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Came home and fired the rig up. let it run for an hour. Found a 10 to 15 W carrier on Both side bands.
Attempted to NULL the carrier.? The POT works and did null it down to 3W.?
The Trimmer Cap only has an effect of maybe .5w.? ?
I clipped a counter to the test point of the carrier xtals and could not believe it. Both xtals had moved in the right direction!? ?
What the heck.? They are both spot on now.? 1648.550. I can adjust up and down from there. That xtal was best case 1648.4?
I guess the trimmer failed???? ?
I hate to have to change it. its riveted in.? I have a replacement 5 to 25PF trimmer.? Also new modern diodes. I guess I will rebuild this circuit now.
C
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Hey,
Take pics of the trimmer upgrade.
Thanks, dave wa3gin
On Mon, Apr 1, 2024 at 9:21?PM W7WRX < clark@...> wrote: Came home and fired the rig up. let it run for an hour. Found a 10 to 15 W carrier on Both side bands.
Attempted to NULL the carrier.? The POT works and did null it down to 3W.?
The Trimmer Cap only has an effect of maybe .5w.? ?
I clipped a counter to the test point of the carrier xtals and could not believe it. Both xtals had moved in the right direction!? ?
What the heck.? They are both spot on now.? 1648.550. I can adjust up and down from there. That xtal was best case 1648.4?
I guess the trimmer failed???? ?
I hate to have to change it. its riveted in.? I have a replacement 5 to 25PF trimmer.? Also new modern diodes. I guess I will rebuild this circuit now.
C
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Hello C, I don’t know anything about the rig, but with that cap riveted in, if you think that cap is shot but not certain, perhaps? jump it somehow with a good cap of some reasonable value, and see what happens.. just an idea , but I don’t understand the circuit. ?,, ahhh maybe a bad riveted connection… HooNose ?
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From: [email protected] [mailto:[email protected]] On Behalf Of W7WRX
Sent: Monday, April 1, 2024 9:21 PM
To: [email protected]
Subject: [HallicraftersRadios] SR2000 Cant Null carrier? Came home and fired the rig up. let it run for an hour. Found a 10 to 15 W carrier on Both side bands.
Attempted to NULL the carrier.? The POT works and did null it down to 3W.?
The Trimmer Cap only has an effect of maybe .5w.? ?
I clipped a counter to the test point of the carrier xtals and could not believe it. Both xtals had moved in the right direction!? ?
What the heck.? They are both spot on now.? 1648.550. I can adjust up and down from there. That xtal was best case 1648.4?
I guess the trimmer failed???? ?
I hate to have to change it. its riveted in.? I have a replacement 5 to 25PF trimmer.? Also new modern diodes. I guess I will rebuild this circuit now.
C ? -- don??? va3drl
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Ok.? I need to measure the one I have to make sure it will be a direct fit.? Nervous about drilling the rivets.? Don't have much of a choice I guess.
C
Hey,
Take pics of the trimmer upgrade.
Thanks,
dave
wa3gin
On Mon, Apr 1, 2024 at 9:21?PM W7WRX < clark@...> wrote:
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Came home and fired the rig up. let it run for an hour. Found a 10 to 15 W carrier on Both side bands.
Attempted to NULL the carrier.? The POT works and did null it down to 3W.?
The Trimmer Cap only has an effect of maybe .5w.? ?
I clipped a counter to the test point of the carrier xtals and could not believe it. Both xtals had moved in the right direction!? ?
What the heck.? They are both spot on now.? 1648.550. I can adjust up and down from there. That xtal was best case 1648.4?
I guess the trimmer failed???? ?
I hate to have to change it. its riveted in.? I have a replacement 5 to 25PF trimmer.? Also new modern diodes. I guess I will rebuild this circuit now.
C
|
Certainly,? you might not want to use a drill.? Instead use a dremel?tool and have a running shop vac?hose next to the dremel to suck up all of the metal filings.
Good Luck, dave wa3gin
On Mon, Apr 1, 2024 at 11:11?PM W7WRX < clark@...> wrote:
Ok.? I need to measure the one I have to make sure it will be a direct fit.? Nervous about drilling the rivets.? Don't have much of a choice I guess.
