SX-62B alignment instructions
开云体育Hi Scott.? That’s good info. So the problem seems to be in the FM limiter /discriminator area ??I will do some head scratching, but others might have the answer first. We had a day or two of nice weather, and I was out cleaning up flower beds so now I cant move. ?
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-- don??? va3drl |
开云体育Scott, here is where I got to after slowly recalling some of the SX-42 ccts. Is this AM/FM split? the way you and anyone sees it?? this stuff is tough to digest. From the SX-62B on BAMA……. From: [email protected] [mailto:[email protected]] On Behalf Of Scott Petersen via groups.io
Sent: Monday, March 17, 2025 1:41 PM To: [email protected] Subject: Re: [HallicraftersRadios] SX-62B alignment instructions ? I have not recapped inside the Discriminator, or the IF's yet, maybe I have to do that, hoping I didn't need to, this unit seems to be the latest version, as the caps are the plastic molded ones(replaced), unlike the SX-42, which were paper/ wax. The band switch looks like a later style also, as the shaft comes apart. ? From:[email protected] <[email protected]> on behalf of don Root <drootofallevil@...> ? Hi Scott.? That’s good info. So the problem seems to be in the FM limiter /discriminator area ??I will do some head scratching, but others might have the answer first. We had a day or two of nice weather, and I was out cleaning up flower beds so now I cant move. ? ?
-- don??? va3drl |
开云体育Scott, re? ?V8, I see it is called an FM limiter and AM detector, which is confusing; and now I see that the Plate and Screen voltage is switched by S1-BB? way over …so I believe V8 is switched to function between a FM limiter or an AM detector. The screen and plate voltage are both reduced [some books say 30 volts typical] for operation as a limiter. Perhaps you can measure that that band 5,6 FM ?reduces ? If not, it might have too much gain .? just a thought ? I started looking at the manual and saw that it has a Multiplex out phono jack. You might want to look/listen to the FM audio from there, which is before the switches, then you should know if the problem is in the limiter /discriminator or Not. Likely so, but better to narrow down with confidence. Seems to me, a sweep gen and scope might be needed,? but the usual? look and probe might reveal something ? From: [email protected] [mailto:[email protected]] On Behalf Of Scott Petersen via groups.io
Sent: Monday, March 17, 2025 6:49 PM To: [email protected] Subject: Re: [HallicraftersRadios] SX-62B alignment instructions ? Hi Don, It looks like the area I'm having trouble with, I will study it for a while, I also have trouble with following the signal path. Thanks! going to spend some more time on it tomorrow., We just had corned beef and cabbage, overstuffed... Scott -- don??? va3drl |
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Strange, I routinely use ground connections that are more convenient due to smaller component size and haven't had a problem.? Could be that the new ground connection may not have been a solid connection to the chassis?? Corrosion of rivets and screws in these old radios can make what looks to be a good mechanical connection essentially an open circuit.? Once had a Gonset receiver behave badly until I soldered all of the tube socket ground rings directly to the chassis.? 100 watt American Beauty soldering irons to the rescue!? That is what the girls that assembled the radios originally used.? Obviously this photo was taken before she burnt her finger! The other issue is that if the signal generator output is set too high, the IFT will be over coupled while the AVC will reduce the stage gain which will complicate the alignment even more.? Best to set the radios volume and gain controls to near maximum and set the SG output to as low as needed to do the alignment.? ?This will lead to under coupled IF transformers which will make the IF bandwidth narrow which will improve selectivity.? Technique is important as is understanding of what is happening.? It seems to me that the majority of the problems that we have lately discuss on this forum have been due to rookie errors.?? Shooting oneself in the foot is a common experience, we have all done it.? It is part of the learning curve!? ?<grin> Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Thursday, March 20, 2025 at 09:56:01 AM CDT, Scott Petersen via groups.io <s-petersen@...> wrote:
I re-aligned it and it is pretty good now, I think I shot myself in the foot when I recapped it, I moved a cap to a different ground location, as new caps have shorter leads, and it swung the cap close to the volume control, and crystal filter, which caused
interference while aligning the IF's,
When I found the source was at the cap, I reinstalled it to the original location, and lengthened the lead. This time when I aligned it came out much better, and it is at least usable. Thanks for your help!
From:[email protected] <[email protected]> on behalf of don Root <drootofallevil@...>
Sent:?Wednesday, March 19, 2025 1:12 PM To:[email protected] <[email protected]> Subject:?Re: [HallicraftersRadios] SX-62B alignment instructions ?
