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S-38 Questions about alignment.
I am restoring now aligning a S-38. Yep, all caps and resistors replaced
except the domino caps and tubes tested, bias voltages with in spec. I gave up the alignment for now. I am having trouble aligning the Band 2 at 5mc. The oscillator just dose not want to go high enough. Perhaps a good night's sleep will help. Questions: 1) What is the oscillator offset (add or subtract the IF freq 455) for the four bands? Are any bands different from the others? Broadcast is just fine at frequency plus IF (455). 2) Are the domino caps paper inside or mica? They are NOT Micamold. There are three of four of them. I was going to replace them next and heat gun the coils. http://www.nostalgiaair.org/PagesByM...2/M0008862.pdf Thanks, Paul P |
S-38 Questions about alignment.
On Apr 13, 6:40*pm, "Paul P" REMOVE paul @ REMOVE ppinyot .
REMOVEcom wrote: I am restoring now aligning a S-38. *Yep, all caps and resistors replaced except the domino caps and tubes tested, bias voltages with in spec. *I gave up the alignment for now. *I am having trouble aligning the Band 2 at 5mc. The oscillator just dose not want to go high enough. *Perhaps a good night's sleep will help. Questions: 1) What is the oscillator offset (add or subtract the IF freq 455) for the four bands? *Are any bands different from the others? *Broadcast is just fine at frequency plus IF (455). 2) Are the domino caps paper inside or mica? *They are NOT Micamold. *There are three of four of them. *I was going to replace them next and heat gun the coils. http://www.nostalgiaair.org/PagesByM...2/M0008862.pdf Thanks, Paul P The postage stamp caps are mica but probably not silver mica. If all the other frequencies come in the problem may be that something has shifted in the band 2 oscillator coil. Most of these coils have a couple of spaced turns to adjust the value. You will have to juggle between the coil and the trimmer. The S-38B LO is 455 khz above the signal frequency on all bands. |
S-38 Questions about alignment.
"Richard Knoppow" wrote in message ... On Apr 13, 6:40 pm, "Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote: I am restoring now aligning a S-38. Yep, all caps and resistors replaced except the domino caps and tubes tested, bias voltages with in spec. I gave up the alignment for now. I am having trouble aligning the Band 2 at 5mc. The oscillator just dose not want to go high enough. Perhaps a good night's sleep will help. Questions: 1) What is the oscillator offset (add or subtract the IF freq 455) for the four bands? Are any bands different from the others? Broadcast is just fine at frequency plus IF (455). 2) Are the domino caps paper inside or mica? They are NOT Micamold. There are three of four of them. I was going to replace them next and heat gun the coils. http://www.nostalgiaair.org/PagesByM...2/M0008862.pdf Thanks, Paul P The postage stamp caps are mica but probably not silver mica. If all the other frequencies come in the problem may be that something has shifted in the band 2 oscillator coil. Most of these coils have a couple of spaced turns to adjust the value. You will have to juggle between the coil and the trimmer. The S-38B LO is 455 khz above the signal frequency on all bands.\ Thanks Richard, Yes the whole band is shifted. I will look at and chase the coils. One point of clarification. So that would make 5 MHz look like 5.455MHz on the oscilator? Paul P. KB3LZP |
S-38 Questions about alignment.
