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Today's Topics:
1. L-4B/L7 Power Supply Rebuilds (Dino Papas)
2. Re: Microphone for 4 line (Steve Wedge)
3. Re: Microphone for 4 line (kc9...@aol.com)
4. Re: L-4B/L7 Power Supply Rebuilds (K9sqg)
----------------------------------------------------------------------
Message: 1
Date: Sat, 18 Feb 2012 14:22:46 -0500
From: Dino Papas <k...@cox.net>
To: Mail List - Drake Gear Drake Gear <drakelist@zerobeat.net>
Subject: [Drakelist] L-4B/L7 Power Supply Rebuilds
Message-ID: <ffe8a9f6-02cf-4703-9d3c-f168e7586...@cox.net>
Content-Type: text/plain; charset=us-ascii
I finally bit the bullet yesterday and got around to rebuilding my
L-4BPS and L7PS supplies, one with a Heathkit Shop board and the
other with the Harbach version. Both procedures went well, with
the second going a LOT faster than the first! I will be rebuilding
a friend's L-4BPS next week and figured I could minimize the time
to do his by working out the bugs doing mine.
As my L-4B is my main amp, and based on Evan's note to me a few
years ago, I went ahead and changed out the 5K 7W resistor with the
13W version, replaced the 0.82 ohm HV line resistor and the 50K 50W
bleeders as a precautionary measure. In the other amp I guess I
was just lazy and simply installed only the Harbach board.
Now sitting here thinking about it should I go back and just get it
over with and replace the resistors in the L7PS? Has anyone ever
had a bleeder go bad? Or the others for that matter. Sure, age
will wear anything down.
Also, the Harbach board doesn't include the diode balancing
resistors that Mike's board does...as the original Drake diode
strings used 'em what exactly is the difference? Do modern (read
that "better") diodes still need that protection? I'm just curious.
I was pretty impressed that my 32 year old L-4BPS kept going like
the Energizer Bunny all these years and I didn't notice any
deterioration at all on the bodies of the orange
electrolytics....but, better safe than sorry and I'm looking
forward to many more years of reliable operation with both amps.
Thoughts?
Dino KL0S
------------------------------
Message: 2
Date: Sat, 18 Feb 2012 19:59:36 -0500
From: "Steve Wedge" <w1es1...@earthlink.net>
To: "ko1h" <k...@cox.net>, <Drakelist@zerobeat.net>,
<drakera...@yahoogroups.com>
Subject: Re: [Drakelist] Microphone for 4 line
Message-ID: <DDCFB671A1254856BB7C1D941F736D3D@STEVE2>
Content-Type: text/plain; charset="iso-8859-1"
John, I believe you can get high-Z elements from Heil, if you want
to keep the old 444.
I use a stone-stock, no preamp D-104 and get excellent reports.
Steve Wedge, W1ES/4
"I can't complain, but sometimes I still do."
- Joe Walsh
If the above message appears, it came from Steve's Son of Laptop!
----- Original Message -----
From: ko1h
To: Drakelist@zerobeat.net ; drakera...@yahoogroups.com
Sent: Saturday, February 18, 2012 5:55 AM
Subject: [Drakelist] Microphone for 4 line
HI all, I just got my R4/t4 pair back from restoration and well
my old shure444 isn't getting good reports. I was wondering what
microphone currently in production is the consensus to use now? I
see replacement elements for the 444 but I'm not sure I want to go
that route. Heil used to make a high impedance mic but I don't
they do do any longer? What are ya'll using? What do you recommend?
Thanks for opinion etc
de John ko1h
PS if anyone is looking to sell a TR4 in need of slight tlc or
just cosmetics please contact me
k...@cox.net
----------------------------------------------------------------------
--------
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Message: 3
Date: Sat, 18 Feb 2012 21:43:33 -0500 (EST)
From: kc9...@aol.com
To: k...@cox.net, Drakelist@zerobeat.net, drakera...@yahoogroups.com
Subject: Re: [Drakelist] Microphone for 4 line
Message-ID: <8cebcc73cab8929-1cb4-12...@webmail-d062.sysops.aol.com>
Content-Type: text/plain; charset="utf-8"; format=flowed
I use the Heil Classic with the switch selectable narrow/wide on WIDE.
