Re: Early 4 Line supplies
Interesting discussion here ...
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On 1/31/25 17:12, Stan Gammons via groups.io wrote: I have one of those little testers.? Capacitor checks seem to be close
to what my much older Sencore LC75 meter shows.?? The Sencore meter will
check leakage at various voltages. Not able to do that with the little
tester.
Good luck with your project.
73
Stan
KM4HQE
On 1/31/25 14:43, DavidC KD4E via groups.io wrote:
Received the caps and an ESR tester.
So far, so good ...
See attached pic.
On 1/27/25 20:55, Tony Sokol via groups.io wrote:
? ? ?I just wanted to make a comment here. David spent a bit of time
making sure he was ordering the right parts. I think ¡°wasting money ¡°
with the kits is a bit harsh. That extra money amounts to paying
someone to source and confirm the various components which is not
second nature like it is to us old far¡er¡folks. I¡¯m really glad to
see younger folks with a desire to learn which end of the soldering
iron to pick up.
? ? ? By the way, I was in the 7th grade when I first picked up a
soldering iron. :-) ?Got my call in ¡®54. Where the heck does the time
go. Oh wait, that¡¯s what old people say. ;-)
Tony - W9JXN
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Re: TR-4C Problems with 28.0 and 28.5 bands
Thanks for the tip! I will try this as soon as I can get the replacement resistors installed. I do have a nice scope.
73, Dave KD5FX
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Re: R-4C Filter Insertion Loss?
Actually T-7C reduces the noise bandwidth of the third mixer. ?It doesn¡¯t change the gain. ?Rob, NC0B?
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On Jan 31, 2025, at 4:40?AM, Jim VE7RF via groups.io <jim.thom@...> wrote:
?
AFAIK,? the R4C used a different tap on? (I think) the IF section, to increase the gain when using the CW filters, due to their higher, inherent insertion loss.?
On a similar note,? years ago, I bought a? new 125 hz? xtal filter from Inrad, for use in my yaeus's..... and the insertion loss was 9-10 db worse then the yaesu 250 hz filter.? It's semi useable.? I ended up removing it, and replaced with? the oem? 250 hz.?
?
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Re: Early 4 Line supplies
I have one of those little testers.? Capacitor checks seem to be close
to what my much older Sencore LC75 meter shows.?? The Sencore meter will
check leakage at various voltages. Not able to do that with the little
tester.
Good luck with your project.
73
Stan
KM4HQE
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Show quoted text
On 1/31/25 14:43, DavidC KD4E via groups.io wrote: Received the caps and an ESR tester.
So far, so good ...
See attached pic.
On 1/27/25 20:55, Tony Sokol via groups.io wrote:
? ? ?I just wanted to make a comment here. David spent a bit of time
making sure he was ordering the right parts. I think ¡°wasting money ¡°
with the kits is a bit harsh. That extra money amounts to paying
someone to source and confirm the various components which is not
second nature like it is to us old far¡er¡folks. I¡¯m really glad to
see younger folks with a desire to learn which end of the soldering
iron to pick up.
? ? ? By the way, I was in the 7th grade when I first picked up a
soldering iron. :-) ?Got my call in ¡®54. Where the heck does the time
go. Oh wait, that¡¯s what old people say. ;-)
Tony - W9JXN
|
Matteo, you are not crazy but you must be determined. The distortion tells me something is amiss with the AGC system -- incorrect AGC voltage or bad interstage coupling caps putting B+ on the grids.
?
As for T11, the easiest way is to watch eBay for the part to show up. You can certainly build a new coil, or perhaps adapt a new part that you find with Google, but that will be more work.
?
Good luck, and keep us posted.
?
Dave
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Re: Early 4 Line supplies
Received the caps and an ESR tester.
So far, so good ...
See attached pic.
toggle quoted message
Show quoted text
On 1/27/25 20:55, Tony Sokol via groups.io wrote: ? ? ?I just wanted to make a comment here. David spent a bit of time making sure he was ordering the right parts. I think ¡°wasting money ¡° with the kits is a bit harsh. That extra money amounts to paying someone to source and confirm the various components which is not second nature like it is to us old far¡er¡folks. I¡¯m really glad to see younger folks with a desire to learn which end of the soldering iron to pick up.
? ? ? By the way, I was in the 7th grade when I first picked up a soldering iron. :-) ?Got my call in ¡®54. Where the heck does the time go. Oh wait, that¡¯s what old people say. ;-)
Tony - W9JXN
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Good morning friends of the Drake group. I have been given a faulty rx R-4B as a gift. I overhauled the power supply part which was found to be faulty. The radio now turns on receives its internal marker, the preselector works . But the signal is very distorted. The s-meter goes full scale left to negative. Continuing the checks I found the T11 transformer broken and with the internal coils charred. I think it is impossible to find a T11 as a replacement or at least to know the characteristics in order to rebuild it. Another possibility would be to redesign with modern components this part of the circuit also inserting a new product detector. What do you think ? am I crazy?
Best regards 73 de Matteo ik2gsr
?
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I did not find any ¡®4427¡¯s. I¡¯ll find the spreadsheet later as I have an appointment to make at the moment.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Jan 31, 2025 at 10:50, Steve Wedge, W1ES/4 via groups.io < w1es@...> wrote:
That number looks familiar. I¡¯ve been meaning to post my spreadsheet of available transistors that I sorted from a tacklebox full of randomly-mixed parts.?
I will try and remember to do this shortly. Feel free to nag me if I forget.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Jan 31, 2025 at 10:24, Jim Harris via groups.io <
radiove1rb@...> wrote:
Thank you Jim for that bit of information. ,I replaced the transistor a few years ago working on it but just got around to working on it again.
