A couple of years ago I decided to replace the Eimacs in my SB220 after all
they were the original tubes. I carefully measured power out. We were going
to San Diego so on the way I picked up a new pair at RF parts. I got home
installed the new tubes. Guess what, with new tubes.........exactly same power
out
Oh, we'll
George, W6GF
Sent from my iPad
> On Aug 10, 2014, at 6:51 PM, "Duane Calvin" <ac5aa1@gmail.com> wrote:
>
> Sure, Carter. My Centurion came new with two RF Parts 3-500ZG's. This was
> fairly early in the life of this tube configuration (graphite anode variety)
> and manufacturer, and TT had just started advertising they were using them.
> After about 2 years of occasional use, generally running between 600-900W
> (and all settings well within the safe zone), one of the original tubes
> developed the infamous grid/cathode short. I replaced the original tubes
> with a new matched-pair of 3-500ZG's from RF Parts, and shortly after that I
> sold the amp (with a used spare tube). I know lots of guys who have had
> Heath and other amps with EIMAC 3-500Z's in them for years with very few
> problems. Yes, mine could have been a late early life failure, but at that
> time I was reading of others having similar problems with these tubes. That
> was a few years ago - maybe RF Parts has improved their relationship with
> the factory that makes these tubes and all is well today. So, my "data"
> consists of one in-person experience along with a number of other reported
> failures around the same time, for whatever that's worth. The implication,
> to me, is that the tubes at that time were not of the same quality level as
> EIMAC's.
>
> 73, Duane
>
>
> Duane Calvin, AC5AA
> Austin, Texas
> www.ac5aa.com
>
>
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Carter
> Sent: Sunday, August 10, 2014 8:33 PM
> To: tentec@contesting.com
> Subject: Re: [TenTec] Hercules 444 amp
>
>> On 8/10/2014 2:08 PM, Duane Calvin wrote:
>> This was certainly true of the EIMAC tubes, as long as you cared well
>> for them. I've not had as good a luck with the current
>> Chinese-sourced tubes (specifically, the 3-500ZG's from RF Parts,
>> which the Centurion uses.)
>
> My Centurion (which I obtained used 20 years ago) finally had one of its
> tubes [rather spectacularly] go to the great beyond.
>
> Unless I get really lucky and find a NOS pair at the e-place, it seems
> like my only other option is a matched pair from RF Parts.
>
> Could you please elaborate a bit on your statement above that says "I've
> not had as good a luck with the current
> Chinese-sourced tubes (specifically, the 3-500ZG's from RF Parts)".
>
> 73,
> Carter K8VT
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