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in message ... "Richard Knoppow" wrote in message ... On Apr 13, 6:40 pm, "Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote: I am restoring now aligning a S-38. Yep, all caps and resistors replaced except the domino caps and tubes tested, bias voltages with in spec. I gave up the alignment for now. I am having trouble aligning the Band 2 at 5mc. The oscillator just dose not want to go high enough. Perhaps a good night's sleep will help. Questions: 1) What is the oscillator offset (add or subtract the IF freq 455) for the four bands? Are any bands different from the others? Broadcast is just fine at frequency plus IF (455). 2) Are the domino caps paper inside or mica? They are NOT Micamold. There are three of four of them. I was going to replace them next and heat gun the coils. http://www.nostalgiaair.org/PagesByM...2/M0008862.pdf Thanks, Paul P The postage stamp caps are mica but probably not silver mica. If all the other frequencies come in the problem may be that something has shifted in the band 2 oscillator coil. Most of these coils have a couple of spaced turns to adjust the value. You will have to juggle between the coil and the trimmer. The S-38B LO is 455 khz above the signal frequency on all bands.\ Thanks Richard, Yes the whole band is shifted. I will look at and chase the coils. One point of clarification. So that would make 5 MHz look like 5.455MHz on the oscilator? Paul P. KB3LZP Exactly. Looking at the schematic it appears that bands 1 and 2 have fixed padders in them. For Band-2 its C-11, a 2200 mmf cap and probably one of the postage stamps. If this has changed value it will throw off the band. I think this is more likely than the coil having shifted. This is a common value so a replacement should not be hard to find. I suggest changing it before doing anything else. -- Richard Knoppow Los Angeles WB6KBL |
S-38 Questions about alignment.
Richard Knoppow wrote:
Looking at the schematic it appears that bands 1 and 2 have fixed padders in them. For Band-2 its C-11, a 2200 mmf cap and probably one of the postage stamps. If this has changed value it will throw off the band. I think this is more likely than the coil having shifted. This is a common value so a replacement should not be hard to find. I suggest changing it before doing anything else. Trying to follow your posts across the different forums. The 38 is a plain jane AA5 with shortwave bands, Don't try to read too much into it. Image rejection is so poor on the top band that it really makes little difference as to how you tune it. You're welcome to try, though. |
S-38 Questions about alignment.
On Apr 14, 6:38*pm, Bill M wrote:
Richard Knoppow wrote: * * Looking at the schematic it appears that bands 1 and 2 have fixed padders in them. For Band-2 its C-11, a 2200 mmf cap and probably one of the postage stamps. If this has changed value it will throw off the band. I think this is more likely than the coil having shifted. This is a common value so a replacement should not be hard to find. I suggest changing it before doing anything else. Trying to follow your posts across the different forums. The 38 is a plain jane AA5 with shortwave bands, *Don't try to read too much into it. *Image rejection is so poor on the top band that it really makes little difference as to how you tune it. *You're welcome to try, though. I'm glad you wrote because I mistook the band Paul was trying to align. Its band -3 which does not have a padder. So, if nothing else seems wrong the coil may need tweeking. I am pretty sure all the bands on the S-38 series tune with the LO above the signal frequency. One can always try it below. If that's wrong it won't track properly. I don't think it has any image rejection at the upper part of the top band:-) Richard Knoppow WB6KBL |
S-38 Questions about alignment.
"Richard Knoppow" wrote in message ... On Apr 14, 6:38 pm, Bill M wrote: Richard Knoppow wrote: Looking at the schematic it appears that bands 1 and 2 have fixed padders in them. For Band-2 its C-11, a 2200 mmf cap and probably one of the postage stamps. If this has changed value it will throw off the band. I think this is more likely than the coil having shifted. This is a common value so a replacement should not be hard to find. I suggest changing it before doing anything else. Trying to follow your posts across the different forums. The 38 is a plain jane AA5 with shortwave bands, Don't try to read too much into it. Image rejection is so poor on the top band that it really makes little difference as to how you tune it. You're welcome to try, though. I'm glad you wrote because I mistook the band Paul was trying to align. Its band -3 which does not have a padder. So, if nothing else seems wrong the coil may need tweeking. I am pretty sure all the bands on the S-38 series tune with the LO above the signal frequency. One can always try it below. If that's wrong it won't track properly. I don't think it has any image rejection at the upper part of the top band:-) Richard Knoppow WB6KBL Gentlemen, A point of clarification: Band 2 is the problematic band. It covers 1.650 to 5 MHz. The 5MHz is the oscillator set point. The padder is to be set at 1.8MHz and does not even come close with the difference at the 5MHz Osc Trimmer error. This band is aligned after the 455 IF, BFO and two higher bands are aligned. After this band is the standard broadcast band. The padder C11 on band 2 is a variable cap with a postage stamp (domino) in parallel. I disconnected this parallel cap in hopes of raising the overall oscillator frequency to align to 5MHz with no success. It barely made a difference (no big surprise here). The other bands align properly starting with Band 4, 13.5 - 32 MHz, band 3, 5 - 14.5 MHz and last band 1 broadcast. I will also check C9 (2700 or 3000pf) in series with the tuning gang on a hunch. It may have some low end affects. I did not attempt to calculate the low end cut off point (collage was too long ago). The band spread has been set to Zero in accordance to the alignment procedure page 15-62. I did use carbon composition resistors in front of the first IF for Rs 1, 2, 3, 20 & 21. I will try all the suggestions today. I spoke with the owner yesterday. He wound up in the hospital with a chainsaw gouge in his leg. He and another were at our ham club cutting trees and had an accident. I want to get this chassis working great for him. Your help is helpful. As always, thanks for all the input! Paul P. |
S-38 Questions about alignment.
