Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Hi, Emanuele,
There is a gimmick in the S-85 schematic and parts list, C38, that has a
capacitance of 2 mmfd (pF). It should, ideally, be a twisted assembly
just about 10 percent shorter than is required to emulate C62 in the
S-40B if you want to check what a gimmick of about the right size ought
to look like.
C38 couples the CW oscillator signal from the junction of pin 3 of V5
(6SC7), R29, and C55 to pin 4 of V4 (6SK7).
The S-40B also uses C38, specified in the S-40B parts list as 2 mmf but
labeled on the schematic with "1," implying 1 pF.
Incidentally, Note 2 in the S-85 schematic states that all capacitor
values are in "MMF" unless otherwise specified. In the parts list, C38
and others are specified in "mmfd." The S-40B parts list uses "mmf" and
"mfd."
73,
Maynard
W6PAP
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On 2/15/25 08:14, Maynard Wright wrote: Hi, Richard,
Yes, that's exactly as it is in the S-40B, in the schematic and in the
receiver.? It's C62, a 2.2 pF cap (2.2 mmf in the S-40B parts list).
But the S-85 lacks that cap, in the S-85 schematic, the S-85 parts list,
and in Emanuele's S-85.
So Emanuele added a twisted wire gimmick capacitor to his S-85 where C62
is in the S-40B and saw a significant rise in signal levels on Bands 1
and 2.
My thought is that by adjusting the capacitance of his gimmick, or by
replacing it with a 2.2 pf capacitor, he might make it possible to
achieve a correct alignment of Bands 1 and 2 of his S-85.
I think that it's unfortunate that the Hallicrafters schematic of the
S-40B labels C62 as just "2.2."? My first thought was 2.2 uF, but the
S-40B parts list shows 2.2 mmf.
73,
Maynard
W6PAP
On 2/14/25 20:30, Richard Knoppow via groups.io wrote:
Very interesting Maynard. I am not sure I am seeing this straight
but it appears that there is an RC load on the RF tube coupled via the
2.2 uF cap to the tuned circuit of the mixer grid. Should result in a
fairly low gain and fairly broad tuning. That might be desirable for the
broadcast band I am still not sure how the antenna coupling works for a
balanced input.
On 2/14/2025 6:45 PM, Maynard Wright via groups.io wrote:
??? Hi, Richard,
??? You are right about the two small caps. But trace carefully what S1B
??? (front) is doing when set to Band 1. The RF signal is passed from the
??? plate of V1 through R4 and down to R26/C29. It cannot appear below
that
??? RC combination because the B+ line should be at ground for RF. So
??? without C62, there is no path for RF forward from V1, at least in the
??? schematic.
??? So I wonder whether Emanuele might achieve good results across the
full
??? ranges of Bands 1 and 2 by adjusting the amount of capacitance his
??? gimmick provides or by using a 2.2 pF cap as in the S-40B.
??? 73,
??? Maynard
??? W6PAP
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Hi, Richard,
Yes, that's exactly as it is in the S-40B, in the schematic and in the
receiver. It's C62, a 2.2 pF cap (2.2 mmf in the S-40B parts list).
But the S-85 lacks that cap, in the S-85 schematic, the S-85 parts list,
and in Emanuele's S-85.
So Emanuele added a twisted wire gimmick capacitor to his S-85 where C62
is in the S-40B and saw a significant rise in signal levels on Bands 1
and 2.
My thought is that by adjusting the capacitance of his gimmick, or by
replacing it with a 2.2 pf capacitor, he might make it possible to
achieve a correct alignment of Bands 1 and 2 of his S-85.
I think that it's unfortunate that the Hallicrafters schematic of the
S-40B labels C62 as just "2.2." My first thought was 2.2 uF, but the
S-40B parts list shows 2.2 mmf.
