal holder comes apart.? ?Perhaps cleaning crystal and electrodes will fix it.
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-------- Original message -------- From: "KW4H via groups.io" <reedsteve@...> Date: 11/2/22 9:28 AM (GMT-08:00) Subject: [HallicraftersRadios] SX-110 Crystal Instability
Attached is a photo of the crystal in my SX-110.? I pulled the crystal to test its resonant frequency using a sig gen and scope, and the darn thing is so unstable it¡¯s driving me loopy.? The resonant frequency can vary (roughly) between 453.700 KHz and 453.800 KHz by simply moving it around, no matter how gently.? Pardon my ignorance, but is that normal for crystals of this vintage?? Is there a reason, operationally in the Hallicrafters, for a crystal to act like this?? Before I order a different (and more stable) crystal to solder into the circuit, thought I should ask. ? 73 ¨C Steve, KW4H ? ?
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SX-110 Crystal Instability
Attached is a photo of the crystal in my SX-110.? I pulled the crystal to test its resonant frequency using a sig gen and scope, and the darn thing is so unstable it¡¯s driving me loopy.? The resonant frequency can vary (roughly) between 453.700 KHz and 453.800 KHz by simply moving it around, no matter how gently.? Pardon my ignorance, but is that normal for crystals of this vintage?? Is there a reason, operationally in the Hallicrafters, for a crystal to act like this?? Before I order a different (and more stable) crystal to solder into the circuit, thought I should ask. ? 73 ¨C Steve, KW4H ? ?
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Re: SX-71 Crystal Filter Alignment Woes
Hi Randy
Yes it was the converter.
???? I removed the transformer, and the top end cap and broken slug? pieces. The slug was broken where the lighter colored material meets the darker material , I carefully aligned the broken pieces and crazy glued them together. I lightly sanded the slug down
to fit smoothly in the tube, and I then switched it with the lower slug, thinking if the glue ever failed, the slug wouldn't fall like the top one did
Scott
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Thanks Scott. The subchassis sounds like it's the 2.0xx MHz converter. Did you try to repair the loose slug? If so, how did you do it?
I had a broken slug on my Sx-71, I discovered it because it would tune when upside down, and rite side up it wouldn't.
it was on the subchassis in the left rear.
Randy,
?
I¡¯ve been working on a SX-110, which uses the same type of instruction, and it¡¯s confusing and seems counter-intuitive for peaking the first IF transformer.? Once you¡¯ve identified the crystal frequency, you want to make sure that adjustment U is tuned for
the center of the DIP you found ¨C in other words, a MINIMUM of the beat note at the IF frequency.? At that point, the audio note will be much lower, and you¡¯ll hear much more of a ¡°swishing¡± sound than the beat note.? If you don¡¯t find it, then you turn adjustment
U a little bit one way or the other to try to bring the transformer into the range of the crystal frequency.
?
To find the crystal frequency, I connected a VTVM to the 500 ohm speaker output and put my signal generator into a slow sweep between 450 and 460 KHz.? Watching the VTVM, I found a beat note dip on the slope of one of the passes ¨C that got me into the ¡°ballpark¡±.?
I then stopped the sweep and set the generator for the approximate frequency where the dip was found, and then began manually adjusting the generator frequency in very small steps.? Once located (in my case, it was 453.48 KHz), I ¡°peaked¡± the transformer for
¡°minimum¡± beat note and maximum swishing sound.?
?
Honestly, I believe there are easier ways to find the actual crystal frequency.? The instruction in the manual is too much voodoo for my taste.? My SX-110 is a bit of a fun test radio, and one thing on my agenda (for today, in fact) was to simply discover the
crystal frequency by running the signal generator through it and monitoring for a peak on the oscilloscope.? The crystal will have maximum output at its resonant frequency.? Then, I¡¯ll try peaking up the 1st IF using that frequency, using a modulated
signal and with the BFO turned off.
?
73 ¨C Steve, KW4H
?
?
New to the forum and restoring an SX-71. I'm trying to go through the alignment procedure in the manual.
I'm stuck at Step 2 adjusting the IF coil associated with the 455 kHz crystal (adjusting tank U, aka T9 bottom).
I've watched some YouTubes on the topic, and most I've seen use a sweep generator and spectrum analyzer instead of the legacy Step 2 procedure.
I have an IFR 1200A but it doesn't have a sweep generator, so I attempted to do my adjustment per the manual. I've set the controls per the Step 2 instructions. Per my IFR 1200A the crystal seems to be at 457.9 kHz,
so that is what I'm generating with my IFR.
I was able to adjust tank U for a peak, but then I tried to look for dip & second peak on either side of the main peak, and couldn't seem to find it (I understand the adjustment goal is mid-way between the main peak
and the dip). At the main peak, adjusting the frequency +/- 100 Hz resulted in 40 dB drop.
Subsequently, I tried to adjust again for the former peak, but this time the best peak I could get was about???of what I had before, and when 100 Hz off center freq, the drop is far less dramatic.
I fear that I dislodged the ferrite slug from the adjustment screw by going too far one way or the other.
