Dentron GLA-1000
Hi guys,
Well it soundl like you got what I had. Parasitic Oscillation.
If you watch the current meter it will slowly creep up then bam...max and
the fuse goes Bang! If you watch the tubes they turn real white just
before the fuse blows. The amps are real sensitive to tube current
inbalance and matched sets of 6lq6's are almost required You could try
un-matched tubes and put some current limiting resistors across the
cathodes and try to balance them that way. .
I went thru two good sets of 6lq6's ($200/set of match!) and a 3rd set of
used ones AND two Zener diodes before I gave up. I wont mention the
capacitor deck I had to replace previously. I came across a MLA-2500
and sold the GLA-1000 to a friend of mine who guessed what what the
problem was and wanted to fix it. He downloaded some mod information from
www.svetlana.com about converting the 6LQ6's to some EL- equv tube. I
think he paid around $15/ea for some yugoslavian type and made the mod
which includes the Parasitic Oscillation fix and the amp is running rock
solid again.
For what its worth....I would be suprised if your tubes are any good
anymore and check the zener too.
73 Chuck KR6C
On Mon, 1 Mar 1999 23:45:23 -0500 (EST) owner-amps-digest@contesting.com
(Amps Digest) writes:
>
>Amps Digest Monday, March 1 1999 Volume 02 :
>Number 089
>
>
>
>In this issue:
>
> [AMPS] Ig
> RE: [AMPS] Re: Blower
> [AMPS] screen regulators
> Re: [AMPS] screen regulators
> [AMPS] SB220 Xformer labodomy-cont'd
> Re: [AMPS] SB220 Xformer labodomy-cont'd
> Re: [AMPS] SB220 Xformer labodomy-cont'd
> [AMPS] Dentron GLA-1000
> [AMPS] Nichicon Capacitors?
> Re: [AMPS] Ig
> [AMPS] AC rating vs. DC rating on caps.
> Re: [AMPS] SB220 Xformer labodomy-cont'd
>
>See the end of the digest for information about amps-digest
>
>----------------------------------------------------------------------
>
To: <amps@contesting.com>
>Date: Sun, 28 Feb 1999 20:53:02 -0800
>From: zeitler@ibm.net
>Subject: [AMPS] Ig
>
>Is anyone (or is it anybody? Where's Rich when you really need him)
>ever set
>up their amps to measure Ig independently instead of measuring all of
>the Ig
>at the same time (multi tube amps)?
>
>I have some back up tubes for my L4B. One of them is an OLD Eimac
>3-500Z
>(has the Amperex looking fins) and an even older Eimac 3-400Z. In an
>emergency situation I want to be able to insert these tubes as backups
>and
>run them as a set. Would like to be able to monitor the Ig of each to
>ensure
>proper operation since they are somewhat mismatched.
>
>Lane Zeitler
>Ku7i
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 1 Mar 1999 10:25:50 -0000
>From: Peter Chadwick <Peter_Chadwick@mitel.com>
>Subject: RE: [AMPS] Re: Blower
>
>Frank, W3LPL, says:
>
>> After 25 years of
>>service and
>>500,000 DX Contest QSOs, I only had to replace two tubes.
>
>Now, Frank, we can't have this. Everyone knows that tubes are fragile,
>unreliable, wear out, etc. That's why we have semiconductors!!
>
>73
>
>Peter G3RZP
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 1 Mar 1999 13:52:36 -0000
>From: Peter Chadwick <Peter_Chadwick@mitel.com>
>Subject: [AMPS] screen regulators
>
>One caveat on adding FETs in shunt to get the power handling up in a
>screen
>grid shunt regulator that I didn't see on Rich's web page (but I
>could have
>missed it) is that you need to make sure they share the current
>equally.
>Series resistors in the source are a good way.
>
>73
>
>Peter G3RZP
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 1 Mar 1999 10:02:28 -0800
>From: Rich Measures <measures@vc.net>
>Subject: Re: [AMPS] screen regulators
>
>>
>>One caveat on adding FETs in shunt to get the power handling up in a
>screen
>>grid shunt regulator that I didn't see on Rich's web page (but I
>could have
>>missed it) is that you need to make sure they share the current
>equally.
>>Series resistors in the source are a good way.
>
>? I do not use FETs in the screen shunt-regulator. I use FETs in the
>
>screen series-regulator. In the latter, I use Source (neg. feedback)
>resistor(s) as current-equalizers and to suppress osc. around 100MHz.
>
>- - cheers
>
>
>
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 01 Mar 1999 13:43:36 -0500
>From: Len Schaier <lschaier@avotec.com>
>Subject: [AMPS] SB220 Xformer labodomy-cont'd
>
>Hello again:
>
>I've done a little homework and found that the polyester resin from
>Evercoat
>and carried at Home Depot will start to degrade at 150 degrees F (66
>C).
>Their epoxy product, however, has better thermal conductivity and will
>operate at much higher temperatures. Its application viscosity is
>about the
>same as the resin.
>
>Questions:
>1-Anybody have a clue as to what the winding temps will be in an SB220
>xformer?
>2-Has anybody tried epoxy for potting power transformers?
>
>Len
>
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 1 Mar 1999 12:07:23 -0800
>From: Rich Measures <measures@vc.net>
>Subject: Re: [AMPS] SB220 Xformer labodomy-cont'd
>
>>
>>Hello again:
>>
>>I've done a little homework and found that the polyester resin from
>Evercoat
>>and carried at Home Depot will start to degrade at 150 degrees F (66
>C).
>
>? cured polyester resin or uncured?
