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Re: Taming a VFO - HT46
开云体育Jerry, ? I found a 82pF, N080 capacitor in my parts “inventory”, it seems to be NOS, but it test at 92pF. See attached. If ever you may need it, just send me your mail address, in case that Canada Post strike ends soon enough… ? 73, Jacques, VE2JFE in Montreal ? It looks like the problem was one of those big offenders you mentioned Walt. Specifically C85 82pfN80. It measures 82pf but seems to have lost it's temperature compensation characteristics. Now the challenge is finding a replacement.?? Surplus Sales of Nebraska seems to be the only supplier of tubular capacitors but they don't have much in that range. I considered trying a Class 1 disk ceramic but most of those are NP0 or N750. My junk box produced a 62pfN150 and I have been playing with a series and parallel NP0 to get in the ball park. That is pretty crude, not a permanent solution and I'm still not where I need to be with the drift problem. Back to googling "dogbone" "tubular ceramic" "temperature compensating capacitor" etc.? |
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Re: Taming a VFO - HT46
开云体育
I have found that 82pf N80 difficult to find also. I have successfully used an 82pf N30 as a replacement.
I have a couple left. If you have no luck finding?an N80 shoot me an email at
cateswa at msn dot com.
Walt Cates, WD0GOF
?
From: [email protected] <[email protected]> on behalf of W0PWE via groups.io <j.b.hall@...>
Sent: Wednesday, December 4, 2024 9:09 AM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Taming a VFO - HT46 ?
It looks like the problem was one of those big offenders you mentioned Walt. Specifically C85 82pfN80. It measures 82pf but seems to have lost it's temperature compensation characteristics. Now the challenge is finding a replacement.?
?
Surplus Sales of Nebraska seems to be the only supplier of tubular capacitors but they don't have much in that range. I considered trying a Class 1 disk ceramic but most of those are NP0 or N750. My junk box produced a 62pfN150 and I have been playing
with a series and parallel NP0 to get in the ball park. That is pretty crude, not a permanent solution and I'm still not where I need to be with the drift problem. Back to googling "dogbone" "tubular ceramic" "temperature compensating capacitor" etc.?
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Re: Identify transformer
开云体育Richard, ???The old formula I learned is X= 2πfL. ?for 60 cycles--- ?6.28 *60* 12 = ??4521.6 ?[a lot of X-ohms ?] ?compared to 85 R-ohms, but that must be the magnetizing inductance at some low voltage. ? yes turns ratio measured by voltage ratio would help From: [email protected] [mailto:[email protected]] On Behalf Of Richard Knoppow via groups.io
Sent: Monday, December 2, 2024 6:11 PM To: [email protected] Subject: Re: [HallicraftersRadios] Identify transformer ? This is still an odd transformer. There have been systems of color -- don??? va3drl |
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Re: Identify transformer
开云体育Walt and Jim and All Black wires in and red wires out remind me of typical B+ ?power transformers. B+ for transistors were low voltage back then, so maybe ?you have a low voltage B+ rectifier transformer ,[ and no heaters needed]. Trial#1---- R.Pri? =85??? R.sec tot = .3+.3 = .6 ?Res ratio [P/S]?? 85 /? 0.6=? ??141??????? and?????? ??Similar X ratio? 12/.06 = 200 ? Turns ratio calculated from Res ratio [simplified assumptions ] = ???√141?? = a bit under 12, so use 12 ? Assume 120 v primary,? so secondary = 120/ 12? =? 10V C.T. ? I was looking at Filament and rectifier transformers in a 1974 Hammond catalog? 150 VA was 7.5 Lbs So that’s my guess until Jim reverses my mental gymnastics ? ? From: [email protected] [mailto:[email protected]] On Behalf Of waltcates via groups.io
Sent: Monday, December 2, 2024 3:13 PM To: [email protected] Subject: Re: [HallicraftersRadios] Identify transformer ? Jim, ? That list you attached came from my website. That is what is so confusing about this hunk of iron. Those colors don't match any standard.? ?? ?
?
_._,_._,_ -- don??? va3drl |
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Re: Taming a VFO - HT46
开云体育
Jerry,
I looked up some of my old repair tickets from the 90's. I found some other things you may try. Chassis corrosion and grounding were problems on several tickets.?
