If I sounded like I didn't like the SB-220, I didn't mean to. I was simply
warning the OP of a real problem that he is likely to run into if he
purchases an amp with 3-500Zs, if that amp has not been used for a long
time.
I based what I said on information that is very well documented. Here's just
a few references. There are more.
http://www.eham.net/ehamforum/smf/index.php/topic,72672.0.html
http://forums.qrz.com/archive/index.php/t-183159.html
http://forums.qrz.com/archive/index.php/t-230741.html
http://www.eham.net/ehamforum/smf/index.php?action=printpage;topic=2068.0
http://www.eham.net/ehamforum/smf/index.php?action=printpage;topic=2100.0
http://www.w8ji.com/vacuum_tubes_and_vaccum_tube_failures.htm
"The quickest way to ruin a 3-500Z, or other glass power grid tube, is to
never show anode color over a prolonged period of time! Storing a 3-500Z for
many years without operation almost guarantees a flash-over will occur at
the first application of high peak anode voltage. Gas, either from poor
manufacturing processing, out-gassing from elements, or seal leakage is the
primary failure mode of glass tubes."
73 Mike
www.w0btu.com
On Wed, Apr 13, 2011 at 2:36 PM, Rex Lint <rex@lint.mv.com> wrote:
> Not sure why you're so down on 220's - mine was old when I got it and has
> served for 20 years. Same tubes, puts out solid KW, easy to tune, no mods
> needed, except when I had Icom 751 I needed a relay to key it. Works fine
> with FT1000MP and K3. I WOULD like to make it QSK, but haven't had the
> guts
> yet. I'd like another for SO2R!
>
> -Rex-
>
> K1HI
> Rex Lint
> Merrimack, NH
> WWW.QRZ.COM/db/k1hi
>
>
>
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Mike Waters
> Sent: Wednesday, April 13, 2011 1:05 AM
> To: amps@contesting.com
> Subject: Re: [Amps] Which heathkit amp would you choose?
>
> If you decide to buy an SB-220, be warned that 3-500Zs that sit idle for
> years can go bad. Do yourself a favor and Google '3-500z gettering'.
>
> If you decide to buy either an SB-200 or SB-220, be aware that you will
> likely require the Harbach soft-key mod to prevent damage to your
> solid-state transceiver.
>
> 73 Mike
> www.w0btu.com
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
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