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I have a truly collector condition SX-71 and matching speaker for sale in central MD. It is the version w/o 15m calibration (use the logging scale).? Downsizing the collection, here, for better or worse.? Demo and pick-up only. $190, includes book and custom windowed dust cover. TNX.
Jeep K3HVG
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Re: What's Old, is New Again - Hallicrafters SX-17 & FT8
Good luck with yours.
Edit: What is interesting, using the FT8 audio scale, you can measure your receiver drift in cycles and its direction, up or down.
Who knew, FT8 could be used as a quasi diagnostic tool.
K2WH
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Re: What's Old, is New Again - Hallicrafters SX-17 & FT8
Good to hear that, Bill. I hope to be able to do that with my 1937 SX16 whenever I manage to get it restored!
Peter, G4ADJ?
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Re: SX-71 Crystal Filter Alignment Woes
Thanks Scott. The subchassis sounds like it's the 2.0xx MHz converter. Did you try to repair the loose slug? If so, how did you do it?
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I had a broken slug on my Sx-71, I discovered it because it would tune when upside down, and rite side up it wouldn't.
it was on the subchassis in the left rear.
Randy,
?
I¡¯ve been working on a SX-110, which uses the same type of instruction, and it¡¯s confusing and seems counter-intuitive for peaking the first IF transformer.? Once you¡¯ve identified the crystal frequency, you want to make sure that adjustment U is tuned for
the center of the DIP you found ¨C in other words, a MINIMUM of the beat note at the IF frequency.? At that point, the audio note will be much lower, and you¡¯ll hear much more of a ¡°swishing¡± sound than the beat note.? If you don¡¯t find it, then you turn adjustment
U a little bit one way or the other to try to bring the transformer into the range of the crystal frequency.
?
To find the crystal frequency, I connected a VTVM to the 500 ohm speaker output and put my signal generator into a slow sweep between 450 and 460 KHz.? Watching the VTVM, I found a beat note dip on the slope of one of the passes ¨C that got me into the ¡°ballpark¡±.?
I then stopped the sweep and set the generator for the approximate frequency where the dip was found, and then began manually adjusting the generator frequency in very small steps.? Once located (in my case, it was 453.48 KHz), I ¡°peaked¡± the transformer for
¡°minimum¡± beat note and maximum swishing sound.?
?
Honestly, I believe there are easier ways to find the actual crystal frequency.? The instruction in the manual is too much voodoo for my taste.? My SX-110 is a bit of a fun test radio, and one thing on my agenda (for today, in fact) was to simply discover the
crystal frequency by running the signal generator through it and monitoring for a peak on the oscilloscope.? The crystal will have maximum output at its resonant frequency.? Then, I¡¯ll try peaking up the 1st IF using that frequency, using a modulated
signal and with the BFO turned off.
?
73 ¨C Steve, KW4H
?
?
New to the forum and restoring an SX-71. I'm trying to go through the alignment procedure in the manual.
I'm stuck at Step 2 adjusting the IF coil associated with the 455 kHz crystal (adjusting tank U, aka T9 bottom).
I've watched some YouTubes on the topic, and most I've seen use a sweep generator and spectrum analyzer instead of the legacy Step 2 procedure.
I have an IFR 1200A but it doesn't have a sweep generator, so I attempted to do my adjustment per the manual. I've set the controls per the Step 2 instructions. Per my IFR 1200A the crystal seems to be at 457.9 kHz,
so that is what I'm generating with my IFR.
I was able to adjust tank U for a peak, but then I tried to look for dip & second peak on either side of the main peak, and couldn't seem to find it (I understand the adjustment goal is mid-way between the main peak
and the dip). At the main peak, adjusting the frequency +/- 100 Hz resulted in 40 dB drop.
Subsequently, I tried to adjust again for the former peak, but this time the best peak I could get was about???of what I had before, and when 100 Hz off center freq, the drop is far less dramatic.
I fear that I dislodged the ferrite slug from the adjustment screw by going too far one way or the other.
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Re: SX-71 Crystal Filter Alignment Woes
I had a broken slug on my Sx-71, I discovered it because it would tune when upside down, and rite side up it wouldn't.
it was on the subchassis in the left rear.
toggle quoted message
Show quoted text
Randy,
?
I¡¯ve been working on a SX-110, which uses the same type of instruction, and it¡¯s confusing and seems counter-intuitive for peaking the first IF transformer.? Once you¡¯ve identified the crystal frequency, you want to make sure that adjustment U is tuned for
the center of the DIP you found ¨C in other words, a MINIMUM of the beat note at the IF frequency.? At that point, the audio note will be much lower, and you¡¯ll hear much more of a ¡°swishing¡± sound than the beat note.? If you don¡¯t find it, then you turn adjustment
U a little bit one way or the other to try to bring the transformer into the range of the crystal frequency.
?
To find the crystal frequency, I connected a VTVM to the 500 ohm speaker output and put my signal generator into a slow sweep between 450 and 460 KHz.? Watching the VTVM, I found a beat note dip on the slope of one of the passes ¨C that got me into the ¡°ballpark¡±.?