C
Hey,
Take pics of the trimmer upgrade.
Thanks,
dave
wa3gin
On Mon, Apr 1, 2024 at 9:21?PM W7WRX < clark@...> wrote:
Came home and fired the rig up. let it run for an hour. Found a 10 to 15 W carrier on Both side bands.
Attempted to NULL the carrier.? The POT works and did null it down to 3W.?
The Trimmer Cap only has an effect of maybe .5w.? ?
I clipped a counter to the test point of the carrier xtals and could not believe it. Both xtals had moved in the right direction!? ?
What the heck.? They are both spot on now.? 1648.550. I can adjust up and down from there. That xtal was best case 1648.4?
I guess the trimmer failed???? ?
I hate to have to change it. its riveted in.? I have a replacement 5 to 25PF trimmer.? Also new modern diodes. I guess I will rebuild this circuit now.
C
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The mount is insulated so rivets dont ground the cap..?
The cap is not adjusting the circuit.? They are known to fail.??
I put a drop of dexoit on it last night as a last resort. It did not fix it this morning.?
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Hi Dave,
I'm fairly certain the capacitor is not the problem.? The rivets holding the function switch have loosened or oxidized from switching.? There is one black wire to ground that was to protect for this but is inadequate.? Drill one or both rivets out and wipe a film of copper butter between the bracket plate and chassis and secure with a screw.? Voila the radio will become stable.
When restoring radios that use an aluminum chassis and riveted components, the following procedure will fix 95% of the strange behaviors.? Dab a bit of Deoxit 100 on each star washer between the chassis and socket or wherever you find one and using a screwdriver, tap the star washer to reset the teeth.? For ALL screws, remove and dab a bit or copper butter and replace.? A PITA but that is a complex radio, and any ground loops will test your patience and satisfaction.?
Kindest regards Jim K9AXN? ? ??
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Thanks Jim. I will check that.? I fail to see how this could make a trimmer cap not work.? There is a carrier on both side bands of about 2w.? I can kick the Carrier osc around and null the carrier which tells me that the Null circuit is not adjusting.
But I will start with the function switch and use the deoxit on the screws first!
C
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Hi Dave,
I'm fairly certain the capacitor is not the problem.? The rivets holding the function switch have loosened or oxidized from switching.? There is one black wire to ground that was to protect for this but is inadequate.? Drill one or both rivets out and wipe
a film of copper butter between the bracket plate and chassis and secure with a screw.? Voila the radio will become stable.
When restoring radios that use an aluminum chassis and riveted components, the following procedure will fix 95% of the strange behaviors.? Dab a bit of Deoxit 100 on each star washer between the chassis and socket or wherever you find one and using a screwdriver,
tap the star washer to reset the teeth.? For ALL screws, remove and dab a bit or copper butter and replace.? A PITA but that is a complex radio, and any ground loops will test your patience and satisfaction.?
Kindest regards Jim K9AXN? ? ??
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I cleaned and tightened everything including the bracket. No change.?
I drilled the rivets and removed the old Trimmer. It was bad. It reads nothing on my LCR.?
New trimmer reads 4 to 26 pf.? Rated at 25pf.
I had to space it from the chassis. It is different.??
plugged back in. NO change.? I can adjust the trimmer and null .5w either way.? The pot and trimmer manipulation ends at 2w output.? That is for BOTH side bands LSB and USB
GRRRRR...? I am going to look for the exact trimmer now. If anyone has one please let me know!!!
I guess I am going to have to replace the diodes, resistors and the .005. Just gut it all and start over.? This is crazy. The rig was DONE and one the air working.
C
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This may be irrelevant to the SR-2000, I am not familiar with it. I
had a similar problem with a Drake T4XB, couldn't null the carrier. I
found, after considerable waste motion, the problem was wiring. A
previous owner had re-wired part of the balanced modulator. While the
wiring _looked_ perfectly fine, it was not. I got photographs of the
correct wiring from Garry Barrell (SK) who was the maven of Drake. Turns
out the the wires to the diode bridge were reversed. It was not the
polarity but the location of the wires that made the difference. The
stray capacitance was so different it put the trimming cap out of range.