Remove the mounting screws of C83 one at a time, clean the chassis around the hole and give the hole and screw a shot of DeOxit, insure there is a star lock washer under each screw.
Remove the mounting nut on L24, clean the chassis, L24 mounting surface and the retaining nut. There should also be a lock washer between the nut and the chassis.
That is all I have on the drift problem.?
Walt Cates, WD0GOF
?
From: [email protected] <[email protected]> on behalf of W0PWE via groups.io <j.b.hall@...>
Sent: Monday, December 2, 2024 12:17 PM To: [email protected] <[email protected]> Subject: [HallicraftersRadios] Taming a VFO - HT46 ?
The VFO in my newest HT46 has excessive drift. In standby mode it will drift about 1KHz in the first 15 minutes and then go another 600Hz in the following hour. The VFO drifts downward in frequency so it appears as though the capacitance in the tuned circuit needs more NEGATIVE temperature coefficient. It has a 10pfN750 and an 82pfN80 capacitor for compensation but they aren’t quite doing the job. ? Following some work by W7ZOI I have experimented with some different series combinations of N750 and NP0 capacitors in place of the 10pfN750. I have reduced the drift to about 10Hz/C but the series combination that produced that adds too much total capacitance to the circuit so it is not a solution. Experimental results and a few calculations would indicate I need a 10pfN1285 capacitor but of course that will be difficult to achieve. ? What bothers me about all this is that I have two other VFOs of this design - one in an SX146 receiver and the other in an old beat up and abused HT46. Both those VFOs have negligible drift. I have checked and re-checked the components in the offending VFO and I have compared them to what is in the well behaved HT46. Hopefully someone has experience with this or knows about a common cause for such behavior. 73 – Jerry – W0PWE ? |
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Re: Identify transformer
Walt You can always apply 12VAC to the black leads and measure what what is on the red leads.? Still feel that it is an AC step down power transformer. You should put your call on that document.? Always sign your work! Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Monday, December 2, 2024 at 02:12:56 PM CST, waltcates via groups.io <cateswa@...> wrote:
Jim,
That list you attached came from my website. That is what is so confusing about this hunk of iron. Those colors don't match any standard.? ??
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.
From: [email protected] <[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...>
Sent: Monday, December 2, 2024 2:48 PM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Identify transformer ?
All thing are possible since transformers are bilateral.? Typically, audio transformers do not use two black leads or two red leads for that matter and the laminations are usually thinner then those for AC power transformers.
OUTPUT TRANSFORMERS ARRL Radio Amateur's Handbook:?
Single-ended transformers:?
Plate lead (pri.) -------------- blue (or brown)?
B+ (power supply) lead --------- red?
speaker (typ. +) (sec.) -------- green (or yellow)?
speaker return (sec.) ---------- black?
I found the above info on the web, don't know who wrote it.? The full file is attached.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Monday, December 2, 2024 at 08:36:36 AM CST, waltcates via groups.io <cateswa@...> wrote:
Flip the drawing and you could have a push pull amp driving another stage.
Walt Cates,
WD0GOF
?
A majority of acceptance is not proof of correctness.
From: [email protected] <[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...>
Sent: Monday, December 2, 2024 3:15 AM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Identify transformer ?
Don
With a primary resistance of 85 ohms @ 12 Henrys and a secondary resistance of 0.6 ohms @ 0.055 Henrys how could this possibly be a step-up power transformer?? At 7 pounds, I would guess it would have a rating of perhaps 150 V-A.? So if the full
secondary is around 24 volts, the current would be around 6 amps.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Sunday, December 1, 2024 at 08:07:04 PM CST, don Root <drootofallevil@...> wrote:
Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ?
From: [email protected] [mailto:[email protected]]
On Behalf Of waltcates via groups.io ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ? -- don??? va3drl |
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Re: Identify transformer
开云体育
Jim,
That list you attached came from my website. That is what is so confusing about this hunk of iron. Those colors don't match any standard.? ??
Walt Cates, WD0GOF
?
From: [email protected] <[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...>
Sent: Monday, December 2, 2024 2:48 PM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Identify transformer ?
All thing are possible since transformers are bilateral.? Typically, audio transformers do not use two black leads or two red leads for that matter and the laminations are usually thinner then those for AC power transformers.
OUTPUT TRANSFORMERS ARRL Radio Amateur's Handbook:?