I then stopped the sweep and set the generator for the approximate frequency where the dip was found, and then began manually adjusting the generator frequency in very small steps.? Once located (in my case, it was 453.48 KHz), I ¡°peaked¡± the transformer for
¡°minimum¡± beat note and maximum swishing sound.?
?
Honestly, I believe there are easier ways to find the actual crystal frequency.? The instruction in the manual is too much voodoo for my taste.? My SX-110 is a bit of a fun test radio, and one thing on my agenda (for today, in fact) was to simply discover the
crystal frequency by running the signal generator through it and monitoring for a peak on the oscilloscope.? The crystal will have maximum output at its resonant frequency.? Then, I¡¯ll try peaking up the 1st IF using that frequency, using a modulated
signal and with the BFO turned off.
?
73 ¨C Steve, KW4H
?
?
New to the forum and restoring an SX-71. I'm trying to go through the alignment procedure in the manual.
I'm stuck at Step 2 adjusting the IF coil associated with the 455 kHz crystal (adjusting tank U, aka T9 bottom).
I've watched some YouTubes on the topic, and most I've seen use a sweep generator and spectrum analyzer instead of the legacy Step 2 procedure.
I have an IFR 1200A but it doesn't have a sweep generator, so I attempted to do my adjustment per the manual. I've set the controls per the Step 2 instructions. Per my IFR 1200A the crystal seems to be at 457.9 kHz,
so that is what I'm generating with my IFR.
I was able to adjust tank U for a peak, but then I tried to look for dip & second peak on either side of the main peak, and couldn't seem to find it (I understand the adjustment goal is mid-way between the main peak
and the dip). At the main peak, adjusting the frequency +/- 100 Hz resulted in 40 dB drop.
Subsequently, I tried to adjust again for the former peak, but this time the best peak I could get was about???of what I had before, and when 100 Hz off center freq, the drop is far less dramatic.
I fear that I dislodged the ferrite slug from the adjustment screw by going too far one way or the other.
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What's Old, is New Again - Hallicrafters SX-17 & FT8
Been using my SX-17 to cruise around the SW bands, haven't done that in some time but out of curiosity, I wanted to see if it? was possible to decode FT8 using acoustical coupling, from the SX-17 speaker on the other side of the room to the mic in my laptop..
I was gratified that yes, it is possible to decode 2022 FT8 signals via acoustical coupling from a 1939 vacuum tube SW receiver, a whole 83 years later.
Of course, this was after ~ 1 hour of warm up, prior to the attempt.
K2WH
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Re: SX-71 Crystal Filter Alignment Woes
Forgot to mention ¨C it will be interesting to see if the 453.48 MHz frequency I allegedly ¡°located¡± on that dip is, in fact, the actual frequency of the crystal ¨C and if the 1st IF is already properly peaked using the method in the Hallicrafters manual.? I¡¯ll post the results later today.? ? Interestingly, National uses a similar ¡°find the crystal frequency¡± game in its IF alignment for the HRO-60, but it¡¯s the peak they want.? The setup is similar ¨C signal generator to the mixer section of the main tuning capacitor, and a VTVM on the audio output.? Turn on the BFO and adjust for some beat note between 400 and 1000 Hz, and then vary the tuning control of the signal generator very slowly until a peak is found on the meter.? That, per National, is the frequency of the crystal.? Interesting how Hallicrafters has you do the same thing, but they¡¯re looking for a dip on the slope.? Huh?? Anyone have comments on that? ? Like I said, it will be interesting to see what¡¯s really going on. ? 73 ¨C Steve, KW4H ? Randy, ? I¡¯ve been working on a SX-110, which uses the same type of instruction, and it¡¯s confusing and seems counter-intuitive for peaking the first IF transformer.? Once you¡¯ve identified the crystal frequency, you want to make sure that adjustment U is tuned for the center of the DIP you found ¨C in other words, a MINIMUM of the beat note at the IF frequency.? At that point, the audio note will be much lower, and you¡¯ll hear much more of a ¡°swishing¡± sound than the beat note.? If you don¡¯t find it, then you turn adjustment U a little bit one way or the other to try to bring the transformer into the range of the crystal frequency. ? To find the crystal frequency, I connected a VTVM to the 500 ohm speaker output and put my signal generator into a slow sweep between 450 and 460 KHz.? Watching the VTVM, I found a beat note dip on the slope of one of the passes ¨C that got me into the ¡°ballpark¡±.? I then stopped the sweep and set the generator for the approximate frequency where the dip was found, and then began manually adjusting the generator frequency in very small steps.? Once located (in my case, it was 453.48 KHz), I ¡°peaked¡± the transformer for ¡°minimum¡± beat note and maximum swishing sound.? ? Honestly, I believe there are easier ways to find the actual crystal frequency.? The instruction in the manual is too much voodoo for my taste.? My SX-110 is a bit of a fun test radio, and one thing on my agenda (for today, in fact) was to simply discover the crystal frequency by running the signal generator through it and monitoring for a peak on the oscilloscope.? The crystal will have maximum output at its resonant frequency.? Then, I¡¯ll try peaking up the 1st IF using that frequency, using a modulated signal and with the BFO turned off. ? 73 ¨C Steve, KW4H ? ? New to the forum and restoring an SX-71. I'm trying to go through the alignment procedure in the manual. I'm stuck at Step 2 adjusting the IF coil associated with the 455 kHz crystal (adjusting tank U, aka T9 bottom). I've watched some YouTubes on the topic, and most I've seen use a sweep generator and spectrum analyzer instead of the legacy Step 2 procedure. I have an IFR 1200A but it doesn't have a sweep generator, so I attempted to do my adjustment per the manual. I've set the controls per the Step 2 instructions. Per my IFR 1200A the crystal seems to be at 457.9 kHz, so that is what I'm generating with my IFR. I was able to adjust tank U for a peak, but then I tried to look for dip & second peak on either side of the main peak, and couldn't seem to find it (I understand the adjustment goal is mid-way between the main peak and the dip). At the main peak, adjusting the frequency +/- 100 Hz resulted in 40 dB drop. Subsequently, I tried to adjust again for the former peak, but this time the best peak I could get was about???of what I had before, and when 100 Hz off center freq, the drop is far less dramatic. I fear that I dislodged the ferrite slug from the adjustment screw by going too far one way or the other.
