Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
I'm in Steve, as often as I can mid April thru late Nov. but for occasional travel to ON and AB, or whatever...like most retirees.? Working on a winter remote....but not with Drake radios.
As such, not suitable as net control - sorry.
73 Peter VE7PS
On Wed, Mar 22, 2023 at 10:42?AM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: So, out of the gang here, how many of you would probably check-in to a 20m net on the weekends?? Let's see if this is worth pursuing.? I can certainly help out here, as I'm definitely on 20 with a decent signal (I can pick an L7 or a 30L-1).
73,
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent with Proton Mail secure email.
------- Original Message -------
On Wednesday, March 22nd, 2023 at 1:15 PM, Lyndon Nerenberg (VE7TFX/VE6BBM) <lyndon@...> wrote:
> I would be game to try 20m, although I don't know if my 2nd-floor-balcony
> doublet will put out any sort of signal on that band. I'll have a better
> idea later this week when I finish stringing it up and wire it in to the
> tuner.
>
> --lyndon
>
>
>
|
Re: R4C power supply question
Hi Steve,
?
I used the Sartori ¡°sold tubes¡± in the 3rd mixer position for a while until he went out of production.? Then I designed my MIX-4 replacement.? There
were two versions with different mixer components (40673 & later the SA602).?
?
Before I figured out how RFI hash was getting into the 3rd mixer I used a 1:1 120 volt shielded isolation transformer to keep the hash from getting
to the receiver.
?
Rob, NC0B
?
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Show quoted text
From: [email protected] [mailto:[email protected]]
On Behalf Of Steve Wedge, W1ES/4 via groups.io
Sent: Wednesday, March 22, 2023 11:58 AM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
I definitely noticed the hash on the audio when I bought my first later-production R-4C and spent a fair amount of time trying to tame it.? The location of that third mixer
and its design meant that very small differences in shield locations, variations in individual 6EJ7 tubes, etc., were critical to how well the 3rd mixer worked.? I was lucky in that doing the Sartori circuit tamed it enough that I could ignore whatever artefacts
were still there.? The early R-4C, with the 6HS6 mixers, didn't have this issue at all.? I agree that the performance of that mixer really threw a wet blanket on the whole experience but I did keep that C Line for a few years and even did some contesting with
it.? By that time, we were starting to hear the siren song of the Kenwood TS-930S and I made the switch in the late 80s.
I have since discovered that one can cherrypick 6EJ7's from a bunch of NOS tubes and get one that reduces the hash almost enough to not need to change any circuitry.
I still love the sharpness of the R-4C filters and have a C Line that works pretty well, stone-stock.
Time flies like an arrow.? Fruit flies like a banana.
------- Original Message -------
On Wednesday, March 22nd, 2023 at 12:59 PM, Rob Sherwood <rob@...> wrote:
Hi Doug,
?
Please see comments inserted below.
?
Rob, NC0B
?
From: [email protected] [mailto:[email protected]]
On Behalf Of Doug Crompton WA3DSP
Sent: Tuesday, March 21, 2023 11:28 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
Rob,
Yes I completely rebuilt the supply adding a 7812 regulator board which are dirt cheap on Amazon and elsewhere. I also added an LM380 audio board. again, dirt cheap, and everything runs from regulated 12V. I use 3 diodes in series to lower the low voltage to
the 7812 to about 14.5-15 volts and the 7812 loafs along.
?
Reply:? I never used your diode idea, and at least the way I used a copper strap from the 7812 to the chassis, 17 volts into the regulator was a non-issue.?
I used the LM-383T which puts out more power than the LM-380, but 100mW produces plenty of audio with a typical high efficiency speaker. I also used the LM-383T in my SE-3 AM sync detector, but running on 18 volts instead of 12 volts.
My R4C never had the C201 as far as I remember although I ripped quite a bit off the power supply board. There is no heat there anymore. I do have some very low level hum that is coming from somewhere ahead of the volume pot. It is absolutely clean with the
pot disconnected. It is very low level, but being a purist, I was looking for possible fixes.
?
Reply:? My engineer carefully specified how my LM-383T audio amp board had to have a single ground return. Otherwise there would be a ground-loop hum problem.?
That is likely what you are observing.?
I wonder if others have measured filament voltage. I used several digital meters and they all agreed that the filaments were running at about 7.0-7.1 volts. This is with a 121 volt line. I figured I needed about .3 ohms to lower it so I wound about 6 feet of
#30 enameled wire on a high value 2W resistor which dropped it about .5 volts or so.
Reply:? Yes the typical filament voltage is slightly higher than +10% above nominal 6.3 volts on
most of the hundreds of R-4Cs that came through my shop.? I recently was dealing with an R-4C that took 5 minutes to warm up, and the filament voltage was 6.1 volts.? I never came up with a solution to the slow warmup.? I never found tube life a problem with
the elevated filament voltage.?
I was also wondering when the LM380 first came out. The earliest data I can find is an app note dated 1972, so it had to be early in the R4C production, My R4C is SN 28387 which is very close to the end of production in 1976 or later so it certainly could have
had a much better power supply and audio amp at that late date.? Think of the space that would have been saved as most of the powers supply and audio boards would have gone away, I guess by 1976 they were working on the TR7 design which used the newer chips.
?
