[Lowfer] Amplifiers for 136 kHz

Wed, 21 Aug 2002 23:19:54 -0500

Why would he loose a couple of DB by using a feedline on 136kc??? The amp
and antenna will work just like any other amateur band amp and antenna.
Match the output of the amp to the feedline and the antenna to the feedline
and hokus pokus, the feedline, amp and antenna are happy. A guy could run a
motor tuned circuit out at the antenna to peak the resonance of the antenna
if they wanted it to be perfect across the 136kc band. The amp is just going
to have a lowpass filter that is designed to present 50-ohm output impedance
to the feedline across a certain bandwidth that the builder will select
which of course will be the whole 136kc amateur band. I don't see where
anything is going to be different than any of the other amateur bands with
the equipment we run currently. Am I missing something??? This just seems so
simple. On another note, the caps are in the mail for you Bill, thanks much.

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

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Jay Rusgrove
Sent: Wednesday, August 21, 2002 9:54 PM
To: [email protected]
Subject: Re: [Lowfer] Amplifiers for 136 kHz

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