Re: LK-500 AMP-
Actually Omega Electronics has a better parasite suppressor.Or just
make sure you have not cooked the resistor in your suppressor. It's supposed
to dissipate the parasite and load the small coil properly, no (open)
resistor because
it died an honorable death trying to do it's job, I'm thinking.
No "Black Magic" type circuit here.
I beg to differ, my LK-500B or C had no temp sensing. I added it to the
B so as not to cut up the cabinet with a switch hole. I left the switch in
the C
without thermostats as I did in the "B"and am quite satisfied.
If you provide ventilation space on the right hand side of the cabinet there
is no
need for additional fans, IMHO.
Re- the earlier comment on Drake, I too had a muffin fan over the PA section
to keep the sweep tubes happy. Worked fine
The SB-200 uses an old phono motor and a metal fan that is virtually
useless. Yes
it doesn't discolor, but it also doesn't cool the tubes and the amplifier.
Solution is
open the top cover and add a muffin fan. Kinda ugly but it works.
ed K0KL
----- Original Message -----
From: <amps-request@contesting.com>
To: <amps@contesting.com>
Sent: Wednesday, August 15, 2007 11:00 AM
Subject: Amps Digest, Vol 56, Issue 20
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> Today's Topics:
>
> 1. Re: Project for 8122 tubes (jeremy-ca)
> 2. [Fwd: Re: LK 500 ZA heat] (alexander a. aimette)
> 3. Re: [Fwd: Re: LK 500 ZA heat] (Tom Rauch)
> 4. Re: [Fwd: Re: LK 500 ZA heat] (jeremy-ca)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 14 Aug 2007 15:17:29 -0400
> From: "jeremy-ca" <km1h@jeremy.mv.com>
> Subject: Re: [Amps] Project for 8122 tubes
> To: "Pat Barthelow" <aa6eg@hotmail.com>, <amps@contesting.com>
> Message-ID: <011b01c7dea7$c3f50d30$6500a8c0@KITTYMA123>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Not that Ive ever noticed. I have some used ones with late 60's date codes
> that are fine. I also picked up a distributed amp with 13 NOS 1983 date
> codes recently. They were all fine after a 5 minute warm up when I then
used
> the original National test jig to match them. Got nice prices on Ebay.
>
> The Eimac 8122W often has a much higher bias requirement than the RCA and
is
> out of range of the bias pot. Its a simple matter to move the range from
the
> stock -25 to -45V up to -35 to -55V. The Eimac has a bias range about half
> that of the RCA so they still require matching.
>
> Carl
> KM1H
>
>
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Pat Barthelow" <aa6eg@hotmail.com>
> To: <amps@contesting.com>
> Sent: Tuesday, August 14, 2007 12:42 PM
> Subject: Re: [Amps] Project for 8122 tubes
>
>
> > folks:
> > Are 8122 Tubes that have been in storage for possibly Decades without
use,
> > likely to have internal gas problems?
> >
> > Sincerely, Pat Barthelow aa6eg@hotmail.com
> > http://www.jamesburgdish.org
> > Jamesburg Earth Station Moon Bounce Team
> > http://www.cq-vhf.com
> >
> >>From: "sulai je" <7z1sj@jeeran.com>
> >>Reply-To: 7z1sj@jeeran.com
> >>To: <amps@contesting.com>
> >>Subject: [Amps] Project for 8122 tubes
> >>Date: Tue, 14 Aug 2007 13:03:08 +0300
> >>
> >>
> >>Hello
> >>I had some RCA 8122 tubes in my junk box since long time. Thinking to
use
> >>them in a homebrew project so I start to search for an amplifier
project!
> >>Either to UHF or VHF . HF Googling the net yields a zero project for
those
> >>tubes.
> >>
> >>if any on can help with schematic and more info I will be appreciated in
> >>advance .
> >>73s de 7z1sj Sulaiman
> >>_______________________________________________
> >>Amps mailing list
> >>Amps@contesting.com
> >>http://lists.contesting.com/mailman/listinfo/amps
> >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
>
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 14 Aug 2007 21:22:35 -0400
> From: "alexander a. aimette" <w2ox@verizon.net>
> Subject: [Amps] [Fwd: Re: LK 500 ZA heat]
> To: AMPS@CONTESTING.COM
> Message-ID: <46C2555B.5090809@verizon.net>
> Content-Type: text/plain; charset=us-ascii; format=flowed
>
>
>
> -------- Original Message --------
> Subject: Re: [Amps] LK 500 ZA heat
> Date: Mon, 13 Aug 2007 17:24:40 -0400
> From: alexander a. aimette <w2ox@verizon.net>
> To: dave arruzza <w1ctn@yahoo.com>
> References: <444028.48950.qm@web38209.mail.mud.yahoo.com>
>
>
>
> dave arruzza wrote:
>
> >Hello to all...
> >
> > My LK 500 ZA gets very hot when operated for any length of time. I do
not think that the stock fan is adequate for the job. I am planning on
adding at least one fan externally to pull out some of the hot air from the
3-500Z's.
> >
> > Has anyone else had this problem? With the amount of heat generated I
am sure that some other components inside that box are stressed from the
extreme heat. I just want to alleviate this condition before other parts
start to fail.
> >
> > I'm sure that the bandswitch problems associated with this linear are a
direct result of the heat retained within the box.
> >
> > Any ideas and mods are welcome.
> >
> > 73
> > Dave W1CTN
> >
> >
> >---------------------------------
> >Park yourself in front of a world of choices in alternative vehicles.
