If you provide ventilation space on the right hand side of the cabinet there
is no
need for additional fans, IMHO.
Agree. The only problem with the LK-500 series is inadequate area for the
hot air to exit. If you want HD suppressors you can buy them on line thru
Ameritron; order the ones for the AL-82.
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.
There is no need to go ugly if the SB-200 is run within the tube ratings and
not overdriven as usually is the case. The 572B doesnt require forced air
cooling, just a little bit of air circulation in those cramped quarters.
Carl
KM1H
----- Original Message -----
From: "Edwin Karl" <edk0kl@centurytel.net>
To: <amps@contesting.com>
Sent: Wednesday, August 15, 2007 12:45 PM
Subject: Re: [Amps] Amps Digest, Vol 56, Issue 20
> 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
>
>
>> Send Amps mailing list submissions to
>> amps@contesting.com
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> http://lists.contesting.com/mailman/listinfo/amps
>> or, via email, send a message with subject or body 'help' to
>> amps-request@contesting.com
>>
>> You can reach the person managing the list at
>> amps-owner@contesting.com
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of Amps digest..."
>>
>>
>> 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
>> >
>>
>>
>>
>> ------------------------------
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>> End of Amps Digest, Vol 56, Issue 20
>> ************************************
>>
>
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