Regards, Jim
Our records show having replaced a few of these over the years.? BM and the buffer.? Almost sounds like it qualifies for common failure analysis. The 2n4427 has unique properties, not easily substituted.? ?
Jim WA9Z
Exline IA
?
?
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The 2n4427 has unique properties, not easily substituted.? ? Jim WA9Z Exline IA ? Possibly 2N5109 as a viable substitute.? Not easily found these days but here¡¯s one source: ?
? Paul, W9AC
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That number looks familiar. I¡¯ve been meaning to post my spreadsheet of available transistors that I sorted from a tacklebox full of randomly-mixed parts.?
I will try and remember to do this shortly. Feel free to nag me if I forget.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Jan 31, 2025 at 10:24, Jim Harris via groups.io < radiove1rb@...> wrote:
Thank you Jim for that bit of information. ,I replaced the transistor a few years ago working on it but just got around to working on it again.
Regards, Jim
Our records show having replaced a few of these over the years.? BM and the buffer.? Almost sounds like it qualifies for common failure analysis. The 2n4427 has unique properties, not easily substituted.? ?
Jim WA9Z
Exline IA
?
?
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Thank you Jim for that bit of information. ,I replaced the transistor a few years ago working on it but just got around to working on it again.
Regards, Jim
Our records show having replaced a few of these over the years.? BM and the buffer.? Almost sounds like it qualifies for common failure analysis. The 2n4427 has unique properties, not easily substituted.? ?
Jim WA9Z
Exline IA
?
?
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Re: TR-4C Problems with 28.0 and 28.5 bands
Probably a good idea if you have questions about something else in this set :-)
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Jan 31, 2025 at 09:26, Dave KD5FX via groups.io < land.dave@...> wrote:
Yes, can cap was already replaced before I got this radio. He didn't put a new can style in it, he used individual caps.
This tread is very long now. The original problem is solved with the baked Xtals. Should I start a new thread?
73, Dave KD5FX
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Our records show having replaced a few of these over the years.? BM and the buffer.? Almost sounds like it qualifies for common failure analysis. The 2n4427 has unique properties, not easily substituted.? ?
Jim WA9Z
Exline IA
?
?
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Re: TR-4C Problems with 28.0 and 28.5 bands
Yes, can cap was already replaced before I got this radio. He didn't put a new can style in it, he used individual caps.
This tread is very long now. The original problem is solved with the baked Xtals. Should I start a new thread?
73, Dave KD5FX
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Re: R-4C Filter Insertion Loss?
Ciao
?
Ho sostituito i vecchi filtri originali nella mia r-4c anni fa, e sia i 500 che i 250 Hz hanno una perdita di circa 6 dB...
Ho acquistato la stessa coppia di filtri da Noble Radio... NESSUNA PERDITA.
?
Paul IK1QHB?
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It is my intent to do so.
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Jan 30, 2025 at 8:00 PM, Gene Balinski K1NR via groups.io < g.balinski@...> wrote:
Please publish your results.? ?They will be very helpful to the group
?
73
K1NR
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Re: R-4C Filter Insertion Loss?
AFAIK,? the R4C used a different tap on? (I think) the IF section, to increase the gain when using the CW filters, due to their higher, inherent insertion loss.?
On a similar note,? years ago, I bought a? new 125 hz? xtal filter from Inrad, for use in my yaeus's..... and the insertion loss was 9-10 db worse then the yaesu 250 hz filter.? It's semi useable.? I ended up removing it, and replaced with? the oem? 250 hz.?
?
|
Re: R-4C Filter Insertion Loss?
Rob wrote: "Note that aligning T-7C that appears in S/N 21,000 and above is critical and should be peaked on the narrowest bandwidth filter."
?
Cool...mine is 26xxx (loaded with your mods btw) so will look at that slug. thanks
--
Craig/W8CS
Greenville, SC
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Please publish your results.? ?They will be very helpful to the group
?
73
K1NR
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Re: R-4C Filter Insertion Loss?
Hi Craig,
?
Any crystal or multiple crystals in a filter can degrade, increasing the insertion loss that can also degrade the passband shape.
?
The original insertion loss spec for all the R-4C filters was 9 dB +2 dB / -1 dB (8 to 11 dB).? ?Wider-bandwidth lower-loss filters were to have additional
loss added to keep the net loss within that spec. As time passed, adding loss to the wider filters was abandoned at least by some OEMs making filters for Drake.? Up to 50 years later a given filter my still meet spec or have very excessive insertion loss.
?
Note that aligning T-7C that appears in S/N 21,000 and above is critical and should be peaked on the narrowest bandwidth filter.
?
Rob, NC0B
? ????
?
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From: [email protected] [mailto:[email protected]]
On Behalf Of Craig W8CS via groups.io
Sent: Thursday, January 30, 2025 9:26 AM
To: [email protected]
Subject: [DRAKE-RADIO] R-4C Filter Insertion Loss?
?
Is it normal to see a big insertion loss with the Network Sciences filters? I see a huge insertion loss with the 250Hz filter, and also somewhat degraded with the 1500Hz filter. These date 76/77 so not sure if they accumulate loss with
age. Fortunately I mostly use 500/SSB filters, but the loss renders especially the 250Hz filter to be almost useless.?
I've swapped them with the 500Hz socket and the loss follows the filter itself.?
Just curious if y'all have seen something similar. Thanks
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DavidC KD4E
Rob Sherwood
Paul Christensen
Craig W8CS