73,
Maynard
W6PAP
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On 2/14/25 20:30, Richard Knoppow via groups.io wrote: Very interesting Maynard. I am not sure I am seeing this straight
but it appears that there is an RC load on the RF tube coupled via the
2.2 uF cap to the tuned circuit of the mixer grid. Should result in a
fairly low gain and fairly broad tuning. That might be desirable for the
broadcast band I am still not sure how the antenna coupling works for a
balanced input.
On 2/14/2025 6:45 PM, Maynard Wright via groups.io wrote:
Hi, Richard,
You are right about the two small caps. But trace carefully what S1B
(front) is doing when set to Band 1. The RF signal is passed from the
plate of V1 through R4 and down to R26/C29. It cannot appear below that
RC combination because the B+ line should be at ground for RF. So
without C62, there is no path for RF forward from V1, at least in the
schematic.
So I wonder whether Emanuele might achieve good results across the full
ranges of Bands 1 and 2 by adjusting the amount of capacitance his
gimmick provides or by using a 2.2 pF cap as in the S-40B.
73,
Maynard
W6PAP
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Very interesting Maynard. I am not sure I am seeing this straight
but it appears that there is an RC load on the RF tube coupled via the
2.2 uF cap to the tuned circuit of the mixer grid. Should result in a
fairly low gain and fairly broad tuning. That might be desirable for the
broadcast band I am still not sure how the antenna coupling works for a
balanced input.
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On 2/14/2025 6:45 PM, Maynard Wright via groups.io wrote: Hi, Richard,
You are right about the two small caps. But trace carefully what S1B
(front) is doing when set to Band 1. The RF signal is passed from the
plate of V1 through R4 and down to R26/C29. It cannot appear below that
RC combination because the B+ line should be at ground for RF. So
without C62, there is no path for RF forward from V1, at least in the
schematic.
So I wonder whether Emanuele might achieve good results across the full
ranges of Bands 1 and 2 by adjusting the amount of capacitance his
gimmick provides or by using a 2.2 pF cap as in the S-40B.
73,
Maynard
W6PAP
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Hi, Richard,
You are right about the two small caps. But trace carefully what S1B
(front) is doing when set to Band 1. The RF signal is passed from the
plate of V1 through R4 and down to R26/C29. It cannot appear below that
RC combination because the B+ line should be at ground for RF. So
without C62, there is no path for RF forward from V1, at least in the
schematic.
So I wonder whether Emanuele might achieve good results across the full
ranges of Bands 1 and 2 by adjusting the amount of capacitance his
gimmick provides or by using a 2.2 pF cap as in the S-40B.
73,
Maynard
W6PAP
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On 2/14/25 15:55, Richard Knoppow via groups.io wrote: C-62 in the S-40B is a small cap from the plate of the RF amp to
the grid of the converter. In the S-85 there are two such caps, one on
each of the low band tuned circuits. All listed as Bakelite caps. I have
seen illustrations of Bakelite caps somewhere, essentially a very low
value cap made by embedding two wires in a pit of Bakelite. Probably
more accurate and stable than a gimmick. I am no longer certain I can
analyze this circuit but it appears that these small value caps are to
equalize the gain of the RF stage.
I wonder if there was ever a Sam's or Rider's handbook for the S-85
or the S-40B for that matter. Both seem to have redrawn factory
schematics and are often somewhat clearer. I looked but could not find any.
I looked at the photo of the bottom of the S-40B in the handbook
but its not really that clear. My idea was to see of the L-3 coil, which
is for both low bands, was situated such that it could be coupled by
mutual inductance to the other coils.
I also looked at the Radiotron Designer's Handbook to see if there
was anything in it about RF amplifiers. There is but it wasn't helpful.
I have some other material on broadcast receiver design and will keep
looking.
Its too bad that someone with a _working_ S-85 can't look at it and
seen what it actually there. Very frustrating.