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Re: SX-71 Crystal Filter Alignment Woes
Randy, ? I¡¯ve been working on a SX-110, which uses the same type of instruction, and it¡¯s confusing and seems counter-intuitive for peaking the first IF transformer.? Once you¡¯ve identified the crystal frequency, you want to make sure that adjustment U is tuned for the center of the DIP you found ¨C in other words, a MINIMUM of the beat note at the IF frequency.? At that point, the audio note will be much lower, and you¡¯ll hear much more of a ¡°swishing¡± sound than the beat note.? If you don¡¯t find it, then you turn adjustment U a little bit one way or the other to try to bring the transformer into the range of the crystal frequency. ? To find the crystal frequency, I connected a VTVM to the 500 ohm speaker output and put my signal generator into a slow sweep between 450 and 460 KHz.? Watching the VTVM, I found a beat note dip on the slope of one of the passes ¨C that got me into the ¡°ballpark¡±.? I then stopped the sweep and set the generator for the approximate frequency where the dip was found, and then began manually adjusting the generator frequency in very small steps.? Once located (in my case, it was 453.48 KHz), I ¡°peaked¡± the transformer for ¡°minimum¡± beat note and maximum swishing sound.? ? Honestly, I believe there are easier ways to find the actual crystal frequency.? The instruction in the manual is too much voodoo for my taste.? My SX-110 is a bit of a fun test radio, and one thing on my agenda (for today, in fact) was to simply discover the crystal frequency by running the signal generator through it and monitoring for a peak on the oscilloscope.? The crystal will have maximum output at its resonant frequency.? Then, I¡¯ll try peaking up the 1st IF using that frequency, using a modulated signal and with the BFO turned off. ? 73 ¨C Steve, KW4H ? ? New to the forum and restoring an SX-71. I'm trying to go through the alignment procedure in the manual. I'm stuck at Step 2 adjusting the IF coil associated with the 455 kHz crystal (adjusting tank U, aka T9 bottom). I've watched some YouTubes on the topic, and most I've seen use a sweep generator and spectrum analyzer instead of the legacy Step 2 procedure. I have an IFR 1200A but it doesn't have a sweep generator, so I attempted to do my adjustment per the manual. I've set the controls per the Step 2 instructions. Per my IFR 1200A the crystal seems to be at 457.9 kHz, so that is what I'm generating with my IFR. I was able to adjust tank U for a peak, but then I tried to look for dip & second peak on either side of the main peak, and couldn't seem to find it (I understand the adjustment goal is mid-way between the main peak and the dip). At the main peak, adjusting the frequency +/- 100 Hz resulted in 40 dB drop. Subsequently, I tried to adjust again for the former peak, but this time the best peak I could get was about???of what I had before, and when 100 Hz off center freq, the drop is far less dramatic. I fear that I dislodged the ferrite slug from the adjustment screw by going too far one way or the other.
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SX-71 Crystal Filter Alignment Woes
New to the forum and restoring an SX-71. I'm trying to go through the alignment procedure in the manual.
I'm stuck at Step 2 adjusting the IF coil associated with the 455 kHz crystal (adjusting tank U, aka T9 bottom).
I've watched some YouTubes on the topic, and most I've seen use a sweep generator and spectrum analyzer instead of the legacy Step 2 procedure.
I have an IFR 1200A but it doesn't have a sweep generator, so I attempted to do my adjustment per the manual. I've set the controls per the Step 2 instructions. Per my IFR 1200A the crystal seems to be at 457.9 kHz, so that is what I'm generating with my IFR.
I was able to adjust tank U for a peak, but then I tried to look for dip & second peak on either side of the main peak, and couldn't seem to find it (I understand the adjustment goal is mid-way between the main peak and the dip). At the main peak, adjusting
the frequency +/- 100 Hz resulted in 40 dB drop.
Subsequently, I tried to adjust again for the former peak, but this time the best peak I could get was about???of what I had before, and when 100 Hz off center freq, the drop is far less dramatic.