>thanks, Len
>
>
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 01 Mar 1999 16:12:08 -0500
>From: Len Schaier <lschaier@avotec.com>
>Subject: Re: [AMPS] SB220 Xformer labodomy-cont'd
>
>Rich,
>
>Cured polyester resin.
>
>Len
>
>
>
>At 12:07 PM 3/1/99 -0800, Rich Measures wrote:
>>>
>>>Hello again:
>>>
>>>I've done a little homework and found that the polyester resin from
>Evercoat
>>>and carried at Home Depot will start to degrade at 150 degrees F (66
>C).
>>
>>? cured polyester resin or uncured?
>>thanks, Len
>>
>>
>>Rich...
>>
>>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>>
>>
>>
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 1 Mar 1999 16:14:15 -0500
>From: "Mark A. Mowery" <mowery@shianet.org>
>Subject: [AMPS] Dentron GLA-1000
>
>Hi all,
>
>I need some help with my humble GLA 1000. It's developed the nasty
>habit of
>blowing fuses after only a few minutes in the "standby" mode. And when
>they
>go, they don't just simply melt, they go with a distinct audible
>"pop".
>I've had the amp apart and looked for anything obviously wrong, don't
>see
>any visible damage, evidence of arcing, burning, etc. No funny smells,
>no
>smoke.
>
>What say you, amp gurus? Where should I start? Could this be a tube
>problem? Or is this the excuse I needed to buy that new Commander?
>
>Mark AA8TC
>- ---------------------------------------------------------------
>"A ham and his quad - it's a beautiful thing."
>http://www.qrz.com/wrad/directory.cgi?AA8TC
>http://www.shianet.org/~mowery
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 01 Mar 1999 21:55:35 GMT
>From: geo@ipass.net (George McCrary)
>Subject: [AMPS] Nichicon Capacitors?
>
>Hello Folks,
>
> Has anyone determined if the Nichicon 470 uF at 450v caps that
>All Electronics is selling are suitable for use in amp power supply
>design? I have the Nichicon Catalog and can look up the specs, but how
>can I determine their suitability? I want to build a 4000 volt 750 mA
>supply using 10 of these in series. All Electronics is selling them
>for $3 each or 10 for $22.50 which makes them very attractive.
>
> I would also welcome other suggestions for a source of caps
>for the power supply.
>
> Regards,
>
> George (KQ4QM)
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 01 Mar 1999 23:32:24 +0000
>From: f117ab@ameritech.net
>Subject: Re: [AMPS] Ig
>
>Lane,
>Sure. That's the way my 6 X 2c39 is set up. Matching 6 tubes is quite
>a
>challenge. individual bias supplies and metering helps. . .however,
>separate
>supplies are used. It might be more of a challenge to get separate
>grid current
>readings from one supply. . .
>Art k9xf
>
>zeitler@ibm.net wrote:
>
>> Is anyone (or is it anybody? Where's Rich when you really need him)
>ever set
>> up their amps to measure Ig independently instead of measuring all
>of the Ig
>> at the same time (multi tube amps)?
>>
>> I have some back up tubes for my L4B. One of them is an OLD Eimac
>3-500Z
>> (has the Amperex looking fins) and an even older Eimac 3-400Z. In an
>> emergency situation I want to be able to insert these tubes as
>backups and
>> run them as a set. Would like to be able to monitor the Ig of each
>to ensure
>> proper operation since they are somewhat mismatched.
>>
>> Lane Zeitler
>> Ku7i
>>
>> --
>> FAQ on WWW: http://www.contesting.com/ampfaq.html
>> Submissions: amps@contesting.com
>> Administrative requests: amps-REQUEST@contesting.com
>> Problems: owner-amps@contesting.com
>> Search: http://www.contesting.com/km9p/search.htm
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 1 Mar 1999 16:38:42 -0800
>From: "W6NQ" <w6nq@rfparts.com>
>Subject: [AMPS] AC rating vs. DC rating on caps.
>
>I don't recall what an equivalent dc rating might be on oil filled
>(non PCB)
>caps. In particular, the Aerovox p/n H83R6654S21, 54 uf. 660vac @ 60
>cps.
>Thanks, Merit W6NQ
>
>------------------------------
>
To: <amps@contesting.com>
>Date: Mon, 1 Mar 1999 17:27:46 -0800
>From: Rich Measures <measures@vc.net>
>Subject: Re: [AMPS] SB220 Xformer labodomy-cont'd
>
>>
>>Rich,
>>
>>Cured polyester resin.
>>
>? surprising. What temp for the epoxy?
>- - I wound a transformer 21 years ago which I potted in polyester
>
>laminating resin. So far, no problems.
>
>- - thanks, Len
>>
>>
>>
>>At 12:07 PM 3/1/99 -0800, Rich Measures wrote:
>>>>
>>>>Hello again:
>>>>
>>>>I've done a little homework and found that the polyester resin from
>Evercoat
>>>>and carried at Home Depot will start to degrade at 150 degrees F
>(66 C).
>>>
>>>? cured polyester resin or uncured?
>>>thanks, Len
>>>
>>>
>>>Rich...
>>>
>>>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>>>
>>>
>>>
>>
>>
>>
>>
>>--
>>FAQ on WWW: http://www.contesting.com/ampfaq.html
>>Submissions: amps@contesting.com
>>Administrative requests: amps-REQUEST@contesting.com
>>Problems: owner-amps@contesting.com
>>Search: http://www.contesting.com/km9p/search.htm
>>
>
>
>
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>
>------------------------------
>
>End of Amps Digest V2 #89
>*************************
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampfaq.html
>Submissions: amps@contesting.com
>Administrative requests: amps-digest-REQUEST@contesting.com
>Problems: owner-amps-digest@contesting.com
>
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