Scott, re? ?V8, I see it is called an FM limiter and AM detector, which is confusing; and now I see that the Plate and Screen voltage is switched by S1-BB? way over …so I believe V8 is switched to function between a FM limiter or an AM detector. The screen and plate voltage are both reduced [some books say 30 volts typical] for operation as a limiter. Perhaps you can measure that that band 5,6 FM ?reduces
? If not, it might have too much gain .? just a thought ? I started looking at the manual and saw that it has a Multiplex out phono jack. You might want to look/listen to the FM audio from there, which is before the switches, then you should know if the problem is in the limiter /discriminator or Not. Likely so, but better to narrow down with confidence. Seems to me, a sweep gen and scope might be needed,? but the usual? look and probe might reveal something ?
From:[email protected] [mailto:[email protected]]
On Behalf Of Scott Petersen via groups.io ? Hi Don, It looks like the area I'm having trouble with, I will study it for a while, I also have trouble with following the signal path. Thanks! going to spend some more time on it tomorrow., We just had corned beef and cabbage, overstuffed... Scott -- don??? va3drl |
开云体育Scott, was this cap part of the FM circuit path, and that is why only FM was mucked up? The idea about closeness ?to the volume pot would imply that it was an audio feedback. How did you ever remember where that cap had been grounded? ?? Seems to me early in any restoration, it would be a good idea to verify that each ground terminal has low resistance to the chassis; at least for rivets to chassis. Good that it is working properly now. ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Scott Petersen via groups.io
Sent: Thursday, March 20, 2025 12:54 PM To: [email protected] Subject: Re: [HallicraftersRadios] SX-62B alignment instructions ? The ground was certainly good, but the cap was no longer above the IF transformer. I had to move it closes to the crystal, and volume control, also close to the wiring harness. I just had a thought, maybe the foil side was backwards, and radiated the signals off the outside foil ? From:[email protected] <[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...> ? Strange, I routinely use ground connections that are more convenient due to smaller component size and haven't had a problem.? Could be that the new ground connection may not have been a solid connection to the chassis?? Corrosion of rivets and screws in these old radios can make what looks to be a good mechanical connection essentially an open circuit.? Once had a Gonset receiver behave badly until I soldered all of the tube socket ground rings directly to the chassis.? 100 watt American Beauty soldering irons to the rescue!? That is what the girls that assembled the radios originally used.? Obviously this photo was taken before she burnt her finger! ? ? The other issue is that if the signal generator output is set too high, the IFT will be over coupled while the AVC will reduce the stage gain which will complicate the alignment even more.? Best to set the radios volume and gain controls to near maximum and set the SG output to as low as needed to do the alignment.? ?This will lead to under coupled IF transformers which will make the IF bandwidth narrow which will improve selectivity.? Technique is important as is understanding of what is happening.? It seems to me that the majority of the problems that we have lately discuss on this forum have been due to rookie errors.?? ? Shooting oneself in the foot is a common experience, we have all done it.? It is part of the learning curve!? ?<grin> Jim ? Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy ? ? On Thursday, March 20, 2025 at 09:56:01 AM CDT, Scott Petersen via groups.io <s-petersen@...> wrote: ? ? I re-aligned it and it is pretty good now, I think I shot myself in the foot when I recapped it, I moved a cap to a different ground location, as new caps have shorter leads, and it swung the cap close to the volume control, and crystal filter, which caused interference while aligning the IF's, When I found the source was at the cap, I reinstalled it to the original location, and lengthened the lead. This time when I aligned it came out much better, and it is at least usable. Thanks for your help! ? From:[email protected] <[email protected]> on behalf of don Root <drootofallevil@...> ? Scott, re? ?V8, I see it is called an FM limiter and AM detector, which is confusing; and now I see that the Plate and Screen voltage is switched by S1-BB? way over …so I believe V8 is switched to function between a FM limiter or an AM detector. The screen and plate voltage are both reduced [some books say 30 volts typical] for operation as a limiter. Perhaps you can measure that that band 5,6 FM ?reduces ? If not, it might have too much gain .? just a thought ? I started looking at the manual and saw that it has a Multiplex out phono jack. You might want to look/listen to the FM audio from there, which is before the switches, then you should know if the problem is in the limiter /discriminator or Not. Likely so, but better to narrow down with confidence. Seems to me, a sweep gen and scope might be needed,? but the usual? look and probe might reveal something ? From:[email protected] [mailto:[email protected]] On Behalf Of Scott Petersen via groups.io ? Hi Don, It looks like the area I'm having trouble with, I will study it for a while, I also have trouble with following the signal path. Thanks! going to spend some more time on it tomorrow., We just had corned beef and cabbage, overstuffed... Scott
_._,_._,_ -- don??? va3drl |
开云体育
I remembered because the ground went through the side of the RF shield and I thought "what a dumb way to do a ground" because you have to unsolder the lid of the RF box, just to recap that cap. It came from the first dual can nearest the volume control. it
came off IF T24 to ground.