I fear that I dislodged the ferrite slug from the adjustment screw by going too far one way or the other.
Any ideas?
Thanks,
Randy, W7HMT
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Re: SX-110 2nd IF Circuit Design
The links were to worldradiohistory.org This site has a perfectly enormous collection of stuff on it .? I suggest exploring.? QST is on the ARRL site but I believe one must be a member to access the archive.
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-------- Original message -------- From: don Root <drootofallevil@...> Date: 10/31/22 6:25 PM (GMT-08:00) Subject: Re: [HallicraftersRadios] SX-110 2nd IF Circuit Design
Hi Richard ?and friends too I don¡¯t know where they reside other than somewhere in the clouds. ?I just put ¡°qst 1946¡± into google and that¡¯s what I got ¡Oct came first and amazing there was the 42. Just lucky for once, or google knew I was going to look inside for a Halli 42 ?due to a flurry of previous requests I did not look in detail in Dec issue ; Ilooked only about july to dec 46? ,, no doubt there is more in 47 but if found? what I wanted The QST early pics have the R-42 , not the pm-23 that somebody Steve? Said was in radio news. I thought QST was part of ARRL and ?i almost signed up to ARRL, a while back but they demanded to know more than the government and ?all the banks and the depth of my pants pockets ! ?¡So I hit the top right X ? I will sneak this in here, but my understanding is that it receives AM , and CW all the way to the top, leaving a question, I guess a mode switch must be able to direct 88.1 Mc to either 10.7 Mc fm or 455 kc AM/cw ..dunno yet Don VA3DRL ? ? ? The last one has 8 pages on the receiver and I didn't count but at least 30 cooperative dealer ads featuring it.? Hallicrafters was really pushing it.?? BTW a really thick edition ? A reaction to war time restrictions.? ?Also note the prices and compare them in about a year? ? With the elimination of ear time regulations the inflation makes our current problem look miniscule.? Also,? am I imagining it or are these scans better than those on the ARRL. Site?
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Re: SX-110 2nd IF Circuit Design
Hi Richard ?and friends too I don¡¯t know where they reside other than somewhere in the clouds. ?I just put ¡°qst 1946¡± into google and that¡¯s what I got ¡Oct came first and amazing there was the 42. Just lucky for once, or google knew I was going to look inside for a Halli 42 ?due to a flurry of previous requests I did not look in detail in Dec issue ; Ilooked only about july to dec 46? ,, no doubt there is more in 47 but if found? what I wanted The QST early pics have the R-42 , not the pm-23 that somebody Steve? Said was in radio news. I thought QST was part of ARRL and ?i almost signed up to ARRL, a while back but they demanded to know more than the government and ?all the banks and the depth of my pants pockets ! ?¡So I hit the top right X ? I will sneak this in here, but my understanding is that it receives AM , and CW all the way to the top, leaving a question, I guess a mode switch must be able to direct 88.1 Mc to either 10.7 Mc fm or 455 kc AM/cw ..dunno yet Don VA3DRL ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Richard Knoppow
Sent: Monday, October 31, 2022 8:39 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-110 2nd IF Circuit Design? The last one has 8 pages on the receiver and I didn't count but at least 30 cooperative dealer ads featuring it.? Hallicrafters was really pushing it.?? BTW a really thick edition ? A reaction to war time restrictions.? ?Also note the prices and compare them in about a year? ? With the elimination of ear time regulations the inflation makes our current problem look miniscule.? Also,? am I imagining it or are these scans better than those on the ARRL. Site?
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Re: SX-110 2nd IF Circuit Design
The last one has 8 pages on the receiver and I didn't count but at least 30 cooperative dealer ads featuring it.? Hallicrafters was really pushing it.?? BTW a really thick edition ? A reaction to war time restrictions.? ?Also note the prices and compare them in about a year? ? With the elimination of ear time regulations the inflation makes our current problem look miniscule.? Also,? am I imagining it or are these scans better than those on the ARRL. Site?
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Re: SX-110 2nd IF Circuit Design
Steve; and dedicated followers; I see no indication of variations or changes to the 42 in MY second edition Ostermans or in MY Dachis 1996 printing. They managed to find the later revision info to list for the receiver tube functions. I did see that FM ?went from 27 to 110 MHz [but ?I¡¯ll bet the dial is in ¡°Mcees¡±] allowing the SX-42 to do old and new FM bands Seems to me I read somewhere about the 6th band but? my take was that by production time, there were 6 bands so that was fixed. ? I just ran into the June 47 service bulletin on BAMA and on the ?first page under TUBE TYPES AND FUNCTIONS, it says for the first 7h7 ?¡°1st f-m limiter amplifier¡± ?, the other is? ¡°2nd f-m limiter-amplifier¡± ???but the schematic strips the ¡°f-m¡± and the ¡°amplifier¡± leaving only ¡°limiter¡± Old or not there should be a hint here. Richard¡¯s comment just arrived now, as to first produced year, I see both Dachis and Osterman showing 1947, and the first manual I have seen says January 1947 at the top. What I have seen on BAMA information has no 1946 dates, so I looked in QST and near the top found Halli adds: Sept 46 and before see s-38 and s-40 no sx -42 then Oct 46 ..Sx 42 first add ?I found in qst ?coming soon? look at the first simple sketches ??? nov 46? says first reviews ??? dec 46? first indication that it is/WILL BE ?is for sale? ..seems to be available ??? so other than the early test units it must have been 1947 before any consumer units ?went out the door, but it is close. We can wonder if any of those 1946 early units are around ? Seems we are off-topic again a bit Don VA3DRL ?
