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Hi,
?
I recently did the modification for break-in keying as shown in the Hallicrafters Information Bulletin.
?
I used a separate 10M pot and mounted it in the 3/8” empty hole in the back of the chassis. I installed the 4.7M fixed resistor in series and I did remove the .005mf cap from pin #8 of SO8.
?
The break-in function works as advertised - counterclockwise for shorter delays.
?
However, I do have one issue in that the break-in function is always on. I can not return to normal manual CW operation by turning the pot maximum clockwise as stated.
?
My 10M pot actually measured 8.6M so I tried going up to a 6.8M fixed resistor and that didn’t fix the issue. I also tried a 10M fixed resistor and still had the same issue.
?
I also tried substituting the V14A VOX diode 6AL5 with 3 other spares that I had here and still had the issue.
?
The copy of the bulletin that I have here has a sketch that shows someone using a fixed 22M resistor in place of the normal components resulting in a 2 second delay. I find that interesting in that 22M resistance is certainly beyond the factory’s full clockwise “return to normal manual CW operation” resistance.
?
Has anyone here successfully performed this modification and had if perform as described in the bulletin? Maybe I’m missing something, so I thought I’d ask here.
?
Regards, Alan, W9CG
|
Sorry for so long on the reply but a lot going on here.
Went back through all my notes on my HT-37 build (yes, did build one, another story). My only problem with my build occurred with original power supply problems which had increased the voltages to the VOX circuitry. After correcting those problems, the regular VOX worked as planned.
I did not have a need to try the breakin mod tho knew someone who I believe did with no problems.
Only suspect component I can see is C85, the .22 mfd. If it has gone leaky it would definitely shorten the circuit TC. Be sure your plate voltages meet spec as I have found at least here that Edison is closer to 130 which definitely raise transformer supplies.
Hope this helps, let me know.
73 ... Ed, WA9GQK
On Thursday, March 20, 2025 at 07:05:14 PM CDT, Alan via groups.io <alancgut@...> wrote:
Hi,
?
I recently did the modification for break-in keying as shown in the Hallicrafters Information Bulletin.
?
I used a separate 10M pot and mounted it in the 3/8” empty hole in the back of the chassis. I installed the 4.7M fixed resistor in series and I did remove the .005mf cap from pin #8 of SO8.
?
The break-in function works as advertised - counterclockwise for shorter delays.
?
However, I do have one issue in that the break-in function is always on. I can not return to normal manual CW operation by turning the pot maximum clockwise as stated.
?
My 10M pot actually measured 8.6M so I tried going up to a 6.8M fixed resistor and that didn’t fix the issue. I also tried a 10M fixed resistor and still had the same issue.
?
I also tried substituting the V14A VOX diode 6AL5 with 3 other spares that I had here and still had the issue.
?
The copy of the bulletin that I have here has a sketch that shows someone using a fixed 22M resistor in place of the normal components resulting in a 2 second delay. I find that interesting in that 22M resistance is certainly beyond the factory’s full clockwise “return to normal manual CW operation” resistance.
?
Has anyone here successfully performed this modification and had if perform as described in the bulletin? Maybe I’m missing something, so I thought I’d ask here.
?
Regards, Alan, W9CG
|
Hi Ed,
?
I think I remember something here about someone building an HT-37. I'll have to go back and see if I can find it!
?
Thank-you very much for the suggestions. C85 should be good as I replaced all the paper and electrolytic caps when I went through it several years ago. I'll have to go back and check the voltages, but I seem to remember that I also checked everything to the voltage chart when I went through it. But, unfortunately, I am one of those guys who fails to keep good notes on my work. So, I will check again.
?
Our house line runs pretty consistent around 122 VAC.
?
I already did check all the resistors and everything I could think of in the circuit and have found nothing amiss. I also checked and searched everything on this group and there's not too much conversation at all on this mod. The only thing that I may do if I can't figure it out is to drill a hole for a toggle switch and use it to break that key line if I want to turn it off.
?
Regards,
Alan, W9CG
?
?
?
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Ed Out of curiosity, what voltage do you measure on the 240 volt service line, hot to hot at the circuit breaker panel?? You should read close to 240 volts.? Over 250 volts or so is a problem for your electric service provider to solve.? If one hot to neutral reads 130 vac and the other reads 110 vac then you don't have a solid neutral connection at the circuit breaker panel.??
Is your house wired with copper or aluminum wire? Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
Sorry for so long on the reply but a lot going on here.
Went back through all my notes on my HT-37 build (yes, did build one, another story). My only problem with my build occurred with original power supply problems which had increased the voltages to the VOX circuitry. After correcting those problems, the regular VOX worked as planned.
I did not have a need to try the breakin mod tho knew someone who I believe did with no problems.