From: [email protected] <[email protected]> on behalf of don Root <drootofallevil@...>
Sent: Thursday, March 20, 2025 2:17 PM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] SX-62B alignment instructions ?
Scott, was this cap part of the FM circuit path, and that is why only FM was mucked up? The idea about closeness ?to the volume pot would imply that it was an audio feedback. How did you ever remember where that cap had been grounded? ?? Seems to me early in any restoration, it would be a good idea to verify that each ground terminal has low resistance to the chassis; at least for rivets to chassis. Good that it is working properly now. ? ? From: [email protected] [mailto:[email protected]]
On Behalf Of Scott Petersen via groups.io ? The ground was certainly good, but the cap was no longer above the IF transformer. I had to move it closes to the crystal, and volume control, also close to the wiring harness. I just had a thought, maybe the foil side was backwards, and radiated the signals off the outside foil ? From:[email protected]
<[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...> ? Strange, I routinely use ground connections that are more convenient due to smaller component size and haven't had a problem.? Could be that the new ground connection may not have been a solid connection to the chassis?? Corrosion of rivets and screws in these old radios can make what looks to be a good mechanical connection essentially an open circuit.? Once had a Gonset receiver behave badly until I soldered all of the tube socket ground rings directly to the chassis.? 100 watt American Beauty soldering irons to the rescue!? That is what the girls that assembled the radios originally used.? Obviously this photo was taken before she burnt her finger! ?
? The other issue is that if the signal generator output is set too high, the IFT will be over coupled while the AVC will reduce the stage gain which will complicate the alignment even more.? Best to set the radios volume and gain controls to near maximum and set the SG output to as low as needed to do the alignment.? ?This will lead to under coupled IF transformers which will make the IF bandwidth narrow which will improve selectivity.? Technique is important as is understanding of what is happening.? It seems to me that the majority of the problems that we have lately discuss on this forum have been due to rookie errors.?? ? Shooting oneself in the foot is a common experience, we have all done it.? It is part of the learning curve!? ?<grin> Jim ? Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy ? ? On Thursday, March 20, 2025 at 09:56:01 AM CDT, Scott Petersen via groups.io <s-petersen@...> wrote: ? ? I re-aligned it and it is pretty good now, I think I shot myself in the foot when I recapped it, I moved a cap to a different ground location, as new caps have shorter leads, and it swung the cap close to the volume control, and crystal filter, which caused interference while aligning the IF's, When I found the source was at the cap, I reinstalled it to the original location, and lengthened the lead. This time when I aligned it came out much better, and it is at least usable. Thanks for your help! ? From:[email protected]
<[email protected]> on behalf of don Root <drootofallevil@...> ? Scott, re? ?V8, I see it is called an FM limiter and AM detector, which is confusing; and now I see that the Plate and Screen voltage is switched by S1-BB? way over …so I believe V8 is switched to function between a FM limiter or an AM detector. The screen and plate voltage are both reduced [some books say 30 volts typical] for operation as a limiter. Perhaps you can measure that that band 5,6 FM ?reduces ? If not, it might have too much gain .? just a thought ? I started looking at the manual and saw that it has a Multiplex out phono jack. You might want to look/listen to the FM audio from there, which is before the switches, then you should know if the problem is in the limiter /discriminator or Not. Likely so, but better to narrow down with confidence. Seems to me, a sweep gen and scope might be needed,? but the usual? look and probe might reveal something ? From:[email protected] [mailto:[email protected]]
On Behalf Of Scott Petersen via groups.io ? Hi Don, It looks like the area I'm having trouble with, I will study it for a while, I also have trouble with following the signal path. Thanks! going to spend some more time on it tomorrow., We just had corned beef and cabbage, overstuffed... Scott
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don Root
Jim Whartenby