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From: [email protected] [mailto:[email protected]] On Behalf Of KW4H via groups.io
Sent: Monday, October 31, 2022 5:18 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-110 2nd IF Circuit Design? On the SX-42:? Osterman¡¯s book indicates that there were several circuit changes during the production years of this model.? One of the back stories appears to be what happened with FM radio.? From 1936-46, FM was in the 42 ¨C 50 Mhz band.? However, the FCC required FM stations to move to the new frequencies of 88 ¨C 108 MHz by 1948.? In response, Hallicrafters added a sixth band, to bring the coverage up to 110 MHz.? What¡¯s really confusing is that the model number stayed exactly the same despite all the circuit changes. ? 73 ¨C Steve, KW4H
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Re: SX-110 2nd IF Circuit Design
Per the Osterman book, the SX-42 was on the market from 1947 ¨C 1950.? However, information on another site shows that it was advertised as far back as the December ¡¯46 issue of Radio News (see attached).? AND ¨C looking at the 1946 advertisement, the advertised frequency range was 540 kc to 110 MHz!? Therefore, my hypothesis was entirely incorrect.? Disclaimer:? I was born in ¡¯59 and didn¡¯t get into SWL¡¯ing until I was about 12 years old ¨C so I rely on online sources for historical information.? The site that stated that Hallicrafters added the higher frequency range later wasn¡¯t exactly correct.? Anyway, Osterman states that there were circuit changes during the life of the SX-42.? Have a look at this site: ? ? 73 ¨C Steve, KW4H ? When did the SX 42 come on the market?? Hallicrafters advertised it as the first really new post war receiver.? FM broadcasting began experimentally in 1936 according to FCC records .? By 1946 there were about 25 stations.? The FCC decided to move the FM band to 88 to 108 mhz starting in 1946, requiring all existing stations to change by 1948.? Evidently both bands were in use during the changeover period.? So, if the SX 42 was released in 1946 it likely accommodated both bands. Since the change had been proposed and discussed for some time in advance it seems unlikely many receivers were made without the new band.? They would have been obsolete immediately.? May some.prototypes were made.? It's interesting thT the S 36 covered both bands although the high band was not assigned to broadcasting at the time. The history of FM is filled with controversy.? ?Makes interesting reading.? FM was not profitable until the introduction of compatible stereo and the FCC regulation requiring dual AM/FM receivers .? There was just not a large enough potential audience to support it.
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-------- Original message --------From: "KW4H via groups.io" <reedsteve@...> Date: 10/31/22 2:18 PM (GMT-08:00) Subject: Re: [HallicraftersRadios] SX-110 2nd IF Circuit Design On the SX-42:? Osterman¡¯s book indicates that there were several circuit changes during the production years of this model.? One of the back stories appears to be what happened with FM radio.? From 1936-46, FM was in the 42 ¨C 50 Mhz band.? However, the FCC required FM stations to move to the new frequencies of 88 ¨C 108 MHz by 1948.? In response, Hallicrafters added a sixth band, to bring the coverage up to 110 MHz.? What¡¯s really confusing is that the model number stayed exactly the same despite all the circuit changes. ? 73 ¨C Steve, KW4H ? Jacques; Holy Moly! as we used to say, no wonder we? are in no-mans¡¯ land. Continuing the SX-42 diversion¡I saw some of the detailed changes sheets on the BAMA site ?too, and they seem to address much of this. It seems clear that at some point there were significant changes beginning at the secondary of the 3rd IF transformer and ongoing, and the major rev must be adding that switch so that both the AM and FM go thru the first 7H7, whatever it is really doing. Wonder why the change/changes?? Makes one think the original circuit did not have enough amplification on AM. ?? I am still trying to make sense of the circuit; is ?the 7H7 really amplifying or what? Getting back to Sterves Original question about why one tube, not the other: One wonders Why use a Loctal when most are octals? The S-47 uses a 6SG7 in the same spot? but is called ??¡°FM 3RD IF AMP ¨CAM DET¡± and it is produced at the same time. How is your band switch doing? Don VA3DRL ? ? Hi Don, ? The different produced versions of the SX-42 made me scratch my head big time¡ Let¡¯s say that in the first versions (according to the schematic 89D210) the first 7H7 is identified as a ¡°1st ±ô¾±³¾¾±³Ù±ð°ù¡±. Probably because it is used only for the 10.7 MHz IF signal and then feeds the 2nd 7H7 tube identified as the ¡°2nd limiter and 10.7 MHz AM detector¡±. The 455 kHz signal from the 3rd IF transformer is not coupled to the 1st 7H7 but applied to half of a 6H6 used as a detector, the other half of the same tube supporting the Noise Limiter function. ? In the late production versions (according to the 89D257 schematic) both the 455 kHz and 10.7 MHz signals are applied to the first 7H7 tube grid, and it¡¯s designation was changed to ¡°3rd ±õ¹ó¡±. Both 455 kHz and 10.7 MHz AM signals are then ¡°detected¡± by the second 7H7 tube (control grid to cathode) and the right part