Paul P wrote:
Band 2 is the problematic band. It covers 1.650 to 5 MHz. The 5MHz is the oscillator set point. The padder is to be set at 1.8MHz and does not even come close with the difference at the 5MHz Osc Trimmer error. This band is aligned after the 455 IF, BFO and two higher bands are aligned. After this band is the standard broadcast band. The padder C11 on band 2 is a variable cap with a postage stamp (domino) in parallel. I disconnected this parallel cap in hopes of raising the overall oscillator frequency to align to 5MHz with no success. It barely made a difference (no big surprise here). The other bands align properly starting with Band 4, 13.5 - 32 MHz, band 3, 5 - 14.5 MHz and last band 1 broadcast. Are you able to get the 5Mc point set ok? Sometimes the solution is to fudge on the dial pointer alignment and see if the other 3 bands can line up. However, if they are spot on now that might not be the direction to go. -Bill |
S-38 Questions about alignment.
"Bill M" wrote in message ... Paul P wrote: Band 2 is the problematic band. It covers 1.650 to 5 MHz. The 5MHz is the oscillator set point. The padder is to be set at 1.8MHz and does not even come close with the difference at the 5MHz Osc Trimmer error. This band is aligned after the 455 IF, BFO and two higher bands are aligned. After this band is the standard broadcast band. The padder C11 on band 2 is a variable cap with a postage stamp (domino) in parallel. I disconnected this parallel cap in hopes of raising the overall oscillator frequency to align to 5MHz with no success. It barely made a difference (no big surprise here). The other bands align properly starting with Band 4, 13.5 - 32 MHz, band 3, 5 - 14.5 MHz and last band 1 broadcast. Are you able to get the 5Mc point set ok? Sometimes the solution is to fudge on the dial pointer alignment and see if the other 3 bands can line up. However, if they are spot on now that might not be the direction to go. -Bill I have done this before on other chassis. This chassis has hard stops at the dial scale extremes. Moving the pointer will throw the pointer off where it will not cover the band scale edge. This would be unacceptable on this chassis. I can not get the 5Mc aligned. It is fairly far off uniformly across the whole band. All other bands are dead on the marks. I am Climbing The Stairway to Heaven (the shop/shack) at this time. I will report back later. Thanks Bill, Paul P. |
S-38 Questions about alignment.
Paul P wrote:
I can not get the 5Mc aligned. It is fairly far off uniformly across the whole band. All other bands are dead on the marks. Ah, ok. Now I'm on board. No point in fussing with the padder yet, then. Things may fall into place once you get the top end of the band right. Just for grins, will the oscillator tune to the lower side (4545)? I don't *think* it should be that way but ya never know. -Bill |
S-38 Questions about alignment.
