"Mike Williams" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Thanks Jason,
good tips all; I have not used this amp for 15 years; it was part of the 4 C
line I purchased from my father in law. The R4C and T4XC are used regularly
on cw and phone and still perform great. Reviving the amp after some
storage damage...
Regards from Pompano Beach,
Mike W4DL
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: "Mike Williams" <[EMAIL PROTECTED]>
Cc: "Drakelist" <drakelist@www.zerobeat.net>
Sent: Tuesday, December 06, 2005 8:47 AM
Subject: Re: [drakelist] L4B being revivied
[EMAIL PROTECTED] made an utterance to the drakelist gang
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On Mon, 5 Dec 2005, Mike Williams wrote:
I am seeking a set of 3-500Z's and chimneys for a L4B I am in the
process of renovating; they need not be factory fresh by any means; just
have enough transconductance left to pump a few hundred watts! If you
have any sitting around, let me know how much you want for them!
Try to find some chimneys with the tapered tops to push air across the
anode seal and plate heat dissipator. If you use glass cylinders that are
not tapered at the top (Coleman lantern glass) you might as well not use
any at all. This depends on your operating style, however. If you rarely
run the tubes beyond dull gray with a tint of red you can get by without a
proper chimney. If you run the tubes red to almost orange (pretty easy to
do with 3-400Z) you will want chimneys with the tapered rim. The glass
envelope can take more heat than the anode seal where the pin comes
through the glass.
As for the tubes, my recommendation would be to buy from someone who has
used tubes in good working condition (sometimes Tom's Tubes has some nice
ones that are used). I've blown a lot of money on crap sold at the
auction sites - I have a shelf of dead 3-400Z and 3-500Z tubes that were
"sold as is" - $300 worth of junk that would have bought a NEW matched
pair of 3-500ZG. Late model 3-500Z Eimac tubes are prone to leaks and
usually fail immediate on turn-on if they haven't been used for 10+ years.
Last but not least, if you see about 2500V in SSB position and 160mA or
more idle plate current you might want to consider good chimneys because
the tubes will get awfully hot. My L4 will deliver 650W with 65W drive in
the CW position with 3-400Z and it will run forever on any band - do this
in SSB mode for another 2dB (1100W) without good chimneys and you'll melt
the solder in the tube pins and ruin your tank coil or bandswitch on WARC
(17m operation for example).
Sorry if i'm sounding preachy. Hope this helps.
--
73 Jason N1SU
http://n1su.com/
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