> >Visit the Yahoo! Auto Green Center.
> >_______________________________________________
> >Amps mailing list
> >Amps@contesting.com
> >http://lists.contesting.com/mailman/listinfo/amps
> >
> >
> >
> dear dave: I have owned and ran 3 lk500za amps in contests for years.
> Here are a couple of things you might consider, BASED ON ACTUAL
> EXPERIENCE--NOT THEORY.. There is also the comment that advice is worth
> what you pay for it!!!!
>
> 1-These amps are notorious for parasitics. EVERY ONE OF MY AMPS WAS
> FITTED OUT WITH the Ralph Measures 3-500z parasitic suppressers and I
> had no further problems--for 10 years, in every cqww and arrl test
> during those years. I replaced just two 3-500z tubes in all that time.
>
> 2-Some of these amps have a low and a high fan setting. I always used
> the high fan setting. There is also a temp sensing circuit which
> switches the fan to a high setting with a higher duty cycle. If this
> cicuit is not working that may be your problem..
>
> 3-The amps I had all were fitted with four fans in a wall behind the
> tubes. Check that they all work. Also note that the fans are usually
> very, very noisy on the high setting. If the fan noise is very quiet,
> then the fans are NOT working at the high rpm setting.
>
> 4-If you are running the amp at the 3500 dc high volt tap instead of the
> 3100v tap on the xfmr(just switch to the high voltage indication on the
> front panel, no load) you will have tuning capacitor arcing and
> bandswitch arcing problems on any load other than 1:1 SWR. This amp is
> not designed to operate at power levels of 1500w at other than 1:1.
> My amps ran well at 1200watts into loads up to 1:3 SWR.. I ran all
> of my amps at 1200-1300w MAX into low swr loads for years at v47kp
> without problems.
> If you insist on getting 1500w out, good luck!!
>
> 5-Drive power was limited to that which gave 1200w out, typically 70-100
> watts depending on the band.
>
> 6-I never ran the amp with the full break in system.
>
> alex aimette, w2ox/v47kp
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 14 Aug 2007 21:56:27 -0400
> From: "Tom Rauch" <w8ji@contesting.com>
> Subject: Re: [Amps] [Fwd: Re: LK 500 ZA heat]
> To: "alexander a. aimette" <w2ox@verizon.net>, <AMPS@CONTESTING.COM>
> Message-ID: <021601c7dedf$84a704c0$640fa8c0@radioroom>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> > 1-These amps are notorious for parasitics.
>
> Almost any failure in the world is blamed on parasitics.
> :-)
>
> EVERY ONE OF MY AMPS WAS
> > FITTED OUT WITH the Ralph Measures 3-500z parasitic
> > suppressers and I
> > had no further problems--for 10 years, in every cqww and
> > arrl test
> > during those years. I replaced just two 3-500z tubes in
> > all that time.
>
> How do you know your amp had parasitics?
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 14 Aug 2007 22:16:39 -0400
> From: "jeremy-ca" <km1h@jeremy.mv.com>
> Subject: Re: [Amps] [Fwd: Re: LK 500 ZA heat]
> To: "alexander a. aimette" <w2ox@verizon.net>, <AMPS@CONTESTING.COM>
> Message-ID: <01b101c7dee2$5230bf10$6500a8c0@KITTYMA123>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> >
> > 1-These amps are notorious for parasitics. EVERY ONE OF MY AMPS WAS
> > FITTED OUT WITH the Ralph Measures 3-500z parasitic suppressers
>
>
> You just said two very dirty words, Tom will now proceed to try and
castrate
> you.
>
> BTW, my LK500ZC has many many hours behind it including several ARRL and
CQ
> DX and WPX contest awards. I never once had a "parasitic" problem or lost
a
> tube since it was new in 1987. It has also tuned just fine into 3:1 and
> higher VSWR.
>
> Carl
> KM1H
>
>
>
> and I
> > had no further problems--for 10 years, in every cqww and arrl test
> > during those years. I replaced just two 3-500z tubes in all that time.
> >
> > 2-Some of these amps have a low and a high fan setting. I always used
> > the high fan setting. There is also a temp sensing circuit which
> > switches the fan to a high setting with a higher duty cycle. If this
> > cicuit is not working that may be your problem..
> >
> > 3-The amps I had all were fitted with four fans in a wall behind the
> > tubes. Check that they all work. Also note that the fans are usually
> > very, very noisy on the high setting. If the fan noise is very quiet,
> > then the fans are NOT working at the high rpm setting.
> >
> > 4-If you are running the amp at the 3500 dc high volt tap instead of the
> > 3100v tap on the xfmr(just switch to the high voltage indication on the
> > front panel, no load) you will have tuning capacitor arcing and
> > bandswitch arcing problems on any load other than 1:1 SWR. This amp is
> > not designed to operate at power levels of 1500w at other than 1:1.
> > My amps ran well at 1200watts into loads up to 1:3 SWR.. I ran all
> > of my amps at 1200-1300w MAX into low swr loads for years at v47kp
> > without problems.
> > If you insist on getting 1500w out, good luck!!
> >
> > 5-Drive power was limited to that which gave 1200w out, typically 70-100
> > watts depending on the band.
> >
> > 6-I never ran the amp with the full break in system.
> >
> > alex aimette, w2ox/v47kp
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
>
>
>
> ------------------------------
>
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> End of Amps Digest, Vol 56, Issue 20
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