On Fri, 28 Mar 1997 07:57:03 -0800 Merit W6NQ <rfp@rfparts.com> writes:
>A few comments to clear up confusion on the manufacturing status of
>3-500Z & 3-500ZG tubes.
SNIP
>Svetlana does not manufacture 3-500Z or 3-500G/ZG in Russia. I have
>seen a few CHINESE tubes with the "Made in Russia" stamp on them. One
>assumes this was done in error by local warehouse types while silk
>screening p/n & logo, etc.
That is a very generous statement which translates into English as FRAUD.
Once is an error, twice is a coincidence, etc...............
>Some talk has been made over production of a 600W dissipation tube
>using a larger metal plate (Svetlana 3-600Z). This is still in the
>thinking stages, as no production is scheduled at this time. Obtaining
>additional emission without increasing filament current is still the
>limitation on power. However, Graphite tubes (3-500ZG) can be
>considered as having 600W plates. (This may help those tired of
>blistering metal plate tubes.) Other than dissipation, the "ZG" tubes
>have same tube characteristics as the standard "Z" version.
I have to disagree a bit with the above. The standard Eimac or clone
tantalum plate tube has a published amplification factor of 130. The
Amperex graphite version has an amplification factor of 200 according to
their 1969 spec sheet. It is for that reason that Amperex tubes have been
known to take off in such marginally stable amps as the SB-220, TL-922,
AL-82 and maybe a few others. ( I have heard of a later spec sheet with a
lower amp factor but have not seen it.) They work just fine in the
L-4B, various Henry's and others that were originally designed and
shipped with Eimac 3-400Z's which coincidentally have a 200 amplification
factor.
If memory serves me, the very first TL-922's had Amperex tubes since they
were cheaper then. Instability problems forced Kenwood to go back to
Eimac's which are what they used for development.
I have yet to see any Chinese specs that dont change by the week. I am
"assuming" that they copied the Amperex for their graphite offerings
since design does not appear to be their forte.
Another factor which appears to need continuous stressing is that
graphite 3-500's are not the proper replacement in some amps that have
poor airflow. Graphite tubes are not generally meant to show color since
doing so can cause internal poisioning. I was told this by an Amperex rep
many years ago and also by Mr XXX ( Mr XXX simply because I forgot to
write down his name) at Eimac about 3-4 years ago which was before they
introduced their version.
I realize that there has been maybe one person talking about new process
technology to eliminate this problem. But with so many brands of graphite
tubes on the market I really must remain skeptical; at least until I see
it in writing from the tube manufacturer ONLY (spec sheet,
advertisement, etc). Blather and hype from amp manufacturers and
distributors is only good until you try for a warranty replacement.
Just my 33 1/2 cents worth.....2 cents aint worth squat no more.
73...Carl KM1H
>
>At 09:50 AM 3/27/97 -0500, you wrote:
>>I have a SB-1000 that I recently bought. It has all of the paperwork,
>>etc. I have used it a total of 2 to 3 hours maximum.
>>I have read here that the 3-500Z's are supposed to be no longer made
>by
>>Eimac, and are being made by Svetlana.
>>Is there any "updates" or mods to this amp? I know that the ameritron
>>AL-80A is supposed to be a "clone" of this amp.
>>Just curious, as I am comtemplating going to another amp that will do
>>the 1500w output.
>>Thanks for your replies.
>>
>> DE KC4TBH
>>
>>--
>>FAQ on WWW: http://www.contesting.com/ampfaq.html
>>Submissions: amps@contesting.com
>>Administrative requests: amps-REQUEST@contesting.com
>>Problems: owner-amps@contesting.com
>>Sponsored by: Akorn Access, Inc. & N4VJ / K4AAA
>>
>>
>Merit W6NQ/W6NLO
>
>
>
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampfaq.html
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|