of the 6H6, used as a detector in the first versions, is completely disconnected. ? And A LOT of components values and circuitry topology changed between the first and the last SX-42 made. The one I restored last spring was something of a mix between the first and the last versions already (stamped May 12, 1947) and was more or less conform to the XXXX production run, so I decided to rebuild it to be compliant to the schematic 89D257E. ? Let¡¯s figure here that there was 20 engineering changes applied successively to the production runs X, XX, XXX, XXXX and 1, updating the related schematics from 89D210 to 89D210K. Then the 89D257 come, with more engineering changes creating versions from A to G. The 89D257F required a change to the SW 1 (the Band switch), sections K and KK, and this is why I had not been able to implement this one. But the Rev. G change, which added a 6.8 ohms resistor (R108) in series with the 6H6 noise limiter heater was doable. ? At the end, I do not know if my own ¡°version¡± of the SX-42 work better (or worse) than any other¡ But, at least, it works on all bands and modes ! ? 73, Jacques, VE2JFE in Montreal ? Jacques ?and the gang Do you/we believe that an early version of the schematic was much the same as later versions BUT the old drawing was in error by calling the 7H7 a Limiter, when all the time it was an IF amp? don
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Re: SX-110 2nd IF Circuit Design
When did the SX 42 come on the market?? Hallicrafters advertised it as the first really new post war receiver.? FM broadcasting began experimentally in 1936 according to FCC records .? By 1946 there were about 25 stations.? The FCC decided to move the FM band to 88 to 108 mhz starting in 1946, requiring all existing stations to change by 1948.? Evidently both bands were in use during the changeover period.? So, if the SX 42 was released in 1946 it likely accommodated both bands. Since the change had been proposed and discussed for some time in advance it seems unlikely many receivers were made without the new band.? They would have been obsolete immediately.? May some.prototypes were made.? It's interesting thT the S 36 covered both bands although the high band was not assigned to broadcasting at the time. The history of FM is filled with controversy.? ?Makes interesting reading.? FM was not profitable until the introduction of compatible stereo and the FCC regulation requiring dual AM/FM receivers .? There was just not a large enough potential audience to support it.
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-------- Original message -------- From: "KW4H via groups.io" <reedsteve@...> Date: 10/31/22 2:18 PM (GMT-08:00) Subject: Re: [HallicraftersRadios] SX-110 2nd IF Circuit Design
On the SX-42:? Osterman¡¯s book indicates that there were several circuit changes during the production years of this model.? One of the back stories appears to be what happened with FM radio.? From 1936-46, FM was in the 42 ¨C 50 Mhz band.? However, the FCC required FM stations to move to the new frequencies of 88 ¨C 108 MHz by 1948.? In response, Hallicrafters added a sixth band, to bring the coverage up to 110 MHz.? What¡¯s really confusing is that the model number stayed exactly the same despite all the circuit changes. ? 73 ¨C Steve, KW4H ? Jacques; Holy Moly! as we used to say, no wonder we? are in no-mans¡¯ land. Continuing the SX-42 diversion¡I saw some of the detailed changes sheets on the BAMA site ?too, and they seem to address much of this. It seems clear that at some point there were significant changes beginning at the secondary of the 3rd IF transformer and ongoing, and the major rev must be adding that switch so that both the AM and FM go thru the first 7H7, whatever it is really doing. Wonder why the change/changes?? Makes one think the original circuit did not have enough amplification on AM. ?? I am still trying to make sense of the circuit; is ?the 7H7 really amplifying or what? Getting back to Sterves Original question about why one tube, not the other: One wonders Why use a Loctal when most are octals? The S-47 uses a 6SG7 in the same spot? but is called ??¡°FM 3RD IF AMP ¨CAM DET¡± and it is produced at the same time. How is your band switch doing? Don VA3DRL ? ? Hi Don, ? The different produced versions of the SX-42 made me scratch my head big time¡ Let¡¯s say that in the first versions (according to the schematic 89D210) the first 7H7 is identified as a ¡°1st ±ô¾±³¾¾±³Ù±ð°ù¡±. Probably because it is used only for the 10.7 MHz IF signal and then feeds the 2nd 7H7 tube identified as the ¡°2nd limiter and 10.7 MHz AM detector¡±. The 455 kHz signal from the 3rd IF transformer is not coupled to the 1st 7H7 but applied to half of a 6H6 used as a detector, the other half of the same tube supporting the Noise Limiter function. ? In the late production versions (according to the 89D257 schematic) both the 455 kHz and 10.7 MHz signals are applied to the first 7H7 tube grid, and it¡¯s designation was changed to ¡°3rd ±õ¹ó¡±. Both 455 kHz and 10.7 MHz AM signals are then ¡°detected¡± by the second 7H7 tube (control grid to cathode) and the right part of the 6H6, used as a detector in the first versions, is completely disconnected. ? And A LOT of components values and circuitry topology changed between the first and the last SX-42 