Reply:? Drake is notorious for using big dropping resistors in products.? Look at the L-4B power supply and all the heat in those large resistors.? The
TR-7 wasn¡¯t any better with all the heat in regulators sinked to the chassis near the PTO.? Also why put the 100 watt PA right by the PTO??? Why put the R-4C power transformer right behind the PTO?? The earlier Drake R-4, R-4A and R-4B receivers had the power
transformer oriented 90 degrees from where it is in the R-4C.? In the R-4C case, the transformer magnetic field couples into the PTO slug-tuned inductor causing hum sidebands on the PTO output. If you operate the PTO outside the radio it has no line-related
sidebands.? If you remove the R-4C power transformer, punch two new holes in the chassis, and remount the transformer 90 degrees from normal (as it is in earlier models), the line-related hum sidebands on the PTO signal are drastically lower.? Please see attached
PDF from my 2012 Drake Dayton Forum presentation.
?
COMMENTS:? Consider the parts count in the TR-7 DR-7 board with all those TTL chips.? The parts count on that board, and likely many others, could have
been drastically reduced, decreasing assembly time and cost.? The change in the R-4C from 6HS6 mixer tubes to 6EJ7s, and the subsequent circuit change for LO injection, was a terrible step backwards.? Any RFI noise on the AC line passed right into the grid
of the 3rd mixer.? That didn¡¯t happen with the 6HS6 circuit. ?Drake did well for decades in spite of design errors and the lack of production updates that would have saved money and made the products better. I wonder if the culture at Drake had
been more proactive whether the TR-8 would? have had a chance in the market?? David Assaf W5XU is the TR-8 guru, but I don¡¯t know whether a schematic even exists for the TR-8. ?Was it designed well?? I? have no idea. ?????
?
73, Rob, NC0B
Doug, WA3DSP
?
|
Re: R4C power supply question
Hi Doug,
?
I tried mu metal shielding but to no avail.? Yes rotating the transformer is tedious, but it solves the problem.? There is quite a variation from R-4C to R-4C
and I have? no idea why.? That said they are all bad from my perspective, just some worse than others.
?
Rob, NC0B
?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]]
On Behalf Of Doug Crompton WA3DSP
Sent: Wednesday, March 22, 2023 11:50 AM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
I would first have to determine if this is actually a problem in my R4C but I doubt I would go to the trouble of reorienting the transformer. I have a large piece of mumetal somewhere that we used in our magnetic disk test equipment. It
would be interesting to see if a piece of that between the transformer and the PTO would help.
Doug, WA3DSP
|
Re: R4C power supply question
Hi Paul,
Comments inserted below.
Ro
?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]]
On Behalf Of Paul Christensen
Sent: Wednesday, March 22, 2023 11:27 AM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
Rob,
?
I don¡¯t recall if you and I reached the same but independent conclusions at the same time, but I discovered the power transformer issue back in 2011 when my R-4C and R-4B underwent
thorough upgrades.? However, the transformer fix only affected the R-4C.
?
Reply:? We must have arrived at the same conclusion and solution independently.? First I tried some mu metal shielding to no avail, and my R-4C was likely modified
sometime in 2011 before my 2012 Hamvention presentation. ?The hum sidebands, solder braid and grounding solder lug improvement were in my 2010 Drake Forum presentation with attribution where appropriate.? My original R-4, when I was in high school, needed
a better ground than provided by the PTO spring .? As a 16 or 17 ?year old I demonstrated the problem to Drake at the factory and was blown off as a ¡°snot nosed kid¡±.? Hi Hi? ??They replaced my PTO saying the newer production PTOs had harder ball bearings
that provided a better ground.? Drake never put the flexible grounding braid on the PTO into production until late TR-7s.? ?
?
?
Although the root cause is different, and as your slides show, it has the classic characteristics of so-called ¡°hum modulation,¡± essentially FM-like sidebands at 60 Hz intervals.?
I first noticed it on my R-4C when listening to the crystal calibrator up at 500 kHz on the top end of the PTO.? As the PTO is adjusted toward the 500 kHz end, the ferrite core moves closer to the power transformer.? That coupled with the wrong transformer
orientation creates this effect in the R-4C, sometimes even after separately grounding the PTO case.
?
Reply:? No question about that.
?
I think the reason this had gone unnoticed for decades is because the CW portion of the bands are at the other extreme of the PTO ferrite core position.? If the reverse were
true (i.e., CW portion at the high end of the bands), no doubt some folks would have picked up on this limitation much sooner.? Hum modulation effects are much more apparent when listening in CW mode than when listening to SSB transmissions although when bad
enough it makes voice sound ¡°fuzzy.¡±
?
Reply:? I agree, but I found the effect on ¡°fuzzy¡± SSB unacceptable, too.? I wasn¡¯t doing much CW in those days.?? ??
?
After the transformer mod, 60 Hz sidebands are diminished to the point of inaudibility.? It would probably be wrong for everyone to start modifying their R-4C receivers.?
?
Reply:? Yes likely too much trouble, but if an R-4C owner is a nitpicker like you and I the difference is very significant.
?
As a rule, I get deeply perturbed by the presence of any hum or buzz in receiver audio.? Shortly after working on the Drake receivers, I moved on to Collins 75S-3A and 75S-3C
C receivers and eliminated hum in those receivers but it took many hours of work.?
?
Reply:? I eventually owned an S Line and spent a few years ¡°fixing¡± some of its issues.? PDFs attached.?
?
On my bench at the moment is a Hallicrafters SR-400A ¡°Cyclone III¡± transceiver that will soon get the same treatment.
?
Comment:? I briefly owned a Squires Sanders SS-1R and modified it to cover 160 meters.? Unfortunately I sold it before I started testing receivers.? I have
always wondered how well it would? have performed from a noise floor and dynamic range standpoint.? See link to the receiver.? http://www.w1vd.com/SS-1R.html
?
73, Rob, NC0B
?
?
Paul, W9AC
?
?
tom: [email protected]
<[email protected]> On Behalf Of Rob Sherwood
Sent: Wednesday, March 22, 2023 1:00 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
Hi Doug,
?
