[Lowfer] Amplifiers for 136 kHz

Wed, 21 Aug 2002 21:28:44 -0500

Just build the shack and loop amps linear and the feedline will be fine, but
then why not just build the shack amp as the final amp and not go outside. I
would think that the loop would be broad enough for a skinny 136kc band.

Mike>WE0H
http://www.we0h.us/lf.html

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Bill Ashlock
Sent: Wednesday, August 21, 2002 5:52 PM
To: [email protected]
Subject: Re: [Lowfer] Amplifiers for 136 kHz

John A,

> >One, a small high-efficiency switching amp located out in the
> > woods, just like I have now, but with TO-220 transistors (maybe
> > MJE15028/30?) mounted to a plate for heat sinking.
>
>Why handicap yourself by putting an amp out in the woods? Wouldn't >life be
>simpler to keep the active stuff inside?
>
Haven't figured out a way to drive a 100ft coax with a square wave having an
impedance near 0 ohms, unless I use a tuned circuit between the final and
the coax to convert the output Z to 50 or 70 ohms. But that makes it two
circuits to tune rather than one each time I want to change frequency. Any
ideas?

Don't see too much of a handicap with an untuned final in the woods (well,
not counting the loop tuning cap). Takes < 2 minutes each way to run out and
bring in the final box to the bench to make alterations and then return it.
I have a loop simulator coil and exciter simulator on the bench so there's
no surprises when I re-connect it back to the loop and shack cables.

Bill

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