There are a few of the early Collins 208U-10's in the hands of radio amateurs...
10 - 12 kW PEP or CW, with IM3 at least 36 dB down from one tone, assumíng a
very good exciter and
correctly adjusted RF NFB.
The 208U-10A or HF-8022 (>15 kW PEP, power supply limited)
are also in amateur hands, and I know of at least two owners in Sweden
(both have lent my ex-Air Force manual set for copying...).
Nowadays, after that amateur radio has been deregulated in Sweden, it has most
probably
become quite safe from a legal point-of-view to run such power levels, as long
as no EMC related interference
or out-of-band operations are present.
The power limits in the current Swedish amateur radio rules are quite vaguely
worded,
and there are no legal means of revoking an amateur radio license any longer.
Incidentally, the mu of 4.5 stated in the Eimac data sheet refers to the screen
grid to control grid amplification factor,
which is quite unrelated to amplifier RF power gain. It is however of some
interest when dimensioning bias supplies and networks.
The power gain of a grounded cathode tetrode amplifier in class AB1 can be
extemely high, only limited by
the transit time and grid circuit losses, but practical considerations usually
limits the usable power gain to 100 or 20 dB. If RF NFB is used, the gain may
be further reduced.
Hence the proliferation of parallel 4CX350A's in class A as drivers for
4CX10000 and 4CX15000's.
73/
Karl-Arne
SM0AOM
----- Original Message -----
From: "Jan Erik Holm" <sm2ekm@telia.com>
Cc: <amps@contesting.com>
Sent: Sunday, July 02, 2006 5:55 PM
Subject: Re: [Amps] 4CX10 000J
> surely no ham would use a thing like that, or?
>
> / Jim SM2EKM
> ----------------
>
> Peter Voelpel wrote:
>
> > All the J-types are low distortion, gain of both is about 20db
> >
> > 73
> > Peter, DF3KV
> >
> > -----Original Message-----
> > From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> > Behalf Of Joe Subich, W4TV
> > What are the differences between the 4CX1000J and 4CX10000D -
> > particularly to explain the 10 KW vs. 15 KW output difference
> > in the "normal operation" figures on the Eimac short form
> > catalog (www.cpii.com/eimac)? Of course, with a listed gain
> > of 4.5, it would seem to take 2500 W or so to drive either of
> > them to their full capability ...
> >
>
>
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