Get great audio reports all the time...from thise that know me.
73,
Lee
-----Original Message-----
From: ko1h <k...@cox.net>
To: Drakelist <Drakelist@zerobeat.net>; drakeradio
<drakera...@yahoogroups.com>
Sent: Sat, Feb 18, 2012 5:57 am
Subject: [Drakelist] Microphone for 4 line
HI all, I just got my R4/t4 pair back from restoration and well my old
shure444 isn't getting good reports.? I was wondering what microphone
currently in production is the consensus to use now?? I see
replacement
elements for the 444 but I'm not sure I want to go that route.? Heil
used to make a high impedance mic but I don't they do do any longer??
What are ya'll using?? What do? you recommend?
?
Thanks for opinion etc
?
de John ko1h
?
PS if anyone is looking to sell a TR4 in need of slight tlc or just
cosmetics please contact me
?
k...@cox.net
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Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
------------------------------
Message: 4
Date: Sat, 18 Feb 2012 23:04:08 -0500 (EST)
From: K9sqg <k9...@aol.com>
To: k...@cox.net, drakelist@zerobeat.net
Subject: Re: [Drakelist] L-4B/L7 Power Supply Rebuilds
Message-ID: <8cebcd2aa0881b6-1168-39...@webmail-m029.sysops.aol.com>
Content-Type: text/plain; charset="us-ascii"
Dino et. al.
Well, let me briefly relate what I have observed and encountered
when rebuilding L4, L4B, and L7 power supplies. Your mileage might
vary.
My experience has been that the supplies I have worked on have had
in excess of a 50% failure rate, and maybe another 25% had whitish
or light gray regions, typically toward one end, where there has
been excessive heating suggesting and impending failure. Having a
stock of the resistors on hand, and having the supply apart, it was
a quick job to replace the bleederrs for safety and better
regulation. Many people have failed bleeders and are totally
unaware of it.
There is generally better quality control with diodes nowadays
compared to decades ago. Still, for as cheap as resistors are, it
is a small price to pay for an added measure of protection, can't
hurt. There are two schools of thoughts on this topic so one goes
with the one that is most appealing.
Final note on that 5K 7wt resistor on the underside of the supply,
I too replace it during a standard rebuild and use two 10K 10wt
resistors in parallel. Unknown to many, when the original opens,
it takes out the ALC pot which, for the L4B I haven't seen in 30
except the ones I have in stock.
Enjoy those Drakes, the Drake Nets, and our hobby.
73,
Evan, K9SQG
-----Original Message-----
From: Dino Papas <k...@cox.net>
To: Mail List - Drake Gear Drake Gear <drakelist@zerobeat.net>
Sent: Sat, Feb 18, 2012 2:24 pm
Subject: [Drakelist] L-4B/L7 Power Supply Rebuilds
I finally bit the bullet yesterday and got around to rebuilding my
L-4BPS and
L7PS supplies, one with a Heathkit Shop board and the other with
the Harbach
version. Both procedures went well, with the second going a LOT
faster than the
first! I will be rebuilding a friend's L-4BPS next week and
figured I could
minimize the time to do his by working out the bugs doing mine.
As my L-4B is my main amp, and based on Evan's note to me a few
years ago, I
went ahead and changed out the 5K 7W resistor with the 13W version,
replaced the
0.82 ohm HV line resistor and the 50K 50W bleeders as a
precautionary measure.
In the other amp I guess I was just lazy and simply installed only
the Harbach
board.
Now sitting here thinking about it should I go back and just get it
over with
and replace the resistors in the L7PS? Has anyone ever had a
bleeder go bad?
Or the others for that matter. Sure, age will wear anything down.
Also, the Harbach board doesn't include the diode balancing
resistors that
Mike's board does...as the original Drake diode strings used 'em
what exactly is
the difference? Do modern (read that "better") diodes still need that
protection? I'm just curious.
I was pretty impressed that my 32 year old L-4BPS kept going like
the Energizer
Bunny all these years and I didn't notice any deterioration at all
on the bodies
of the orange electrolytics....but, better safe than sorry and I'm
looking
forward to many more years of reliable operation with both amps.
Thoughts?
Dino KL0S
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Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
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End of Drakelist Digest, Vol 44, Issue 35
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