Please see comments inserted below.
?
Rob, NC0B
?
From:
[email protected] [mailto:[email protected]]
On Behalf Of Doug Crompton WA3DSP
Sent: Tuesday, March 21, 2023 11:28 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
Rob,
Yes I completely rebuilt the supply adding a 7812 regulator board which are dirt cheap on Amazon and elsewhere. I also added an LM380 audio board. again, dirt cheap, and everything runs from regulated 12V. I use 3 diodes in series to lower the low voltage to
the 7812 to about 14.5-15 volts and the 7812 loafs along.
?
Reply:? I never used your diode idea, and at least the way I used a copper strap from the 7812 to the chassis, 17 volts into the regulator was a non-issue.? I used the LM-383T which puts out more power than the
LM-380, but 100mW produces plenty of audio with a typical high efficiency speaker. I also used the LM-383T in my SE-3 AM sync detector, but running on 18 volts instead of 12 volts.
My R4C never had the C201 as far as I remember although I ripped quite a bit off the power supply board. There is no heat there anymore. I do have some very low level hum that is coming from somewhere ahead of the volume pot. It is absolutely clean with the
pot disconnected. It is very low level, but being a purist, I was looking for possible fixes.
?
Reply:? My engineer carefully specified how my LM-383T audio amp board had to have a single ground return. Otherwise there would be a ground-loop hum problem.? That is likely what
you are observing.?
I wonder if others have measured filament voltage. I used several digital meters and they all agreed that the filaments were running at about 7.0-7.1 volts. This is with a 121 volt line. I figured I needed about .3 ohms to lower it so I wound about 6 feet of
#30 enameled wire on a high value 2W resistor which dropped it about .5 volts or so.
Reply:? Yes the typical filament voltage is slightly higher than +10% above nominal 6.3 volts on most of the hundreds of R-4Cs that came through my shop.? I
recently was dealing with an R-4C that took 5 minutes to warm up, and the filament voltage was 6.1 volts.? I never came up with a solution to the slow warmup.? I never found tube life a problem with the elevated filament voltage.?
I was also wondering when the LM380 first came out. The earliest data I can find is an app note dated 1972, so it had to be early in the R4C production, My R4C is SN 28387 which is very close to the end of production in 1976 or later so it certainly could have
had a much better power supply and audio amp at that late date.? Think of the space that would have been saved as most of the powers supply and audio boards would have gone away, I guess by 1976 they were working on the TR7 design which used the newer chips.
?
Reply:? Drake is notorious for using big dropping resistors in products.? Look at the L-4B power supply and all the heat in those large resistors.? The TR-7 wasn¡¯t any better with all the heat in regulators sinked
to the chassis near the PTO.? Also why put the 100 watt PA right by the PTO??? Why put the R-4C power transformer right behind the PTO?? The earlier Drake R-4, R-4A and R-4B receivers had the power transformer oriented 90 degrees from where it is in the R-4C.?
In the R-4C case, the transformer magnetic field couples into the PTO slug-tuned inductor causing hum sidebands on the PTO output. If you operate the PTO outside the radio it has no line-related sidebands.? If you remove the R-4C power transformer, punch two
new holes in the chassis, and remount the transformer 90 degrees from normal (as it is in earlier models), the line-related hum sidebands on the PTO signal are drastically lower.? Please see attached PDF from my 2012 Drake Dayton Forum presentation.
?
COMMENTS:? Consider the parts count in the TR-7 DR-7 board with all those TTL chips.? The parts count on that board, and likely many others, could have been drastically reduced, decreasing assembly time and cost.?
The change in the R-4C from 6HS6 mixer tubes to 6EJ7s, and the subsequent circuit change for LO injection, was a terrible step backwards.? Any RFI noise on the AC line passed right into the grid of the 3rd mixer.? That didn¡¯t happen with the 6HS6
circuit. ?Drake did well for decades in spite of design errors and the lack of production updates that would have saved money and made the products better. I wonder if the culture at Drake had been more proactive whether the TR-8 would? have had a chance in
the market?? David Assaf W5XU is the TR-8 guru, but I don¡¯t know whether a schematic even exists for the TR-8. ?Was it designed well?? I? have no idea. ?????
?
73, Rob, NC0B
Doug, WA3DSP
|
Re: R4C power supply question
I definitely noticed the hash on the audio when I bought my first later-production R-4C and spent a fair amount of time trying to tame it.? The location of that third mixer and its design meant that very small differences in shield locations, variations in individual 6EJ7 tubes, etc., were critical to how well the 3rd mixer worked.? I was lucky in that doing the Sartori circuit tamed it enough that I could ignore whatever artefacts were still there.? The early R-4C, with the 6HS6 mixers, didn't have this issue at all.? I agree that the performance of that mixer really threw a wet blanket on the whole experience but I did keep that C Line for a few years and even did some contesting with it.? By that time, we were starting to hear the siren song of the Kenwood TS-930S and I made the switch in the late 80s.
I have since discovered that one can cherrypick 6EJ7's from a bunch of NOS tubes and get one that reduces the hash almost enough to not need to change any circuitry.
I still love the sharpness of the R-4C filters and have a C Line that works pretty well, stone-stock.
73,
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
------- Original Message -------
On Wednesday, March 22nd, 2023 at 12:59 PM, Rob Sherwood <rob@...> wrote:
Hi Doug,
?
Please see comments inserted below.
?
Rob, NC0B
?