On 2/14/2025 3:07 PM, Emanuele Girlando via groups.io wrote:
D
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Jim, it seems like switching makes the big difference. Presumably there are 3 longer wires running a distance to the switch. Might one of them be getting to close to the B+ wires, or something like that. Although It hardly matters, the switch is for base ¡°boost¡± I think, but the boost seems to be bypassed while in the ¡®IN¡± position, and in use while in the ¡°out position¡±.. confusing to me so far. ?? -- don??? va3drl
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Emanuele, the record is quite a bit higher yet ..maybe 140 ! I¡¯ll blame Nick for STARTING ?the deviation into the mixer tanks circuits and then letting us squabble about the no C62. My guess is that it is not related to your original problem. ? With more reassurance about the main dial setting, my list of common mode ¡°failures¡± has run dry for now. I¡¯m just talking too loudly now, and as a reminder it seems that 4 trimmers have too much minimum capacitance when aligning. It is possible that they all ¡°failed¡± in the same way, or that they were wrong in the factory, ¡BUT¡ a very long shot L3 and L6 could be too high? ?¡BUT¡ ?a very long shot There could be a hidden capacitance ??¡BUT¡ in the RF and mixer both? ??¡ a very long shot What is left? ? Before pulling things apart¡ Some ?thoughts, written poorly, but maybe you can get the jist. ?Why not scan the? tanks at the low ends ?[ .6 MC and 1.8 MC] to see where they resonate, and see if adjusting the trimmers helps or hinders so you will know if it peaks somewhat low all over the band, or if it peaks too high at the bottom. This might reveal something. ? With main and BS at the top, those trimmers would theoretically shift the frequency by a factor of about 3, but of course it won¡¯t be that since there is ?a bit of pF? in the main and BS [they don¡¯t tell us], but if the range is reasonable they would appear to be working reasonably. ? ? The trimmers can¡¯t do much to the peaking at [ .6 MC and 1.8 MC] on the dial, so if the? peakings are off by much down there, something is really amuck, not just the trimmers. ?Are they all acting in a similar way down there. At some point it might be worth thinking about ?why the coils might not be as we think they should be.. grounding wipers on switches? ?? I saw nothing about the history of this specific unit.? Did it seem original?, some typical repairs?, all upgraded by somebody?, never used. Some resistors look original. ? Still strange.. works well on high bands, but common symptom on both low bands. Wiring on top of my neck is fried!
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From: [email protected] [mailto:[email protected]] On Behalf Of Emanuele Girlando via groups.io
Sent: Friday, February 14, 2025 6:17 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!? A sad message to celebrate the 100th message of the thread: I'm starting to fear having to disassemble the ANT and MIX circuits from the chassis: something I would have gladly avoided doing... but I think it's the only way to test the components one by one. -- don??? va3drl
|
Re: Hallicrafters Radios for Sale
Hi Don,
?
? ? Not sure if there is more than one model.? ? Come on down to the flea and take a look.
?
The one we have is working and in nice shape.??
?
Regards,
?
? ? ?Gene
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
C-62 in the S-40B is a small cap from the plate of the RF amp to
the grid of the converter. In the S-85 there are two such caps, one on
each of the low band tuned circuits. All listed as Bakelite caps. I have
seen illustrations of Bakelite caps somewhere, essentially a very low
value cap made by embedding two wires in a pit of Bakelite. Probably
more accurate and stable than a gimmick. I am no longer certain I can
analyze this circuit but it appears that these small value caps are to
equalize the gain of the RF stage.
I wonder if there was ever a Sam's or Rider's handbook for the S-85
or the S-40B for that matter. Both seem to have redrawn factory
schematics and are often somewhat clearer. I looked but could not find any.
I looked at the photo of the bottom of the S-40B in the handbook
but its not really that clear. My idea was to see of the L-3 coil, which
is for both low bands, was situated such that it could be coupled by
mutual inductance to the other coils.
I also looked at the Radiotron Designer's Handbook to see if there
was anything in it about RF amplifiers. There is but it wasn't helpful.
