[AMPS] Amplifier for CW

[Roy Koeppe]

Hi Vic,

I see you're displaced too. I'm from Tulare, just down the road.  Here I
can't find my mike either. Two amps here operate with just a trickle of
idling current, about 10 ma. Have true pi-net inputs on cathodes, grounded
grids. One amp uses a pair of 3-500Zs with 3 kv on plates. I find operating
between class B and AB-2 is a good compromise for efficiency, drive
requirement, maintaining wave shape, etc. The input pi-net adjusts better
with some idling current.

I leave the amp pulled up in "XMIT" at all times and switch the antenna with
PIN diodes for silent  QSK. The other amp uses 572Bs and has similiar bias
class, but also has an auto-bias circuit which cuts off all plate current
during key-up.

Just some thoughts; 73,

Roy   K6XK   Iowa    outback

Roy and Joy Koeppe
P.O. Box 43
Rolfe, IA  50581
712 848-3253
royanjoy@ncn.net


"Simplicity is Ingenuity"





-----Original Message-----
From: Vic Rosenthal <rakefet@rakefet.com>
To: Amps reflector <amps@contesting.com>
Date: Saturday, February 13, 1999 5:07 PM
Subject: [AMPS] Amplifier for CW


>
>OK, even though I have a perfectly good working amplifier, reading about
all
>these building projects has made me decide that I want to build one too.
Here's
>my question: I'm a CW operator.  I got a mike with my transceiver, but I
can't
>find it.  Given this, I'd like to design my amp from the start for CW only.
>
>My thought was to set the no-signal bias high enough to cut off the plate
>current completely.  Then the operating point would be a little past
class-B.
>As long as the bias is not high enough to start sharpening up the keying,
why
>should I care about IMD?  This would give me more efficiency and simplify
the
>circuitry.
>
>Any comments or other suggestions?  I'm also open to suggestions for choice
of
>tube (preferable) or tubes.  I'd like to get between 1000 and 1500 watts CW
>output.  Price is a big factor!
>
>73,
>Vic, K2VCO
>Fresno CA
>
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>


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