From: [email protected] [mailto:[email protected]]
On Behalf Of Doug Crompton WA3DSP
Sent: Tuesday, March 21, 2023 11:28 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
Rob,
Yes I completely rebuilt the supply adding a 7812 regulator board which are dirt cheap on Amazon and elsewhere. I also added an LM380 audio board. again, dirt cheap, and everything runs from regulated 12V. I use 3 diodes in series to lower the low voltage to
the 7812 to about 14.5-15 volts and the 7812 loafs along.
?
Reply:? I never used your diode idea, and at least the way I used a copper strap from the 7812 to the chassis, 17 volts into the regulator was a non-issue.? I used the LM-383T which puts out more power than the
LM-380, but 100mW produces plenty of audio with a typical high efficiency speaker. I also used the LM-383T in my SE-3 AM sync detector, but running on 18 volts instead of 12 volts.
My R4C never had the C201 as far as I remember although I ripped quite a bit off the power supply board. There is no heat there anymore. I do have some very low level hum that is coming from somewhere ahead of the volume pot. It is absolutely clean with the
pot disconnected. It is very low level, but being a purist, I was looking for possible fixes.
?
Reply:? My engineer carefully specified how my LM-383T audio amp board had to have a single ground return. Otherwise there would be a ground-loop hum problem.? That is likely what you are observing.?
I wonder if others have measured filament voltage. I used several digital meters and they all agreed that the filaments were running at about 7.0-7.1 volts. This is with a 121 volt line. I figured I needed about .3 ohms to lower it so I wound about 6 feet of
#30 enameled wire on a high value 2W resistor which dropped it about .5 volts or so.
Reply:? Yes the typical filament voltage is slightly higher than +10% above nominal 6.3 volts on most of the hundreds of R-4Cs that came through my shop.? I
recently was dealing with an R-4C that took 5 minutes to warm up, and the filament voltage was 6.1 volts.? I never came up with a solution to the slow warmup.? I never found tube life a problem with the elevated filament voltage.?
I was also wondering when the LM380 first came out. The earliest data I can find is an app note dated 1972, so it had to be early in the R4C production, My R4C is SN 28387 which is very close to the end of production in 1976 or later so it certainly could have
had a much better power supply and audio amp at that late date.? Think of the space that would have been saved as most of the powers supply and audio boards would have gone away, I guess by 1976 they were working on the TR7 design which used the newer chips.
?
Reply:? Drake is notorious for using big dropping resistors in products.? Look at the L-4B power supply and all the heat in those large resistors.? The TR-7 wasn¡¯t any better with all the heat in regulators sinked
to the chassis near the PTO.? Also why put the 100 watt PA right by the PTO??? Why put the R-4C power transformer right behind the PTO?? The earlier Drake R-4, R-4A and R-4B receivers had the power transformer oriented 90 degrees from where it is in the R-4C.?
In the R-4C case, the transformer magnetic field couples into the PTO slug-tuned inductor causing hum sidebands on the PTO output. If you operate the PTO outside the radio it has no line-related sidebands.? If you remove the R-4C power transformer, punch two
new holes in the chassis, and remount the transformer 90 degrees from normal (as it is in earlier models), the line-related hum sidebands on the PTO signal are drastically lower.? Please see attached PDF from my 2012 Drake Dayton Forum presentation.
?
COMMENTS:? Consider the parts count in the TR-7 DR-7 board with all those TTL chips.? The parts count on that board, and likely many others, could have been drastically reduced, decreasing assembly time and cost.?
The change in the R-4C from 6HS6 mixer tubes to 6EJ7s, and the subsequent circuit change for LO injection, was a terrible step backwards.? Any RFI noise on the AC line passed right into the grid of the 3rd mixer.? That didn¡¯t happen with the 6HS6
circuit. ?Drake did well for decades in spite of design errors and the lack of production updates that would have saved money and made the products better. I wonder if the culture at Drake had been more proactive whether the TR-8 would? have had a chance in
the market?? David Assaf W5XU is the TR-8 guru, but I don¡¯t know whether a schematic even exists for the TR-8. ?Was it designed well?? I? have no idea. ?????
?
73, Rob, NC0B
Doug, WA3DSP
|
Re: R4C power supply question
I would first have to determine if this is actually a problem in my R4C but I doubt I would go to the trouble of reorienting the transformer. I have a large piece of mumetal somewhere that we used in our magnetic disk test equipment. It would be interesting to see if a piece of that between the transformer and the PTO would help.
Doug, WA3DSP
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
So, out of the gang here, how many of you would probably check-in to a 20m net on the weekends? Let's see if this is worth pursuing. I can certainly help out here, as I'm definitely on 20 with a decent signal (I can pick an L7 or a 30L-1).
73,
Steve Wedge, W1ES/4
Time flies like an arrow.? Fruit flies like a banana.
Sent with Proton Mail secure email.
toggle quoted message
Show quoted text
------- Original Message ------- On Wednesday, March 22nd, 2023 at 1:15 PM, Lyndon Nerenberg (VE7TFX/VE6BBM) <lyndon@...> wrote: I would be game to try 20m, although I don't know if my 2nd-floor-balcony
doublet will put out any sort of signal on that band. I'll have a better
idea later this week when I finish stringing it up and wire it in to the
tuner.