I have some other material on broadcast receiver design and will keep
looking.
Its too bad that someone with a _working_ S-85 can't look at it and
seen what it actually there. Very frustrating.
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On 2/14/2025 3:07 PM, Emanuele Girlando via groups.io wrote: D
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
I wonder whether too much coupling (or not enough) might affect the
ability to align the stage. I think that you are on the right track.
100 messages? Wow! I can't recall now whether you made the change we
were originally thinking about in the RF input circuitry (at age 82 I
think I'm blessed to remember my name). If so, is it back to the way
the schematic shows now?
73,
Maynard
W6PAP
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On 2/14/25 15:07, Emanuele Girlando via groups.io wrote: Don,
the dials were (and are) installed as per Service instructions. My
sig-gen tests were done to confirm this and to align the OSC tanks.
*GUYS, I HAVE INSTALLED C62 in my S-85.*
It is a gimmick arrangement: two wires twisted together for length of
about 5 cm (a little less then a couple of inches, if I convert metric
to imperial correctly).
Results:
1. about 20dB increase in sensitivity in bands 1&2. A -70/-80dBm signal
was barely audible without C62, now I can clearly hear it at -100dBm
- GREAT!
Unfortunately this apply to higher halves of the bands only. In
lower halves the signal disappears (as before) even if forced to
-20dBm or more.
2. nothing changed in the MIX alignment and, obviously, in the ANT as
well: TRIMCAPs don't peak.
--
Emanuele (IU1KNR).
<>
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
A sad message to celebrate the 100th message of the thread: I'm starting to fear having to disassemble the ANT and MIX circuits from the chassis: something I would have gladly avoided doing... but I think it's the only way to test the components one by one.
--
Emanuele (IU1KNR).
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Don,
the dials were (and are) installed as per Service instructions. My sig-gen tests were done to confirm this and to align the OSC tanks.
?
GUYS, I HAVE INSTALLED C62 in my S-85.
It is a gimmick arrangement: two wires twisted together for length of about 5 cm (a little less then a couple of inches, if I convert metric to imperial correctly).
Results:
- about 20dB increase in sensitivity in bands 1&2. A -70/-80dBm signal was barely audible without C62, now I can clearly hear it at -100dBm - GREAT!
Unfortunately this apply to higher halves of the bands only. In lower halves the signal disappears (as before) even if forced to -20dBm or more.
- nothing changed in the MIX alignment and, obviously, in the ANT as well: TRIMCAPs don't peak.
--
Emanuele (IU1KNR).
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Hi jim, ?RE? C4 and C15 both peak nicely (by ear) at 1.4 MHz ???always good to have a verification? ? ? After looking at the S40B, we might just have to resort to the gimmick idea, but with the capacitance being between the front and rear of S1B Possibly enough capacitance? PS I tried to make this so most others could understand my thought. ?
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From: [email protected] [mailto:[email protected]] On Behalf Of JThorusen
Sent: Friday, February 14, 2025 4:48 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!? I have been following this thread for awhile and I thought I'd add what data I can.?? I have my S-85 apart on the dining room table and I can state the following using my VNA as a signal source: 1.?? The RF amp (6SG7) is definitely in the circuit.?? When this tube is pulled, the signal goes away. 2.?? C4 and C15 both peak nicely (by ear) at 1.4 MHz. Unfortunately, the area around S1B is very crowded and visibility is poor.?? As far as I can tell, the unit is wired just as the schematic states; I'm sure there is a divergence somewhere as the circuit cannot function as drawn, but I cannot find the difference. This is probably not much help, but it is the best I can do at this time. -- don??? va3drl
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Greetings to the Group:
?
I have been following this thread for awhile and I thought I'd add what data I can.?? I have my S-85 apart on the dining room table and I can state the following using my VNA as a signal source:
?
1.?? The RF amp (6SG7) is definitely in the circuit.?? When this tube is pulled, the signal goes away.