I restored the original wiring and the null was perfect and right in the
center of the trimmer range.
Is it possible that something in this rig has changed? You might
need pix of the correct wiring to compare to yours.
Again, may be irrelevant to your problem but on my transmitter it
caused me to chase my tail for quite a while.
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On 4/2/2024 4:06 PM, W7WRX wrote: I cleaned and tightened everything including the bracket. No change.
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Thank you for the suggestion.? The radio was working and done.? It then just the next day all the sudden had the carrier.? The trimmer was in fact bad and according to Walt's guide, this is common.
I have had this problem several times now on various rigs.? The Invader 2000 had this issue and only after I shot gunned the ENTIRE circuit, Resistors, trimmers, Diodes and caps, Did it start working again. The resistors did go way up in value.
Also had this problem with my Collins S line. The 32S3C had 1 watt of carrier.? I replaced the odd diode bridge with 4 1n5711s and I added a small ceramic cap and bingo it nulled.?
I found the exact model NPO trimmers on Ebay. I ordered 5.? Its going to be a week down time. They are in New Hampshire. Just about as far as you could possibly get from my QTH.
When they get here, I will get some new small hardware and install the trimmer. It will look like factory.? I will replace ALL of it.? Every part so it is all NEW.? ?Then, Cross my fingers and key it up.??
These things have not been on and used in maybe 40 years. They have put up a hell of a fight.? But they will both be expertly repaired and work better than new when I am complete. It's just going to take more time.
C
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Clark,
Any chance this unwanted carrier is an audio chain issue??
73 wa3gin
On Tue, Apr 2, 2024 at 7:33?PM W7WRX < clark@...> wrote: Thank you for the suggestion.? The radio was working and done.? It then just the next day all the sudden had the carrier.? The trimmer was in fact bad and according to Walt's guide, this is common.
I have had this problem several times now on various rigs.? The Invader 2000 had this issue and only after I shot gunned the ENTIRE circuit, Resistors, trimmers, Diodes and caps, Did it start working again. The resistors did go way up in value.
Also had this problem with my Collins S line. The 32S3C had 1 watt of carrier.? I replaced the odd diode bridge with 4 1n5711s and I added a small ceramic cap and bingo it nulled.?
I found the exact model NPO trimmers on Ebay. I ordered 5.? Its going to be a week down time. They are in New Hampshire. Just about as far as you could possibly get from my QTH.
When they get here, I will get some new small hardware and install the trimmer. It will look like factory.? I will replace ALL of it.? Every part so it is all NEW.? ?Then, Cross my fingers and key it up.??
These things have not been on and used in maybe 40 years. They have put up a hell of a fight.? But they will both be expertly repaired and work better than new when I am complete. It's just going to take more time.
C
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No sir. I pulled the mic amp tube.? Its the carrier leaking through.? I can adjust it from 2w to 200w.
C
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Clark,
Any chance this unwanted carrier is an audio chain issue??
73
wa3gin
On Tue, Apr 2, 2024 at 7:33?PM W7WRX < clark@...> wrote:
Thank you for the suggestion.? The radio was working and done.? It then just the next day all the sudden had the carrier.? The trimmer was in fact bad and according to Walt's guide, this is common.
I have had this problem several times now on various rigs.? The Invader 2000 had this issue and only after I shot gunned the ENTIRE circuit, Resistors, trimmers, Diodes and caps, Did it start working again. The resistors did go way up in value.
Also had this problem with my Collins S line. The 32S3C had 1 watt of carrier.? I replaced the odd diode bridge with 4 1n5711s and I added a small ceramic cap and bingo it nulled.?
I found the exact model NPO trimmers on Ebay. I ordered 5.? Its going to be a week down time. They are in New Hampshire. Just about as far as you could possibly get from my QTH.
When they get here, I will get some new small hardware and install the trimmer. It will look like factory.? I will replace ALL of it.? Every part so it is all NEW.? ?Then, Cross my fingers and key it up.??
