Who knows, Al? I have the failed 3-500ZG here in the shack - keep thinking
I'll make a table lamp out of it, ha! The only indication on it is a "QC"
stamp of some sort on the phenolic base that has a Roman "12" on it and an
indistinguishable character above that. It's marked "112" on the top in
magic marker, probably for matching up pairs. Otherwise, I have no clue
about it. I don't think anything I've contributed on the topic is going to
help because it was 10-12 years ago and probably not relevant any longer.
If EIMAC's are not able to be found (I'm sure NOS are gone by now) then it's
just academic anyway.
73, Duane
Duane Calvin, AC5AA
Austin, Texas
www.ac5aa.com
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Al Gulseth
Sent: Monday, August 11, 2014 7:08 PM
To: tentec@contesting.com; ac5aa@ac5aa.com
Subject: Re: [TenTec] Hercules 444 amp
Duane (or any of the other "Wizards of the 3-500Z"),
What was the manufacture date or other identifying info on the tubes in
question? As you may recall, I recently asked for advice on checking out a
stored 3-500Z for a local ham friend of mine. (We haven't gotten to the
project yet - we need to rustle up a dummy load to borrow that will handle
the amp's output properly for the test. Neither of us has a suitable load.)
My feeling is that if the spare (I don't know the brand) is of suspect
manufacture, I'm less inclined to risk damage to the amp testing it.
Actually, it would be interesting to see a list of which brands and vintages
are preferred, and which should be avoided.
TNX/73, Al
On Mon August 11 2014 12:23:42 pm Duane Calvin wrote:
> I did - that's why I mentioned that there seemed to ba a rash of failures
> around the same time with the RF Parts 3-500ZG's. They were currently
> advertising to indicate they were "better" than the Taylor branded tube
> made in China, but as a number of us discovered, there seemed to be a
> "production problem" (I'll call it, to be kind) that we all felt. I don't
> know how the later tubes fared because the person I sold the amp to stored
> it in a closet with a lot of other ham gear he intended to put on the air
> some day. I think he eventually sold it all, so I have lost track of it.
> Not a big deal at this point, but the common wisdom at the time was to
find
> EIMAC's, if you could, as they were a lot more reliable. That could be
> completely upside down now, especially since EIMAC's are probably scarce
as
> hens teeth.
>
> 73, Duane
>
> Duane Calvin, AC5AA
> Austin, Texas
> www.ac5aa.com
>
>
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Rick -
> DJ0IP / NJ0IP
> Sent: Monday, August 11, 2014 7:07 AM
> To: 'Discussion of Ten-Tec Equipment'
> Subject: Re: [TenTec] Hercules 444 amp
>
> Duane, even if things were in best order, all products from all companies
> still have occasional premature failures and somebody is always the proud
> owner. Perhaps you just had bad luck, unless you heard of a lot of
similar
> cases.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Duane
> Calvin
> Sent: Monday, August 11, 2014 1:33 PM
> To: George Fritkin; Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] Hercules 444 amp
>
> I don't think we're talking power out, but rather long-term reliability.
At
> the time I had the two pairs of RF Parts 3-500ZG's they were touting how
> they had the factory running to meet their manufacturing criteria. They
> had done a lot of work to improve the factory's product to meet their
> requirements. Maybe this is all old news now.
>
> 73, Duane
>
> Duane Calvin
> Sent from my iPhone
>
> > On Aug 11, 2014, at 12:41 AM, George Fritkin via TenTec
>
> <tentec@contesting.com> wrote:
> > 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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> >>
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