"Bill M" wrote in message ... Paul P wrote: Band 2 is the problematic band. It covers 1.650 to 5 MHz. The 5MHz is the oscillator set point. The padder is to be set at 1.8MHz and does not even come close with the difference at the 5MHz Osc Trimmer error. This band is aligned after the 455 IF, BFO and two higher bands are aligned. After this band is the standard broadcast band. The padder C11 on band 2 is a variable cap with a postage stamp (domino) in parallel. I disconnected this parallel cap in hopes of raising the overall oscillator frequency to align to 5MHz with no success. It barely made a difference (no big surprise here). The other bands align properly starting with Band 4, 13.5 - 32 MHz, band 3, 5 - 14.5 MHz and last band 1 broadcast. Are you able to get the 5Mc point set ok? Sometimes the solution is to fudge on the dial pointer alignment and see if the other 3 bands can line up. However, if they are spot on now that might not be the direction to go. -Bill Should not have to fudge anything. The top and bottom bands are good so the Oscillator is good. The 5 mc band is off so there is a bad part connected to the band switch. Fix or replace. Fudging always makes more problems. I had an S-120 growing up http://image08.webshots.com/8/8/80/8...3yhLWvj_fs.jpg and later, S-38E for show. http://www.woulfeman.com/Radio%20Hallicrafters.jpg I was SWL long before I got around to the ham ticket. |
Fixed!
Should not have to fudge anything. The top and bottom bands are good so
the Oscillator is good. The 5 mc band is off so there is a bad part connected to the band switch. Fix or replace. Fudging always makes more problems. I had an S-120 growing up http://image08.webshots.com/8/8/80/8...3yhLWvj_fs.jpg and later, S-38E for show. http://www.woulfeman.com/Radio%20Hallicrafters.jpg I was SWL long before I got around to the ham ticket. JB was the closest. After fussing with it for another two hours I started tracing the padders on each band. What I found was very curios. There was a rather original looking wire connected from the band 2 osc trimmer (coil lug 20, see schematic) to one of the antenna coils (tab O on the wafer switch). Why that was put there? I have not a clue. Once I disconnected the trimmer side of the wire the oscillator snapped back into alignment range. It tweaked in at both the 5Mc and 1.8Mc alignment points dead nuts on. I desoldered the switch side of the jumper (tab O). The joint looked rather factory and not owner installed. Curious. The Trimmer side (coil lug 20) was definitely messed with (short lead and burned insulation). Ham owned gear. It's like a box of chocolates. Ya never know what you will find. Thanks to all for the comments. They did help focus me on the band 2 circuit. Paul P. |
Fixed!
Paul P wrote:
There was a rather original looking wire connected from the band 2 osc trimmer (coil lug 20, see schematic) to one of the antenna coils (tab O on the wafer switch). Why that was put there? I have not a clue. Once I disconnected the trimmer side of the wire the oscillator snapped back into alignment range. It tweaked in at both the 5Mc and 1.8Mc alignment points dead nuts on. Amazing! Kudos for finding it. -Bill |
Fixed!
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in message ... Should not have to fudge anything. The top and bottom bands are good so the Oscillator is good. The 5 mc band is off so there is a bad part connected to the band switch. Fix or replace. Fudging always makes more problems. I had an S-120 growing up http://image08.webshots.com/8/8/80/8...3yhLWvj_fs.jpg and later, S-38E for show. http://www.woulfeman.com/Radio%20Hallicrafters.jpg I was SWL long before I got around to the ham ticket. JB was the closest. After fussing with it for another two hours I started tracing the padders on each band. What I found was very curios. There was a rather original looking wire connected from the band 2 osc trimmer (coil lug 20, see schematic) to one of the antenna coils (tab O on the wafer switch). Why that was put there? I have not a clue. Once I disconnected the trimmer side of the wire the oscillator snapped back into alignment range. It tweaked in at both the 5Mc and 1.8Mc alignment points dead nuts on. I desoldered the switch side of the jumper (tab O). The joint looked rather factory and not owner installed. Curious. The Trimmer side (coil lug 20) was definitely messed with (short lead and burned insulation). Ham owned gear. It's like a box of chocolates. Ya never know what you will find. Thanks to all for the comments. They did help focus me on the band 2 circuit. Paul P. Congratulations!!! I was about to post another answer because I find that only the S-38 had a padder on this band, the S-38A and B have just the 2200 uuf fixed padder. As you say, who knows what that person thought they were doing. If the owner plays around with chain saws I can understand why you wanted to please him. -- Richard Knoppow Los Angeles WB6KBL |
Fixed!