--lyndon
|
Re: R4C power supply question
Rob, ? I don¡¯t recall if you and I reached the same but independent conclusions at the same time, but I discovered the power transformer issue back in 2011 when my R-4C and R-4B underwent thorough upgrades.? However, the transformer fix only affected the R-4C.? ? Although the root cause is different, and as your slides show, it has the classic characteristics of so-called ¡°hum modulation,¡± essentially FM-like sidebands at 60 Hz intervals.? I first noticed it on my R-4C when listening to the crystal calibrator up at 500 kHz on the top end of the PTO.? As the PTO is adjusted toward the 500 kHz end, the ferrite core moves closer to the power transformer.? That coupled with the wrong transformer orientation creates this effect in the R-4C, sometimes even after separately grounding the PTO case. ? I think the reason this had gone unnoticed for decades is because the CW portion of the bands are at the other extreme of the PTO ferrite core position.? If the reverse were true (i.e., CW portion at the high end of the bands), no doubt some folks would have picked up on this limitation much sooner.? Hum modulation effects are much more apparent when listening in CW mode than when listening to SSB transmissions although when bad enough it makes voice sound ¡°fuzzy.¡± ? After the transformer mod, 60 Hz sidebands are diminished to the point of inaudibility.? It would probably be wrong for everyone to start modifying their R-4C receivers.? As a rule, I get deeply perturbed by the presence of any hum or buzz in receiver audio.? Shortly after working on the Drake receivers, I moved on to Collins 75S-3A and 75S-3C C receivers and eliminated hum in those receivers but it took many hours of work.? On my bench at the moment is a Hallicrafters SR-400A ¡°Cyclone III¡± transceiver that will soon get the same treatment. ? Paul, W9AC ? ? tom: [email protected] <[email protected]> On Behalf Of Rob Sherwood
Sent: Wednesday, March 22, 2023 1:00 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question ? Hi Doug, ? Please see comments inserted below. ? Rob, NC0B ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Doug Crompton WA3DSP
Sent: Tuesday, March 21, 2023 11:28 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question ? Rob,
Yes I completely rebuilt the supply adding a 7812 regulator board which are dirt cheap on Amazon and elsewhere. I also added an LM380 audio board. again, dirt cheap, and everything runs from regulated 12V. I use 3 diodes in series to lower the low voltage to the 7812 to about 14.5-15 volts and the 7812 loafs along. ? Reply:? I never used your diode idea, and at least the way I used a copper strap from the 7812 to the chassis, 17 volts into the regulator was a non-issue.? I used the LM-383T which puts out more power than the LM-380, but 100mW produces plenty of audio with a typical high efficiency speaker. I also used the LM-383T in my SE-3 AM sync detector, but running on 18 volts instead of 12 volts.
My R4C never had the C201 as far as I remember although I ripped quite a bit off the power supply board. There is no heat there anymore. I do have some very low level hum that is coming from somewhere ahead of the volume pot. It is absolutely clean with the pot disconnected. It is very low level, but being a purist, I was looking for possible fixes. ? Reply:? My engineer carefully specified how my LM-383T audio amp board had to have a single ground return. Otherwise there would be a ground-loop hum problem.? That is likely what you are observing.?
I wonder if others have measured filament voltage. I used several digital meters and they all agreed that the filaments were running at about 7.0-7.1 volts. This is with a 121 volt line. I figured I needed about .3 ohms to lower it so I wound about 6 feet of #30 enameled wire on a high value 2W resistor which dropped it about .5 volts or so. Reply:? Yes the typical filament voltage is slightly higher than +10% above nominal 6.3 volts on most of the hundreds of R-4Cs that came through my shop.? I recently was dealing with an R-4C that took 5 minutes to warm up, and the filament voltage was 6.1 volts.? I never came up with a solution to the slow warmup.? I never found tube life a problem with the elevated filament voltage.?
I was also wondering when the LM380 first came out. The earliest data I can find is an app note dated 1972, so it had to be early in the R4C production, My R4C is SN 28387 which is very close to the end of production in 1976 or later so it certainly could have had a much better power supply and audio amp at that late date.? Think of the space that would have been saved as most of the powers supply and audio boards would have gone away, I guess by 1976 they were working on the TR7 design which used the newer chips.
? Reply:? Drake is notorious for using big dropping resistors in products.? Look at the L-4B power supply and all the heat in those large resistors.? The TR-7 wasn¡¯t any better with all the heat in regulators sinked to the chassis near the PTO.? Also why put the 100 watt PA right by the PTO??? Why put the R-4C power transformer right behind the PTO?? The earlier Drake R-4, R-4A and R-4B receivers had the power transformer oriented 90 degrees from where it is in the R-4C.? In the R-4C case, the transformer magnetic field couples into the PTO slug-tuned inductor causing hum sidebands on the PTO output. If you operate the PTO outside the radio it has no line-related sidebands.? If you remove the R-4C power transformer, punch two new holes in the chassis, and remount the transformer 90 degrees from normal (as it is in earlier models), the line-related hum sidebands on the PTO signal are drastically lower.? Please see attached PDF from my 2012 Drake Dayton Forum presentation. ? COMMENTS:? Consider the parts count in the TR-7 DR-7 board with all those TTL chips.? The parts count on that board, and likely many others, could have been drastically reduced, decreasing assembly time and cost.? The change in the R-4C from 6HS6 mixer tubes to 6EJ7s, and the subsequent circuit change for LO injection, was a terrible step backwards.? Any RFI noise on the AC line passed right into the grid of the 3rd mixer.? That didn¡¯t happen with the 6HS6 circuit. ?Drake did well for decades in spite of design errors and the lack of production updates that would have saved money and made the products better. I wonder if the culture at Drake had been more proactive whether the TR-8 would? have had a chance in the market?? David Assaf W5XU is the TR-8 guru, but I don¡¯t know whether a schematic even exists for the TR-8. ?Was it designed well?? I? have no idea. ????? ? 73, Rob, NC0B
Doug, WA3DSP
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
Lyndon Nerenberg (VE7TFX/VE6BBM)
I would be game to try 20m, although I don't know if my 2nd-floor-balcony
doublet will put out any sort of signal on that band. I'll have a better
idea later this week when I finish stringing it up and wire it in to the
tuner.