These things have not been on and used in maybe 40 years. They have put up a hell of a fight.? But they will both be expertly repaired and work better than new when I am complete. It's just going to take more time.
C
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C, ?here I am intruding again. Re ??“It reads nothing on my LCR.?“?? ??so is it shorted?? Or really really wide open? or “other”??? Seems strange from here. What could have happened to it? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of W7WRX
Sent: Tuesday, April 2, 2024 7:07 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SR2000 Cant Null carrier? I cleaned and tightened everything including the bracket. No change.?
I drilled the rivets and removed the old Trimmer. It was bad. It reads nothing on my LCR.?
New trimmer reads 4 to 26 pf.? Rated at 25pf.
I had to space it from the chassis. It is different.??
plugged back in. NO change.? I can adjust the trimmer and null .5w either way.? The pot and trimmer manipulation ends at 2w output.? That is for BOTH side bands LSB and USB
GRRRRR...? I am going to look for the exact trimmer now. If anyone has one please let me know!!!
I guess I am going to have to replace the diodes, resistors and the .005. Just gut it all and start over.? This is crazy. The rig was DONE and one the air working.
C -- don??? va3drl
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Hi Jim
What is copper butter and can you recommend any dealer who sells it?
Thanks
sam - WS4AM
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Don. The cap was open.? I understand these are known to just up and fail.? Its listed-on Walt's document.? ?I am unsure why they fail. Just age?? Maybe corrosion?? I opened it up and it appears to be corroded.?
C
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There are two main causes for the ceramic variables failures. Long time storage in humid conditions and improper chassis cleaning methods.
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Don. The cap was open.? I understand these are known to just up and fail.? Its listed-on Walt's document.? ?I am unsure why they fail. Just age?? Maybe corrosion?? I opened it up and it appears to be corroded.?
C
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Just an observation from my experience with Collins S/Line gear.? It seems that over time, the ceramic trimmers seize and fail to turn without exerting a high twisting force.? With enough twisting pressure, the rotor quickly snaps free.? Possibly that breaking action causes the cap failure?? If the cap seems free to turn now, possibly it seized, broke free, and failed under prior ownership.? ?? ? Paul, W9AC ?
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From: [email protected] <[email protected]> On Behalf Of W7WRX
Sent: Wednesday, April 3, 2024 12:08 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SR2000 Cant Null carrier? Don. The cap was open.? I understand these are known to just up and fail.? Its listed-on Walt's document.? ?I am unsure why they fail. Just age?? Maybe corrosion?? I opened it up and it appears to be corroded.?
C
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OK C, ?I guess I am beating a dead horse, but: I am one of those guys that just gotta know exactly why something fails, along with the failure mechanism[s]. In some of my working days you couldn’t just throw out a 2000Amp bus-bars because current didn’t go from one end to the other; you had to find the problem [the real problem]! You triggered my 1950’s curiosity. I thought I knew what a trimmer is/was, but I never built one, so I guess I have been missing something. I have not been able to find details of trimmer construction; only simplified sketches. So we can only presume that ?if one plate of the capacitance part of the unit is one ?metal piece and it has fractured [maybe due to adjustment]? or [ more likely] if one plate of the capacitance part of the unit ?is SOMEHOW connected to the terminal ??metal ?using a simple compression means and that compression has weakened [maybe due to normal thermal cycling] or, as likely you are saying, corrosion wiggled it way right between the pressure/ contact points, which is all aided by the local climate conditions, and that corrosion is non-conductive [consistent with aluminum oxides] Re: “I opened it up and it appears to be corroded.”? ???Is that a one way operation, or can it be reversed? visible corrosion should not hurt, but if there is a joint …..? ? Maxwell did not allow for bad joints in his formulas.
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From: [email protected] [mailto:[email protected]] On Behalf Of W7WRX
Sent: Wednesday, April 3, 2024 12:08 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SR2000 Cant Null carrier? Don. The cap was open.? I understand these are known to just up and fail.? Its listed-on Walt's document.? ?I am unsure why they fail. Just age?? Maybe corrosion?? I opened it up and it appears to be corroded.?
C ? -- don??? va3drl
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Dave Jordan
don Root
waltcates
Paul Christensen