If the owner plays around with chain saws I can understand why you wanted to please him. -- Richard Knoppow Los Angeles WB6KBL Yes. I should be seeing him today. He is an very active member of the Skyview Radio Society ham club. He (and others) do a lot to promote Ham Radio. He tried to talk the nurses into a VE session and getting their license. Paul P. |
S-38 Questions about alignment.
OK then I wasn't wrong about which band was the problem:-) However, in
the Rider's manual from Nostalgia Radio C-11 is shown as a fixed 2200 uuf cap. I also found a PDF of the original Hallicrafters handbook. This also shows a 2200 uuf fixed cap in the padder position. The component numbers are different from the Rider's sheets, in the Hallicrafter's book this cap is called C-16 and is listed as a 600V mica. For band-2 the only adjustment is the trimmer, C-21 (in the H book). If the low end is off or if the entire band is off I suspect C-21 or else coil damage. The S-38 does have an adjustable padder for Band-2 but the S-38A and S-38B do not. So, I suspect someone added the adjustable cap for some reason, perhaps because of the problem you are having. Anyway. I would remove it, put a 2200 uuf mica cap there and see what you get. If the thing is still off check the coils and value of the trimmer, maybe someone substituted it. -- Richard Knoppow Los Angeles WB6KBL Richard, Where did you find that manual? As a side note, if you look at the Nostalgia Air schematic it does show a padder on the band 2 position and it is bolted on the chassis with access holes from the top. Band 2 does have a 1200pf cap in parallel with the padder that is needed to align the 1.8Mc point. That cap is NOT depicted on the schematic. The padder does look factory as do the holes, wires and bolt through the chassis. And thanks again for all the comments and help, Thanks, Paul P. |
Fixed: picture of the failure.
The culprit: http://www.ppinyot.com/H/Hallicrafte...8straywire.JPG
The rest of the story: http://www.ppinyot.com/s-38.htm Paul P. |
Fixed!
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in message
... Should not have to fudge anything. The top and bottom bands are good so the Oscillator is good. The 5 mc band is off so there is a bad part connected to the band switch. Fix or replace. Fudging always makes more problems. I had an S-120 growing up http://image08.webshots.com/8/8/80/8...3yhLWvj_fs.jpg and later, S-38E for show. http://www.woulfeman.com/Radio%20Hallicrafters.jpg I was SWL long before I got around to the ham ticket. JB was the closest. After fussing with it for another two hours I started tracing the padders on each band. What I found was very curios. There was a rather original looking wire connected from the band 2 osc trimmer (coil lug 20, see schematic) to one of the antenna coils (tab O on the wafer switch). Why that was put there? I have not a clue. Once I disconnected the trimmer side of the wire the oscillator snapped back into alignment range. It tweaked in at both the 5Mc and 1.8Mc alignment points dead nuts on. I desoldered the switch side of the jumper (tab O). The joint looked rather factory and not owner installed. Curious. The Trimmer side (coil lug 20) was definitely messed with (short lead and burned insulation). Ham owned gear. It's like a box of chocolates. Ya never know what you will find. Thanks to all for the comments. They did help focus me on the band 2 circuit. Paul P. Occasionally I find some equipment that never worked from the factory and so escaped much wear and tear, being passed from one shelf to another. After I acquire it for a song, I find a quality control issue. I got my IFR that way. |
S-38 Questions about alignment.