2.?? C4 and C15 both peak nicely (by ear) at 1.4 MHz.
?
Unfortunately, the area around S1B is very crowded and visibility is poor.?? As far as I can tell, the unit is wired just as the schematic states; I'm sure there is a divergence somewhere as the circuit cannot function as drawn, but I cannot find the difference.
?
This is probably not much help, but it is the best I can do at this time.
?
73,
--
Jim T.
KB6GM
|
Thanks Jim, will look into those areas.
Tom
Look at the audio response curve in the manual.? With the BASS switch IN, the low frequency audio is emphasized, not attenuated.??
The BASS switch in the IN position shorts out two components, CH2 and C43, I would look there first.? Perhaps there is AC being coupled into the audio circuit via CH2?? Check that the mounting screws for CH2 are making good contact with the chassis,? Corrosion between the screw head and chassis could be the problem so loosen and then tighten them.? Might as well do the same for any screw that supplies a ground or chassis connection for the audio circuit in that area of the chassis. Regards, Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
Good idea, but I pulled V12, 6SC7, and the hum remains. It is definitely in the output stages Tom
Tom Good for you Presumably, the base ¡°In¡± position filters out the hum as expected¡ And the hum comes from upstream, maybe the AF gain? Pot area or a bad contact in the phones switch, or even before that. ?? ?
From: [email protected] [mailto:[email protected]] On Behalf Of thoyer via groups.io
Sent: Thursday, February 13, 2025 7:22 PM
To: [email protected]
Subject: [HallicraftersRadios] SX-28A Hum ? I just finished pretty much a complete overhaul of a nice condition (physically) SX-28A. Replaced just about every resistor and all caps. ? Radio is working well except for a 120hz hum. When I switch the Bass in, the hum goes away. ? Yes, there is ripple on the plates of the 6V6¡¯s, about 6vrms, but that is there independent of the bass switch position. The output side of the HV filter is clean, no ripple. I paralleled another 47uf 450v cap across the choke input cap and there was no difference. ? I double checked the wiring against the schematic along with component values. Is the schematic correct in this area? I found once schematic error maybe there is another? ? Thoughts? ? Tom W3TA
--
don??? va3drl
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Emanuele, ??Oh, I should not have jumped to conclusions on a gimmick, but just maybe the band switch itself acts as a gimmick. Re the main dial, I meant this 
?
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From: [email protected] [mailto:[email protected]] On Behalf Of Emanuele Girlando via groups.io
Sent: Friday, February 14, 2025 4:23 AM
To: [email protected]
Subject: Re: [HallicraftersRadios] S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!? I didn't see any gimmick arrangement in my S-85. I can confirm once again C62 is not installed in my S-85 neither as a discrete component nor a a gimmick arrangement. the main tuning dial seems perfectly positioned to me. When I inject a signal from my sig-gen into the receiver, I find it exactly where I expect it to be. -- don??? va3drl
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
It would be interesting to have someone who has a perfectly working S-85
that aligns correctly on all bands to check for the presence of C62 or
an equivalent coupling arrangement.
Of course, most folks who have such an S-85 probably have the case in
place and it's maybe too much to ask them to pull the case to check this
out.
73,
Maynard
W6PAP
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On 2/14/25 01:22, Emanuele Girlando via groups.io wrote: Don,
I didn't see any gimmick arrangement in my S-85.
I can confirm once again C62 is not installed in my S-85 neither as a
discrete component nor a a gimmick arrangement.
the main tuning dial seems perfectly positioned to me. When I inject a
signal from my sig-gen into the receiver, I find it exactly where I
expect it to be.
--
Emanuele (IU1KNR).
<>
|
Look at the audio response curve in the manual.? With the BASS switch IN, the low frequency audio is emphasized, not attenuated.??
