[TenTec] Centurion and AM

[Bob McGraw - K4TAX]

Ever see a  Continental AM Broadcast transmitter?  In some of the models you 
will find the last stage to be a big linear amplifier.  Of course those were 
used long ago when we weren't worried about heat or the electric bill.

Centurion inefficient??? It's output is about 1000 to 1200 watts PEP with an 
input of about 2300 watts.  That's about 54% or so.  The Omni VII runs about 
40% efficient on SSB at 100 watts PEP.  Even my 1 KW class C AM transmitter, 
being pair of 4-400's modulated by a pair of 4-400's will have a PA 
efficiency of about 65%.

Don't knock linear amplifiers in terms of efficiency.   The secret to a 
clean AM signal is to use a linear amplifier that is indeed "linear". 
Proper tuning along with correct drive is the key to this success.    The 
nay sayers of course will say otherwise.

Remember, it takes a bit of cherry color on the plates to burn the gas out 
of the envelope.  It is actually good for the tubes.

73
Bob, K4TAX






----- Original Message ----- 
From: <bcarling at cfl.rr.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Friday, August 01, 2014 10:02 PM
Subject: Re: [TenTec] Centurion and AM


>I tune my Centurion 422 with enough drive for 1 KW out.
>
> Then I feed it about 20 - 25 watts of carrier and start modulating. 
> Currently using the OMNI
> VII.   DON'T overdrive it!   Keep an eye on the plates and let them only 
> glow a little. You don't
> want them melting!  Your mileage may vary.
>
> You will get lectured by the purists on how "terribly inefficient" this 
> is, but if it works I don't
> knock it!
>
> Bry, AF4K
>
> On 1 Aug 2014 at 20:59, Timothy Johnston wrote:
>
>> I would be feeding it with 25w of AM from a TS-590. So.. exactly what 
>> would
>> the safe procedure be?
>>
>> 73 de Tj, K4TFJ ...
>>
>>
>> On Fri, Aug 1, 2014 at 8:46 PM, Barry N1EU <barry.n1eu at gmail.com> wrote:
>>
>> > On Sat, Aug 2, 2014 at 12:28 AM, george fritkin via TenTec <
>> > tentec at contesting.com> wrote:
>> >
>> > > 200 to 250 watts AM results in 800 to 1000 watts PEP at 100% 
>> > > modulation.
>> > > Three 811 tubes can not handle that power.
>> > >
>> >
>> > How about two 3-500Z's?
>> >
>> > 73, Barry N1EU
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