Good question!! I hope the answer appears on this reflector so all may see.
I never got around to getting an amp until after the new power limit was
effective, and then only got a 2x 572B amp. Looking "down the road", when I
might upgrade to a higher power amp, I will probably go for an older, 2KW
model, such as the L-7B or TL-922, for an increase of about 3 dB and add 160
meter capability. (Seems like the best dB/$ in lieu of the price of a
brand new amp. )
I know that the older amplifiers were marketed when the power limit in the
USA, for amateur use, was 1000 watts DC input, instead of 1500 watts PEP
output. And back then, one tuned the amplifier in reduced voltage mde (CW,
TUNE, however it is marked) for 1000 watts input (plate V x plate I). Then
switched to high voltage for SSB. This was supposed to result in still
having 1000 watts average, or DC, on SSB, but with much greater PEP. Hence,
2000W PEP input.
Given todays higher output power limits, can these pre - 1500W limit
amplifiers be tuned up in high voltage or SSB mode for c. 1300-1400 watts
out (whatever they will do, up to 1500 watts)?
Rick, WD8JJA
----- Original Message -----
From: "Thomas R. Williams" <n2cu@magtrol.com>
To: <amps@contesting.com>
Sent: Thursday, March 25, 2004 8:24 AM
Subject: [Amps] Re: Drake L7 newbie
Got the amplifier yesterday. What a beauty! I purchased it on eBay from
someone who advertised it as brand new, never used. It was exactly that. Not
a scratch or speck of dust anywhere, and the Eimac 3-500's looked like they
just came off the assembly line. Not bad for a 24 year old amp.
The L7 uses rather low plate voltage from what I read about in other
handbooks; 1760 V at 0.565 A. This works out to about 1 kW input power and
about 600 Watts output. I know this is the published rating for this
amplifier, but my little SB-201 puts out the same power with a pair of
572B's. I would think that the amp is capable of more, and the rating was
put on it to be conservative. In the SSB mode, the plate voltage is 2400 V.
Now for my questions. What are users of this amp typically running it at and
is 600 W output all I should expect on CW? Can higher voltage be used
without exceeding the ratings of the tubes or amp itself?
73,
Tom N2CU <><
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