Only suspect component I can see is C85, the .22 mfd. If it has gone leaky it would definitely shorten the circuit TC. Be sure your plate voltages meet spec as I have found at least here that Edison is closer to 130 which definitely raise transformer supplies.
Hope this helps, let me know.
73 ... Ed, WA9GQK
On Thursday, March 20, 2025 at 07:05:14 PM CDT, Alan via groups.io <alancgut@...> wrote:
Hi,
?
I recently did the modification for break-in keying as shown in the Hallicrafters Information Bulletin.
?
I used a separate 10M pot and mounted it in the 3/8” empty hole in the back of the chassis. I installed the 4.7M fixed resistor in series and I did remove the .005mf cap from pin #8 of SO8.
?
The break-in function works as advertised - counterclockwise for shorter delays.
?
However, I do have one issue in that the break-in function is always on. I can not return to normal manual CW operation by turning the pot maximum clockwise as stated.
?
My 10M pot actually measured 8.6M so I tried going up to a 6.8M fixed resistor and that didn’t fix the issue. I also tried a 10M fixed resistor and still had the same issue.
?
I also tried substituting the V14A VOX diode 6AL5 with 3 other spares that I had here and still had the issue.
?
The copy of the bulletin that I have here has a sketch that shows someone using a fixed 22M resistor in place of the normal components resulting in a 2 second delay. I find that interesting in that 22M resistance is certainly beyond the factory’s full clockwise “return to normal manual CW operation” resistance.
?
Has anyone here successfully performed this modification and had if perform as described in the bulletin? Maybe I’m missing something, so I thought I’d ask here.
?
Regards, Alan, W9CG
|
Goes back quite a few years so not that relevant for this discussion. Did have Edison out back then and they verified my readings and said it was due to their tweaking the voltage for other customers around here who are still on the older aerial lines with more voltage drop during peak AC season. Those of us on the buried service saw higher voltage. Since then just run my vintage stuff off Variacs set to 115 to save their aged circuitry.
My point was that if VOX circuit voltages are too far off it would affect function. Does not seem that this is the problem for Alan however as he has previously verified voltages. Also seems the mod was done correctly and he has checked the other usual suspects.
Considering the tolerances of components back then the circuit should work unless a component has actually gone bad. I built my rig with many used parts and everything worked ok. Will take a closer look at the whole thing later tomorrow after doing errands.
73 ... Ed
On Monday, March 24, 2025 at 11:43:04 PM CDT, Jim Whartenby via groups.io <old_radio@...> wrote:
Ed Out of curiosity, what voltage do you measure on the 240 volt service line, hot to hot at the circuit breaker panel?? You should read close to 240 volts.? Over 250 volts or so is a problem for your electric service provider to solve.? If one hot to neutral reads 130 vac and the other reads 110 vac then you don't have a solid neutral connection at the circuit breaker panel.??
Is your house wired with copper or aluminum wire? Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
Sorry for so long on the reply but a lot going on here.
Went back through all my notes on my HT-37 build (yes, did build one, another story). My only problem with my build occurred with original power supply problems which had increased the voltages to the VOX circuitry. After correcting those problems, the regular VOX worked as planned.
I did not have a need to try the breakin mod tho knew someone who I believe did with no problems.
Only suspect component I can see is C85, the .22 mfd. If it has gone leaky it would definitely shorten the circuit TC. Be sure your plate voltages meet spec as I have found at least here that Edison is closer to 130 which definitely raise transformer supplies.
Hope this helps, let me know.
73 ... Ed, WA9GQK
On Thursday, March 20, 2025 at 07:05:14 PM CDT, Alan via groups.io <alancgut@...> wrote:
Hi,
?
I recently did the modification for break-in keying as shown in the Hallicrafters Information Bulletin.
?
I used a separate 10M pot and mounted it in the 3/8” empty hole in the back of the chassis. I installed the 4.7M fixed resistor in series and I did remove the .005mf cap from pin #8 of SO8.
?
The break-in function works as advertised - counterclockwise for shorter delays.
?
However, I do have one issue in that the break-in function is always on. I can not return to normal manual CW operation by turning the pot maximum clockwise as stated.
?
My 10M pot actually measured 8.6M so I tried going up to a 6.8M fixed resistor and that didn’t fix the issue. I also tried a 10M fixed resistor and still had the same issue.
?
I also tried substituting the V14A VOX diode 6AL5 with 3 other spares that I had here and still had the issue.
?
The copy of the bulletin that I have here has a sketch that shows someone using a fixed 22M resistor in place of the normal components resulting in a 2 second delay. I find that interesting in that 22M resistance is certainly beyond the factory’s full clockwise “return to normal manual CW operation” resistance.
?
Has anyone here successfully performed this modification and had if perform as described in the bulletin? Maybe I’m missing something, so I thought I’d ask here.
?
