[Lowfer] Amplifiers for 136 kHz

Wed, 21 Aug 2002 22:53:46 -0400

Mike

Hmmm...After all of the work Wild Bill has gone through optimizing conductors
for loop antennas, do you think he would give up 2.0 dB on cw by going to a
shack mounted linear amplifier? I can't say for sure but I'll bet he'd probably
rather cut off a pinky finger...or two... than lose a couple dB!

Jay

WE0H wrote:

> 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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