Single-ended transformers:?
Plate lead (pri.) -------------- blue (or brown)?
B+ (power supply) lead --------- red?
speaker (typ. +) (sec.) -------- green (or yellow)?
speaker return (sec.) ---------- black?
I found the above info on the web, don't know who wrote it.? The full file is attached.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Monday, December 2, 2024 at 08:36:36 AM CST, waltcates via groups.io <cateswa@...> wrote:
Flip the drawing and you could have a push pull amp driving another stage.
Walt Cates,
WD0GOF
?
A majority of acceptance is not proof of correctness.
From: [email protected] <[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...>
Sent: Monday, December 2, 2024 3:15 AM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Identify transformer ?
Don
With a primary resistance of 85 ohms @ 12 Henrys and a secondary resistance of 0.6 ohms @ 0.055 Henrys how could this possibly be a step-up power transformer?? At 7 pounds, I would guess it would have a rating of perhaps 150 V-A.? So if the full
secondary is around 24 volts, the current would be around 6 amps.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Sunday, December 1, 2024 at 08:07:04 PM CST, don Root <drootofallevil@...> wrote:
Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ?
From: [email protected] [mailto:[email protected]]
On Behalf Of waltcates via groups.io ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ? -- don??? va3drl |
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Re: Identify transformer
All thing are possible since transformers are bilateral.? Typically, audio transformers do not use two black leads or two red leads for that matter and the laminations are usually thinner then those for AC power transformers. OUTPUT TRANSFORMERS
ARRL Radio Amateur's Handbook:? Single-ended transformers:? Plate lead (pri.) -------------- blue (or brown)? B+ (power supply) lead --------- red? speaker (typ. +) (sec.) -------- green (or yellow)? speaker return (sec.) ---------- black? I found the above info on the web, don't know who wrote it.? The full file is attached. Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Monday, December 2, 2024 at 08:36:36 AM CST, waltcates via groups.io <cateswa@...> wrote:
Flip the drawing and you could have a push pull amp driving another stage.
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.
From: [email protected] <[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...>
Sent: Monday, December 2, 2024 3:15 AM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Identify transformer ?
Don
With a primary resistance of 85 ohms @ 12 Henrys and a secondary resistance of 0.6 ohms @ 0.055 Henrys how could this possibly be a step-up power transformer?? At 7 pounds, I would guess it would have a rating of perhaps 150
V-A.? So if the full secondary is around 24 volts, the current would be around 6 amps.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Sunday, December 1, 2024 at 08:07:04 PM CST, don Root <drootofallevil@...> wrote:
Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ? From: [email protected] [mailto:[email protected]]
On Behalf Of waltcates via groups.io ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ? -- don??? va3drl |
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Re: Taming a VFO - HT46
开云体育
The big offenders in the 46 VFO are C84 10pf N750, C85 82pf N80, C86 100pf NPO, C87 47pf NPO and C89 82pf NPO. These 5 capacitors are all 20 years past their useful life. I would replace all 5. You can start looking at Surplus Sales of Nebraska.
Once you get the VFO calmed down you may want to download a modernized alignment procedure at:
Good luck with project.
Walt Cates, WD0GOF
?
From: [email protected] <[email protected]> on behalf of W0PWE via groups.io <j.b.hall@...>
Sent: Monday, December 2, 2024 12:17 PM To: [email protected] <[email protected]> Subject: [HallicraftersRadios] Taming a VFO - HT46 ?
The VFO in my newest HT46 has excessive drift. In standby mode it will drift about 1KHz in the first 15 minutes and then go another 600Hz in the following hour. The VFO drifts downward in frequency so it appears as though the capacitance in the tuned circuit needs more NEGATIVE temperature coefficient. It has a 10pfN750 and an 82pfN80 capacitor for compensation but they aren’t quite doing the job. ? Following some work by W7ZOI I have experimented with some different series combinations of N750 and NP0 capacitors in place of the 10pfN750. I have reduced the drift to about 10Hz/C but the series combination that produced that adds too much total capacitance to the circuit so it is not a solution. Experimental results and a few calculations would indicate I need a 10pfN1285 capacitor but of course that will be difficult to achieve. ? What bothers me about all this is that I have two other VFOs of this design - one in an SX146 receiver and the other in an old beat up and abused HT46. Both those VFOs have negligible drift. I have checked and re-checked the components in the offending VFO and I have compared them to what is in the well behaved HT46. Hopefully someone has experience with this or knows about a common cause for such behavior. 73 – Jerry – W0PWE ? |
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Re: Identify transformer
开云体育
Flip the drawing and you could have a push pull amp driving another stage.
