Re: SX-110 Crystal Instability
Sounds cool!? All I’ve been doing here is just the old-fashioned signal generator and oscilloscope method.? The resonant frequency is the peak.? It’s always worked well for me…until…this crystal.? All you have to do is just gently pick up the crystal and set it down again, and the resonant frequency changes.? ? 73 – Steve, KW4H ? This is perhaps your test? configuration Steve. I have made? jigs with the? crystal socket and a PCB ?that then plugs into?? my VNA. I would think you could make a jog with shielded? cables and rigid connectors. Just be aware that cable capacity? will likely alter the resonant frequency. ? Regards, Dale W4OP ?
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From: [email protected] [mailto:[email protected]] On Behalf Of KW4H via groups.io
Sent: Wednesday, November 2, 2022 2:49 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-110 Crystal Instability? Yeah, I ordered a couple of 455 KHz crystals today.? It would be good to have another on hand.? ? FYI, I stumble onto these things because I restore boat anchors (mostly receivers) for educational and historical purposes.? I also write articles for ER magazine, and the extra information is fun and interesting.? Anyway, I’m more likely to remove a component and test it out of curiosity rather than questioning the design.? The unstable crystal caught me by surprise! ?And just for the heck of it, I pulled a similar crystal out of a SX-71 awaiting restoration and it’s doing exactly the same thing.? Still mulling that over. ? 73 – Steve, KW4H ? I've owned several SX-110's over the years, including the one I used as a Novice back in '67, that was like new I acquired from original owner. Never had any issues with xtal instability. They all were fairly stable after initial 10-15 min. warmup. Sounds like you need a new xtal.
In a message dated 11/2/2022 1:23:14 PM Eastern Standard Time, reedsteve@... writes:
Sent from Proton Mail for iOS 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 – Steve, KW4H ? ?
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Re: SX-110 Crystal Instability
This is perhaps your test? configuration Steve. I have made? jigs with the? crystal socket and a PCB ?that then plugs into?? my VNA. I would think you could make a jog with shielded? cables and rigid connectors. Just be aware that cable capacity? will likely alter the resonant frequency. ? Regards, Dale W4OP ?
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From: [email protected] [mailto:[email protected]] On Behalf Of KW4H via groups.io
Sent: Wednesday, November 2, 2022 2:49 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-110 Crystal Instability? Yeah, I ordered a couple of 455 KHz crystals today.? It would be good to have another on hand.? ? FYI, I stumble onto these things because I restore boat anchors (mostly receivers) for educational and historical purposes.? I also write articles for ER magazine, and the extra information is fun and interesting.? Anyway, I’m more likely to remove a component and test it out of curiosity rather than questioning the design.? The unstable crystal caught me by surprise! ?And just for the heck of it, I pulled a similar crystal out of a SX-71 awaiting restoration and it’s doing exactly the same thing.? Still mulling that over. ? 73 – Steve, KW4H ? I've owned several SX-110's over the years, including the one I used as a Novice back in '67, that was like new I acquired from original owner. Never had any issues with xtal instability. They all were fairly stable after initial 10-15 min. warmup. Sounds like you need a new xtal.
In a message dated 11/2/2022 1:23:14 PM Eastern Standard Time, reedsteve@... writes:
Sent from Proton Mail for iOS 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 – Steve, KW4H ? ?
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Re: SX-110 Crystal Instability
Yeah, I ordered a couple of 455 KHz crystals today.? It would be good to have another on hand.? ? FYI, I stumble onto these things because I restore boat anchors (mostly receivers) for educational and historical purposes.? I also write articles for ER magazine, and the extra information is fun and interesting.? Anyway, I’m more likely to remove a component and test it out of curiosity rather than questioning the design.? The unstable crystal caught me by surprise! ?And just for the heck of it, I pulled a similar crystal out of a SX-71 awaiting restoration and it’s doing exactly the same thing.? Still mulling that over. ? 73 – Steve, KW4H ? I've owned several SX-110's over the years, including the one I used as a Novice back in '67, that was like new I acquired from original owner. Never had any issues with xtal instability. They all were fairly stable after initial 10-15 min. warmup. Sounds like you need a new xtal.
In a message dated 11/2/2022 1:23:14 PM Eastern Standard Time, reedsteve@... writes:
Sent from Proton Mail for iOS On Wed, Nov 2, 2022 at 10:20 AM, Richard Knoppow <1oldlens1@...> wrote:
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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 – Steve, KW4H ? ?
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Re: SX-110 Crystal Instability
I've owned several SX-110's over the years, including the one I used as a Novice back in '67, that was like new I acquired from original owner. Never had any issues with xtal instability. They all were fairly stable after initial 10-15 min. warmup. Sounds like you need a new xtal.
?
GL/73,
Bob K3AC
In a message dated 11/2/2022 1:23:14 PM Eastern Standard Time, reedsteve@... writes:
?
Tried that. ?
?
Sent from Proton Mail for iOS
?
?
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 – Steve, KW4H
?
?
|
Re: SX-110 Crystal Instability
Tried that. ?
Sent from Proton Mail for iOS
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 – Steve, KW4H ? ?
|
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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Show quoted text
-------- 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 – Steve, KW4H ? ?
|
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 – 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 – 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 – 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 – 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.
|
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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Show quoted text
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 – 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 – 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 – 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.
|
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 – 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 – 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 – 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.
|
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
|
Re: SX-71 Crystal Filter Alignment Woes
Forgot to mention – 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 – 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 – 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 – 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 – 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 – 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 – 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.
|
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 – 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 – 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 – 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.
|
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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Bill (Group Owner)
Randy - W7HMT - North Bend WA
don Root