The BASS switch in the IN position shorts out two components, CH2 and C43, I would look there first.? Perhaps there is AC being coupled into the audio circuit via CH2?? Check that the mounting screws for CH2 are making good contact with the chassis,? Corrosion between the screw head and chassis could be the problem so loosen and then tighten them.? Might as well do the same for any screw that supplies a ground or chassis connection for the audio circuit in that area of the chassis. Regards, Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
Good idea, but I pulled V12, 6SC7, and the hum remains. It is definitely in the output stages Tom
Tom Good for you Presumably, the base ¡°In¡± position filters out the hum as expected¡ And the hum comes from upstream, maybe the AF gain? Pot area or a bad contact in the phones switch, or even before that. ?? ?
From: [email protected] [mailto:[email protected]] On Behalf Of thoyer via groups.io
Sent: Thursday, February 13, 2025 7:22 PM
To: [email protected]
Subject: [HallicraftersRadios] SX-28A Hum ? I just finished pretty much a complete overhaul of a nice condition (physically) SX-28A. Replaced just about every resistor and all caps. ? Radio is working well except for a 120hz hum. When I switch the Bass in, the hum goes away. ? Yes, there is ripple on the plates of the 6V6¡¯s, about 6vrms, but that is there independent of the bass switch position. The output side of the HV filter is clean, no ripple. I paralleled another 47uf 450v cap across the choke input cap and there was no difference. ? I double checked the wiring against the schematic along with component values. Is the schematic correct in this area? I found once schematic error maybe there is another? ? Thoughts? ? Tom W3TA
--
don??? va3drl
|
Interesting, I'll look into this.
Thanks,? Tom
Check whether the windings of the audio output transformer are really symmetrical. This is how the two anodes of the 6v6 are fed and the remaining hum in the end circuit is eliminated. The hum is eliminated by the two (opposing) windings. ? ? I just finished pretty much a complete overhaul of a nice condition (physically) SX-28A. Replaced just about every resistor and all caps. ? Radio is working well except for a 120hz hum. When I switch the Bass in, the hum goes away. ? Yes, there is ripple on the plates of the 6V6¡¯s, about 6vrms, but that is there independent of the bass switch position. The output side of the HV filter is clean, no ripple. I paralleled another 47uf 450v cap across the choke input cap and there was no difference. ? I double checked the wiring against the schematic along with component values. Is the schematic correct in this area? I found once schematic error maybe there is another? ? Thoughts? ? Tom W3TA
|
Good idea, but I pulled V12, 6SC7, and the hum remains. It is definitely in the output stages Tom
Tom Good for you Presumably, the base ¡°In¡± position filters out the hum as expected¡ And the hum comes from upstream, maybe the AF gain? Pot area or a bad contact in the phones switch, or even before that. ?? ?
From: [email protected] [mailto:[email protected]] On Behalf Of thoyer via groups.io
Sent: Thursday, February 13, 2025 7:22 PM
To: [email protected]
Subject: [HallicraftersRadios] SX-28A Hum ? I just finished pretty much a complete overhaul of a nice condition (physically) SX-28A. Replaced just about every resistor and all caps. ? Radio is working well except for a 120hz hum. When I switch the Bass in, the hum goes away. ? Yes, there is ripple on the plates of the 6V6¡¯s, about 6vrms, but that is there independent of the bass switch position. The output side of the HV filter is clean, no ripple. I paralleled another 47uf 450v cap across the choke input cap and there was no difference. ? I double checked the wiring against the schematic along with component values. Is the schematic correct in this area? I found once schematic error maybe there is another? ? Thoughts? ? Tom W3TA
--
don??? va3drl
|
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Don,
I didn't see any gimmick arrangement in my S-85.
I can confirm once again C62 is not installed in my S-85 neither as a discrete component nor a a gimmick arrangement.
the main tuning dial seems perfectly positioned to me. When I inject a signal from my sig-gen into the receiver, I find it exactly where I expect it to be.
--
Emanuele (IU1KNR).
|
don Root
Emanuele Girlando
Jim Whartenby