made. The one I restored last spring was something of a mix between the first and the last versions already (stamped May 12, 1947) and was more or less conform to the XXXX production run, so I decided to rebuild it to be compliant to the schematic 89D257E. ? Let¡¯s figure here that there was 20 engineering changes applied successively to the production runs X, XX, XXX, XXXX and 1, updating the related schematics from 89D210 to 89D210K. Then the 89D257 come, with more engineering changes creating versions from A to G. The 89D257F required a change to the SW 1 (the Band switch), sections K and KK, and this is why I had not been able to implement this one. But the Rev. G change, which added a 6.8 ohms resistor (R108) in series with the 6H6 noise limiter heater was doable. ? At the end, I do not know if my own ¡°version¡± of the SX-42 work better (or worse) than any other¡ But, at least, it works on all bands and modes ! ? 73, Jacques, VE2JFE in Montreal ? Jacques ?and the gang Do you/we believe that an early version of the schematic was much the same as later versions BUT the old drawing was in error by calling the 7H7 a Limiter, when all the time it was an IF amp? don
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Re: SX-110 2nd IF Circuit Design
On the SX-42:? Osterman¡¯s book indicates that there were several circuit changes during the production years of this model.? One of the back stories appears to be what happened with FM radio.? From 1936-46, FM was in the 42 ¨C 50 Mhz band.? However, the FCC required FM stations to move to the new frequencies of 88 ¨C 108 MHz by 1948.? In response, Hallicrafters added a sixth band, to bring the coverage up to 110 MHz.? What¡¯s really confusing is that the model number stayed exactly the same despite all the circuit changes. ? 73 ¨C Steve, KW4H ? Jacques; Holy Moly! as we used to say, no wonder we? are in no-mans¡¯ land. Continuing the SX-42 diversion¡I saw some of the detailed changes sheets on the BAMA site ?too, and they seem to address much of this. It seems clear that at some point there were significant changes beginning at the secondary of the 3rd IF transformer and ongoing, and the major rev must be adding that switch so that both the AM and FM go thru the first 7H7, whatever it is really doing. Wonder why the change/changes?? Makes one think the original circuit did not have enough amplification on AM. ?? I am still trying to make sense of the circuit; is ?the 7H7 really amplifying or what? Getting back to Sterves Original question about why one tube, not the other: One wonders Why use a Loctal when most are octals? The S-47 uses a 6SG7 in the same spot? but is called ??¡°FM 3RD IF AMP ¨CAM DET¡± and it is produced at the same time. How is your band switch doing? Don VA3DRL ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jacques_VE2JFE
Sent: Monday, October 31, 2022 12:21 AM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-110 2nd IF Circuit Design
Importance: High? Hi Don, ? The different produced versions of the SX-42 made me scratch my head big time¡ Let¡¯s say that in the first versions (according to the schematic 89D210) the first 7H7 is identified as a ¡°1st ±ô¾±³¾¾±³Ù±ð°ù¡±. Probably because it is used only for the 10.7 MHz IF signal and then feeds the 2nd 7H7 tube identified as the ¡°2nd limiter and 10.7 MHz AM detector¡±. The 455 kHz signal from the 3rd IF transformer is not coupled to the 1st 7H7 but applied to half of a 6H6 used as a detector, the other half of the same tube supporting the Noise Limiter function. ? In the late production versions (according to the 89D257 schematic) both the 455 kHz and 10.7 MHz signals are applied to the first 7H7 tube grid, and it¡¯s designation was changed to ¡°3rd ±õ¹ó¡±. Both 455 kHz and 10.7 MHz AM signals are then ¡°detected¡± by the second 7H7 tube (control grid to cathode) and the right part of the 6H6, used as a detector in the first versions, is completely disconnected. ? And A LOT of components values and circuitry topology changed between the first and the last SX-42 made. The one I restored last spring was something of a mix between the first and the last versions already (stamped May 12, 1947) and was more or less conform to the XXXX production run, so I decided to rebuild it to be compliant to the schematic 89D257E. ? Let¡¯s figure here that there was 20 engineering changes applied successively to the production runs X, XX, XXX, XXXX and 1, updating the related schematics from 89D210 to 89D210K. Then the 89D257 come, with more engineering changes creating versions from A to G. The 89D257F required a change to the SW 1 (the Band switch), sections K and KK, and this is why I had not been able to implement this one. But the Rev. G change, which added a 6.8 ohms resistor (R108) in series with the 6H6 noise limiter heater was doable. ? At the end, I do not know if my own ¡°version¡± of the SX-42 work better (or worse) than any other¡ But, at least, it works on all bands and modes ! ? 73, Jacques, VE2JFE in Montreal ? Jacques ?and the gang Do you/we believe that an early version of the schematic was much the same as later versions BUT the old drawing was in error by calling the 7H7 a Limiter, when all the time it was an IF amp? don
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Bill (Group Owner)
Randy - W7HMT - North Bend WA
don Root