Walt Cates, WD0GOF
?
From: [email protected] <[email protected]> on behalf of Jim Whartenby via groups.io <old_radio@...>
Sent: Monday, December 2, 2024 3:15 AM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Identify transformer ?
Don
With a primary resistance of 85 ohms @ 12 Henrys and a secondary resistance of 0.6 ohms @ 0.055 Henrys how could this possibly be a step-up power transformer?? At 7 pounds, I would guess it would have a rating of perhaps 150
V-A.? So if the full secondary is around 24 volts, the current would be around 6 amps.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Sunday, December 1, 2024 at 08:07:04 PM CST, don Root <drootofallevil@...> wrote:
Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ? From: [email protected] [mailto:[email protected]]
On Behalf Of waltcates via groups.io ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ? -- don??? va3drl |
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Re: Identify transformer
开云体育Thanks Jim, I must be visually wonky. That is bad. I know I should write the numbers down and compare apples with apples, but… ??a real goof here. Yes it must be a real step-down. 150 VA seems reasonable. ? From: [email protected] [mailto:[email protected]] On Behalf Of Jim Whartenby via groups.io
Sent: Monday, December 2, 2024 3:16 AM To: [email protected] Subject: Re: [HallicraftersRadios] Identify transformer ? Don With a primary resistance of 85 ohms @ 12 Henrys and a secondary resistance of 0.6 ohms @ 0.055 Henrys how could this possibly be a step-up power transformer?? At 7 pounds, I would guess it would have a rating of perhaps 150 V-A.? So if the full secondary is around 24 volts, the current would be around 6 amps. Jim ? ? Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy ? ? On Sunday, December 1, 2024 at 08:07:04 PM CST, don Root <drootofallevil@...> wrote: ? ? Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ? From: [email protected] [mailto:[email protected]] On Behalf Of waltcates via groups.io ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ?
? -- don??? va3drl |
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Re: Identify transformer
Don With a primary resistance of 85 ohms @ 12 Henrys and a secondary resistance of 0.6 ohms @ 0.055 Henrys how could this possibly be a step-up power transformer?? At 7 pounds, I would guess it would have a rating of perhaps 150 V-A.? So if the full secondary is around 24 volts, the current would be around 6 amps. Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Sunday, December 1, 2024 at 08:07:04 PM CST, don Root <drootofallevil@...> wrote:
Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ? From: [email protected] [mailto:[email protected]] On Behalf Of waltcates via groups.io
Sent: Sunday, December 1, 2024 6:35 PM To: [email protected] Subject: Re: [HallicraftersRadios] Identify transformer ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ? -- don??? va3drl |
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Re: Identify transformer
开云体育
I am not really interested?in further characteristics?of the transformer or building anything with it. I would like to know what radio it was used in so?I can make it available to someone who needs?it.
Walt Cates, WD0GOF
?
From: [email protected] <[email protected]> on behalf of don Root <drootofallevil@...>
Sent: Sunday, December 1, 2024 9:06 PM To: [email protected] <[email protected]> Subject: Re: [HallicraftersRadios] Identify transformer ?
Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ? From: [email protected] [mailto:[email protected]]
On Behalf Of waltcates via groups.io ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ? -- don??? va3drl |
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Re: Identify transformer
开云体育Yes Walt ? I consider the turns ratio to be a primary characteristic of any transformer, but voltage ratio is usually much the same.. assuming I was guessing that you just measured it and have it on the bench. Halli seems to like? “52….” for a power transformer ???so that might be a clue , but it has no filament windings so ?? ?From the ?impedance ratios , it is likely a step up , ? ?Have a look at the saturation knee to see if it fits 120vac? ? From: [email protected] [mailto:[email protected]] On Behalf Of waltcates via groups.io
Sent: Sunday, December 1, 2024 6:35 PM To: [email protected] Subject: Re: [HallicraftersRadios] Identify transformer ? Don,? did the photos come through on the original message. If they did, all the information I have is there. ? ? -- don??? va3drl |
Jacques_VE2JFE
waltcates
don Root
Jim Whartenby