--lyndon
|
Re: R4C power supply question
Hi Doug,
?
Please see comments inserted below.
?
Rob, NC0B
?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]]
On Behalf Of Doug Crompton WA3DSP
Sent: Tuesday, March 21, 2023 11:28 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C power supply question
?
Rob,
Yes I completely rebuilt the supply adding a 7812 regulator board which are dirt cheap on Amazon and elsewhere. I also added an LM380 audio board. again, dirt cheap, and everything runs from regulated 12V. I use 3 diodes in series to lower the low voltage to
the 7812 to about 14.5-15 volts and the 7812 loafs along.
?
Reply:? I never used your diode idea, and at least the way I used a copper strap from the 7812 to the chassis, 17 volts into the regulator was a non-issue.? I used the LM-383T which puts out more power than the
LM-380, but 100mW produces plenty of audio with a typical high efficiency speaker. I also used the LM-383T in my SE-3 AM sync detector, but running on 18 volts instead of 12 volts.
My R4C never had the C201 as far as I remember although I ripped quite a bit off the power supply board. There is no heat there anymore. I do have some very low level hum that is coming from somewhere ahead of the volume pot. It is absolutely clean with the
pot disconnected. It is very low level, but being a purist, I was looking for possible fixes.
?
Reply:? My engineer carefully specified how my LM-383T audio amp board had to have a single ground return. Otherwise there would be a ground-loop hum problem.? That is likely what you are observing.?
I wonder if others have measured filament voltage. I used several digital meters and they all agreed that the filaments were running at about 7.0-7.1 volts. This is with a 121 volt line. I figured I needed about .3 ohms to lower it so I wound about 6 feet of
#30 enameled wire on a high value 2W resistor which dropped it about .5 volts or so.
Reply:? Yes the typical filament voltage is slightly higher than +10% above nominal 6.3 volts on most of the hundreds of R-4Cs that came through my shop.? I
recently was dealing with an R-4C that took 5 minutes to warm up, and the filament voltage was 6.1 volts.? I never came up with a solution to the slow warmup.? I never found tube life a problem with the elevated filament voltage.?
I was also wondering when the LM380 first came out. The earliest data I can find is an app note dated 1972, so it had to be early in the R4C production, My R4C is SN 28387 which is very close to the end of production in 1976 or later so it certainly could have
had a much better power supply and audio amp at that late date.? Think of the space that would have been saved as most of the powers supply and audio boards would have gone away, I guess by 1976 they were working on the TR7 design which used the newer chips.
?
Reply:? Drake is notorious for using big dropping resistors in products.? Look at the L-4B power supply and all the heat in those large resistors.? The TR-7 wasn¡¯t any better with all the heat in regulators sinked
to the chassis near the PTO.? Also why put the 100 watt PA right by the PTO??? Why put the R-4C power transformer right behind the PTO?? The earlier Drake R-4, R-4A and R-4B receivers had the power transformer oriented 90 degrees from where it is in the R-4C.?
In the R-4C case, the transformer magnetic field couples into the PTO slug-tuned inductor causing hum sidebands on the PTO output. If you operate the PTO outside the radio it has no line-related sidebands.? If you remove the R-4C power transformer, punch two
new holes in the chassis, and remount the transformer 90 degrees from normal (as it is in earlier models), the line-related hum sidebands on the PTO signal are drastically lower.? Please see attached PDF from my 2012 Drake Dayton Forum presentation.
?
COMMENTS:? Consider the parts count in the TR-7 DR-7 board with all those TTL chips.? The parts count on that board, and likely many others, could have been drastically reduced, decreasing assembly time and cost.?
The change in the R-4C from 6HS6 mixer tubes to 6EJ7s, and the subsequent circuit change for LO injection, was a terrible step backwards.? Any RFI noise on the AC line passed right into the grid of the 3rd mixer.? That didn¡¯t happen with the 6HS6
circuit. ?Drake did well for decades in spite of design errors and the lack of production updates that would have saved money and made the products better. I wonder if the culture at Drake had been more proactive whether the TR-8 would? have had a chance in
the market?? David Assaf W5XU is the TR-8 guru, but I don¡¯t know whether a schematic even exists for the TR-8. ?Was it designed well?? I? have no idea. ?????
?
73, Rob, NC0B
Doug, WA3DSP
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
Collins at 2:00 utc. 14.263
Elkins Wetherill
Senior Vice President / Regional Partner
Verus Partners, LLC
ewetherill@...
484-433-0709
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Show quoted text
On Mar 22, 2023, at 10:34 AM, Mark - WB0IQK via groups.io <mgilger@...> wrote:
?There are 3 vintage nets held on 14.292.5 every Sunday.? If someone wanted to start a Drake net how about either 2pm or 6pm eastern? Would have to coordinate with the NCS's of those nets to let them know as they sometimes tend to run over their
hour time slot.?
3pm Eastern = Vintage SSB net
4pm Eastern = Heathkit net
5pm Eastern = Swan net
73's,
Mark, WB0IQK
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
Mark,
I think you are off by an hour.
The vintage SSB net is 2pm to 3pm ET Heathkit net 3pm to 4pm ET Swan net 4pm to 5pm ET
Don¡¯t forget the Collins net on 14.263 at 4pm ET
Plus your Kenwood net at 2pm ET
73,
toggle quoted message
Show quoted text
On Mar 22, 2023, at 10:34 AM, Mark - WB0IQK <mgilger@...> wrote:
?There are 3 vintage nets held on 14.292.5 every Sunday.? If someone wanted to start a Drake net how about either 2pm or 6pm eastern? Would have to coordinate with the NCS's of those nets to let them know as they sometimes tend to run over their hour time slot.?