Regards, Alan, W9CG
|
Ed This is surprising.? The maximum service line voltage is 126 volts per ANSI C84.1.? This maximum line voltage has not changed at all since it was first published in 1954.? This is when the 120 volt ac line voltage convention was adopted.? The two previous line voltage conventions are 115 volts +/- 10% issued in 1926 and 117 volts +/- 7.5% issued around the beginning of WW2.
The only voltage that really matters in tube powered equipment is the heater voltage.? The mean voltage for most common tubes is 6.3 volts with a voltage tolerance of +/- 10%.? Best performance is at 6.3 volts, longest life is at a lower heater voltage but at the price of lower cathode emission, shorter life is at a higher heater voltage which will have higher cathode emission.? For receiving tubes perhaps one will not notice much difference over the +/- 10% heater voltage tolerance.? Power tubes, perhaps over a 100 watts dissipation,? are a different matter and most manufacturers specify a tighter control of heater voltage, usually +/- 5%.? ?This just happens to be the same tolerance as the present 120 volt line voltage convention.
Measure your heater voltage.? If it is within a few percent of nominal, then all is OK and you won't have to by any more VARIACs! Regards, Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
Goes back quite a few years so not that relevant for this discussion. Did have Edison out back then and they verified my readings and said it was due to their tweaking the voltage for other customers around here who are still on the older aerial lines with more voltage drop during peak AC season. Those of us on the buried service saw higher voltage. Since then just run my vintage stuff off Variacs set to 115 to save their aged circuitry.
My point was that if VOX circuit voltages are too far off it would affect function. Does not seem that this is the problem for Alan however as he has previously verified voltages. Also seems the mod was done correctly and he has checked the other usual suspects.
Considering the tolerances of components back then the circuit should work unless a component has actually gone bad. I built my rig with many used parts and everything worked ok. Will take a closer look at the whole thing later tomorrow after doing errands.
73 ... Ed
On Monday, March 24, 2025 at 11:43:04 PM CDT, Jim Whartenby via groups.io <old_radio@...> wrote:
Ed Out of curiosity, what voltage do you measure on the 240 volt service line, hot to hot at the circuit breaker panel?? You should read close to 240 volts.? Over 250 volts or so is a problem for your electric service provider to solve.? If one hot to neutral reads 130 vac and the other reads 110 vac then you don't have a solid neutral connection at the circuit breaker panel.??
Is your house wired with copper or aluminum wire? Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
Sorry for so long on the reply but a lot going on here.
Went back through all my notes on my HT-37 build (yes, did build one, another story). My only problem with my build occurred with original power supply problems which had increased the voltages to the VOX circuitry. After correcting those problems, the regular VOX worked as planned.
I did not have a need to try the breakin mod tho knew someone who I believe did with no problems.
Only suspect component I can see is C85, the .22 mfd. If it has gone leaky it would definitely shorten the circuit TC. Be sure your plate voltages meet spec as I have found at least here that Edison is closer to 130 which definitely raise transformer supplies.
Hope this helps, let me know.
73 ... Ed, WA9GQK
On Thursday, March 20, 2025 at 07:05:14 PM CDT, Alan via groups.io <alancgut@...> wrote:
Hi,
?
I recently did the modification for break-in keying as shown in the Hallicrafters Information Bulletin.
?
I used a separate 10M pot and mounted it in the 3/8” empty hole in the back of the chassis. I installed the 4.7M fixed resistor in series and I did remove the .005mf cap from pin #8 of SO8.
?
The break-in function works as advertised - counterclockwise for shorter delays.
?
However, I do have one issue in that the break-in function is always on. I can not return to normal manual CW operation by turning the pot maximum clockwise as stated.
?
My 10M pot actually measured 8.6M so I tried going up to a 6.8M fixed resistor and that didn’t fix the issue. I also tried a 10M fixed resistor and still had the same issue.
?
I also tried substituting the V14A VOX diode 6AL5 with 3 other spares that I had here and still had the issue.
?
The copy of the bulletin that I have here has a sketch that shows someone using a fixed 22M resistor in place of the normal components resulting in a 2 second delay. I find that interesting in that 22M resistance is certainly beyond the factory’s full clockwise “return to normal manual CW operation” resistance.
?
Has anyone here successfully performed this modification and had if perform as described in the bulletin? Maybe I’m missing something, so I thought I’d ask here.
?
Regards, Alan, W9CG
|
I did the mod according to the sketch you mentioned, which I happened to see stuck inside the manual when I bought the old HT37. It didn't work for me, so I took it out, So far I haven't been able to find a way to use the HT 37 on CW without wearing out the front panel switch.? It works great on CW, but the manual switching regularly will wear the switch out plus it's a lot of trouble.? I would love to use it on CW but cannot find an easy way.
?
K4ZDH
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Jim Whartenby