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in message ... OK then I wasn't wrong about which band was the problem:-) However, in the Rider's manual from Nostalgia Radio C-11 is shown as a fixed 2200 uuf cap. I also found a PDF of the original Hallicrafters handbook. This also shows a 2200 uuf fixed cap in the padder position. The component numbers are different from the Rider's sheets, in the Hallicrafter's book this cap is called C-16 and is listed as a 600V mica. For band-2 the only adjustment is the trimmer, C-21 (in the H book). If the low end is off or if the entire band is off I suspect C-21 or else coil damage. The S-38 does have an adjustable padder for Band-2 but the S-38A and S-38B do not. So, I suspect someone added the adjustable cap for some reason, perhaps because of the problem you are having. Anyway. I would remove it, put a 2200 uuf mica cap there and see what you get. If the thing is still off check the coils and value of the trimmer, maybe someone substituted it. -- Richard Knoppow Los Angeles WB6KBL Richard, Where did you find that manual? As a side note, if you look at the Nostalgia Air schematic it does show a padder on the band 2 position and it is bolted on the chassis with access holes from the top. Band 2 does have a 1200pf cap in parallel with the padder that is needed to align the 1.8Mc point. That cap is NOT depicted on the schematic. The padder does look factory as do the holes, wires and bolt through the chassis. And thanks again for all the comments and help, Thanks, Paul P. Its on BAMA. I usually use the mirror site because its much faster most of the time. See http://bama.edebris.com/manuals/hallicra/s38b/ There is also a Sam's folder in the same place. I suspect Hallicrafters made a lot of undocumented changes at various times. The S-38 has a padder on the second band but it faces the bottom. I have both an S-38 and S-38B in the hopper except the S-38B is in one of a couple of storage garages and I no longer remember where. This was my first short wave receiver bought by my parents new after a great deal of nagging. I think I have become a defacto Hallicrafters collector without meaning to. -- Richard Knoppow Los Angeles WB6KBL |
Fixed!
On Apr 16, 9:36*am, "JB" wrote:
Occasionally I find some equipment that never worked from the factory and so escaped much wear and tear, being passed from one shelf to another. *After I acquire it for a song, I find a quality control issue. *I got my IFR that way.- Hide quoted text - - Show quoted text - I agree with that! I have picked up several pieces of equipment that are 'like new' but have some subtle problem. Usually it is a small error with large effect on operation. Does not say much for factory QA!! Neil S. |
Fixed: picture of the failure.
"Paul P" REMOVE paul @ REMOVE ppinyot . REMOVEcom wrote in message ... The culprit: http://www.ppinyot.com/H/Hallicrafte...8straywire.JPG The rest of the story: http://www.ppinyot.com/s-38.htm Paul P. Aha... This is NOT an S-38B, its an S-38. The S-38 has an adjustable BFO, none of the later versions do. No wonder the schematics seemed wrong, they _were_. I opened my S-38 to double check and the wire you indicate in the photo is NOT there so this was definitely someone's add on. It would be interesing to trace this out and try to figure out what they thought they were doing. I have to get at my RX soon, needs a cleaning and some new caps. BTW does anyone know of a source for Hallicrafters knobs of the right vintage for this RX and the S-40 series, etc? I've had no success at all in trying to find any. -- Richard Knoppow Los Angeles WB6KBL |
Fixed: picture of the failure.
Richard Knoppow wrote:
BTW does anyone know of a source for Hallicrafters knobs of the right vintage for this RX and the S-40 series, etc? I've had no success at all in trying to find any. Try Larry Bordonaro. I got some for my S-40A from him but that has been several years ago. Contact info can be found at: http://www.antiqueradioknobs.com/ |
Fixed: picture of the failure.
"Bill M" wrote in message ... Richard Knoppow wrote: BTW does anyone know of a source for Hallicrafters knobs of the right vintage for this RX and the S-40 series, etc? I've had no success at all in trying to find any. Try Larry Bordonaro. I got some for my S-40A from him but that has been several years ago. Contact info can be found at: http://www.antiqueradioknobs.com/ Thanks, I'll try him. -- Richard Knoppow Los Angeles WB6KBL |
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