3pm Eastern = Vintage SSB net
4pm Eastern = Heathkit net
5pm Eastern = Swan net
73's,
Mark, WB0IQK
|
Drake service CDs no longer available from K4OAH?
I attempted to order a CD using PayPal. I got a message back from PayPal saying that recipient needed to open a PayPal account and if they don't do that within 10 days the transaction will be cancelled. My email to K4OAH regarding this was not responded to and PayPal eventually cancelled the transaction.
--
Bill N0CU
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
The Collins Collectors Association original?20m net is on or about 14.263 at 2000 UTC on Sunday afternoon. It gets cancelled on major contest weekends via the CCA email list.? I can usually get into this one if I try.
The?CCA? has a plethora of other nets on 80m including?an AM net on the 1st Wednesday of each month.? See here:
This one worked well for me when I lived in VE3, but the western one is out of California and doesn't work so well from southern?BC.
The Kenwood Hybrid nets are as follows; Saturday on 7.242 mhz at 3:30 pm EST/EDT. Sunday on 14.316 Mhz at 1800 UTC.
I have checked into the Sunday one on 20m, run by Mark, WB0IQK, with some help from others.? Seems lots of mid-USA and west coasters manage to check in OK, but it helps if you have a beam and 500w+.? I use one of the 30L-1's typically with the Kenwoods and that seems to work. It can get crowded at times on .316 but a regular group gathers for the hour prior to the Sunday net and politely "saves them a spot"!
I rarely ever hear the 40m nets from the east.? A 40m vertical doesn't cut it, and I'm away too much in the winter anyways when it?is a possibility.? Summer is a write-off from BC at that time and distance.
I used to occasionally check into the Drake group out of California - Friday nights I think?? Not really a net....that also does a real-time online video at the same time.? I don't recall the platform they used.? It worked pretty well....but again Fridays tend to be busy days for me into the evening.? I have not checked in for several years now.? Somebody here would likely know more about that one.
I see Mark has just listed the "vintage nets" which are not manufacturer specific.
73 Peter VE7PS
On Wed, Mar 22, 2023 at 5:58?AM Steve Wedge, W1ES/4 via <w1es= [email protected]> wrote: Why not get some volunteers to start it up on 20?? All we need are a few people willing to take turns being NCS. The harder part will be to find the right time and frequency, since there are likely other regular nets around, and to not schedule it at the same time as other interest group nets that are similar. It would take some coordination and the net itself would likely start slowly.?
For precedent, there are Collins and Kenwood nets on 20, I believe. I am of the opinion that there are many more people interested in Drakes than what existed even a few years ago.?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent from Proton Mail for iOS
On Tue, Mar 21, 2023 at 4:15 PM, Mark - WB0IQK < mgilger@...> wrote: We tried a 20 meter net many years ago and it never worked out. Very limited check-ins.? We also had a 75m swap net and had to disband that some years ago due to lack of participation.?
73's,
Mark, WB0IQK?
|
Re: Rob, Question re your "Custom Front Panel Switch" mod
I tried a 1.0 uF ceramic (because that is all I have on hand) in series with a 33K resistor. I placed this network in parallel with the M RC network and got the desired result with no obvious problems noted. I'll order a Mylar cap next time I go to Digikey. Thanks
On Tue, Mar 21, 2023 at 12:36?PM Richard Knoppow < 1oldlens1@...> wrote: The performance of ceramic caps depends on the exact type of material.? npo type are very good ,? it is the "hi k" type that have problems.? Temperature compensating caps have charities similar to NPO.? The best performance overall is polypropylene.? Look up polypropylene and mylar to see the differences.? Old tubular caps are not all paper but most are. Plastic film caps are in all ways superior.
-------- Original message -------- Date: 3/21/23 10:21 AM (GMT-08:00) Subject: Re: [DRAKE-RADIO] Rob, Question re your "Custom Front Panel Switch" mod
Ceramic capacitors are bottom rung devices, with differing temperature coefficients depending on type (NPO being the best for routine cooling and bypassing applications). They do not fare well at low frequencies and they can be quite noisy, even somewhat microphonic.They are generally not used in signal path applications.
The tubular ones to which you refer are, at this radio¡¯s vintage, paper capacitors. They are non-polarized except for the fact that the outermost metallization is typically tied to ground to reduce noise pickup and to ensure that the outermost layer is at ground potential. That is why these types often (not always) have a band on one end to indicate which end should be grounded.
To replace these capacitors, the best choice would be modern Mylar capacitors, readily available for DigiKey or Mouser. I always buy 630 volt devices so I only need to stock one drawer of each value. There is no downside to using higher than needed voltage rated parts, other than size. However, the modern parts are so much smaller than the originals that this is not an issue.
The biggest issue with modern parts is that the leads are often not long enough to reach the tie points in older radios (particularly in Collins radios). That won¡¯t be a problem generally with Drake radios though.
Gary
W0DVN
I don't see any mention as to what type of capacitors to use. The reason I ask is I don't know why Drake used large tubular capacitors in their design. Is there any reason ceramic capacitors can't be used?
--
Bill N0CU
|
Re: R4C power supply question
Doug,
By the looks of it, production ended in 1979.??
The last one that Ron has listed is 29306, so there are probably some higher than that, but not many I suspect.?
73's,
Mark, WB0IQK
|
Re: R4C power supply question
Doug, I had the same issue with the filament voltages on my R4-C. I coiled up (I am guessing about 6 ft) of small gauge hookup wire and trimmed it to get the correct voltage. The coil was about 1 1/2 diameter and I just laid it down next to the PS board. There are a number of sharp edges in that area and I felt better using insulated hookup wire instead of enameled wire.
On Tue, Mar 21, 2023 at 11:28?PM Doug Crompton WA3DSP < wa3dsp@...> wrote: Rob,
Yes I completely rebuilt the supply adding a 7812 regulator board which are dirt cheap on Amazon and elsewhere. I also added an LM380 audio board. again, dirt cheap, and everything runs from regulated 12V. I use 3 diodes in series to lower the low voltage to the 7812 to about 14.5-15 volts and the 7812 loafs along.
My R4C never had the C201 as far as I remember although I ripped quite a bit off the power supply board. There is no heat there anymore. I do have some very low level hum that is coming from somewhere ahead of the volume pot. It is absolutely clean with the pot disconnected. It is very low level, but being a purist, I was looking for possible fixes.
I wonder if others have measured filament voltage. I used several digital meters and they all agreed that the filaments were running at about 7.0-7.1 volts. This is with a 121 volt line. I figured I needed about .3 ohms to lower it so I wound about 6 feet of #30 enameled wire on a high value 2W resistor which dropped it about .5 volts or so.
I was also wondering when the LM380 first came out. The earliest data I can find is an app note dated 1972, so it had to be early in the R4C production, My R4C is SN 28387 which is very close to the end of production in 1976 or later so it certainly could have had a much better power supply and audio amp at that late date.? Think of the space that would have been saved as most of the powers supply and audio boards would have gone away, I guess by 1976 they were working on the TR7 design which used the newer chips.
Doug, WA3DSP
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
There are 3 vintage nets held on 14.292.5 every Sunday.? If someone wanted to start a Drake net how about either 2pm or 6pm eastern? Would have to coordinate with the NCS's of those nets to let them know as they sometimes tend to run over their hour time slot.?
3pm Eastern = Vintage SSB net
4pm Eastern = Heathkit net
5pm Eastern = Swan net
73's,
Mark, WB0IQK
|
I've never worked on a 2C, but did I read that the shaft (or bushing?) is made of a fibrous material? If so, will that absorb oil and expand?
Thanks,
Barry - N4BUQ
toggle quoted message
Show quoted text
----- Original Message ----- From: "Dave Edwards" <kd2e@...>
To: "DRAKE-RADIO" <[email protected]>
Cc: "Gary Follett" <xntrick1948@...>
Sent: Wednesday, March 22, 2023 6:51:25 AM
Subject: Re: [DRAKE-RADIO] 2-C Receiver I would first check really carefully...with a loupe or magnifying glass,
and a STRONG light to see if the existing knob is not already split perhaps.
As far as the control itself...I would avoid spray stuff.
I'd suggest a thin oil, with a toothpick. study the control carefully,
finding the bearing points. Drop one drop of oil wherever you see the
point where something supports the rotation (perhaps front and rear
bearing??)
Again, a strong lamp is key. Be nice to the 2C. It is an amazing, and
trailblazing rig!!
...Dave? KD2E
On 3/21/23 5:17 PM, Dave via groups.io wrote:
Gary, Dave, John,
Thanks for the replies!
I removed the knob this afternoon and it is in good shape.
It looks like the set screw presses against a fiber like bushing that
surrounds the shaft and this presses against the shaft for a tight fit.
It did not feel stuck but I cannot turn it by just grabbing the shaft
with my fingers.
The shaft is round without a flat spot so I guess it is just a tight
compression fit that does the work.
I can move the switch to all three positions with a pair of pliers and
LSB/USB works just fine !!!
I may open it up and look at the underside and then try some lubricant
of some sort on the shaft, any suggestions?
I have WD40 & PB Blaster here to loosen it up some to start but maybe
some kind of light oil after that?
Dave KC3AM
On 3/20/2023 9:50 PM, Gary Follett wrote:
That knob? should most certainly operate with a click at each
position, allowing reception of AM, USB and LSB/CW.
There are two possibilities. One is simple, that the set screw for
the knob is loose. I think this is a setscrew type knob¡
If the set screw is very tight but you still cannot get a switch
action, remove the knob and have a look at the shaft. Try to turn it
gently with a pliers. If you get the same result, remove the cover
and have a look at the coupling between the small inner shaft and the
switch behind it to see if it is loose or broken. That coupling is
below the chassis (underside) towards the back, with the shaft going
between the coils of the bandpass filter coils.
Try that. If no joy, I have the last possibility you. Don¡¯t want to
hear unless you are really good at repair work.
Gary
W0DVN
On Mar 20, 2023, at 8:28 PM, Dave via groups.io
<kc3am@...> wrote:
Hello everyone,
Last summer I picked up a 2-C to go with my 2-NT.
I have been using it for CW without any troubles.
I tried to listen to some SSB signals tonight and I found a problem...
I cannot tune in the SSB signals, the mode control just spins around
and has no effect.
This is the first time I have tried to listen to SSB so this is new
to me.
Looking at the schematic before I open it up it looks like the mode
switch should have a few positions to it and not just spin around.
Am I correct?
Thanks much,
Dave KC3AM
|
Re: R4C 1500hz crystal filter damaged
Rob,
I can see the problem with the glass seal failing. ?It¡¯s pretty clear looking carefully at the pin. ?My other three filters are Network Science and I think they will simply never be taken out. ??
I¡¯m trying the JB weld solution and will post the result. ?If it fails I¡¯ll be looking for a new used one, or one from that company that currently sells drake filters.?
heck, it¡¯s only about 48 year old.
thanks Rob and all.
|
Rob Sherwood
Doug Crompton WA3DSP
Paul Christensen