[600MRG] Amp

Pat Hamel pehamel at cableone.net
Mon Aug 3 08:20:29 CDT 2015


Jim and all,
I ran a tube-type linear on 600 meters which was the "book" 30 percent
efficient.
The 811's were grid-driven and easily neutralized. I got 300 watts out of
them and that gave me 15 watts ERP based on measuring my high-loss city lot
total resistance. (with buildings, lack of radials, and trees as supports).
There are many ways to get to five watts ERP (EIRP), I chose to use the 1930
era approach "just for grins". 

Don't forget the low-pass filter at the antenna. It will help receiving and
keep you out of the neighbor's AM radio. (944KC & 1416KC). <www.500kc.com>

W5JGV has a remote reading ammeter design <www.w5jgv.com> I copied that
works well. The toroid can be obtained as a sample.

I was hoping to finish DXCC and be back on 600 meters by last winter,
possibly this winter...... Cambodia only works RTTY & I can't type..........

Pat W5THT & WD2XSH/6
(Mississippi Gulf Coast) grid EM50ki



-----Original Message-----
From: 600MRG [mailto:600mrg-bounces at w7ekb.com] On Behalf Of Jim Miller
Sent: Sunday, August 02, 2015 8:11 PM
To: 600mrg at w7ekb.com group
Subject: [600MRG] Amp

Now that the K3 is getting closer to being a 630 capable machine and the
FCC is lumbering toward a band decision I'm thinking more about an amp. I'm
assuming the market is too small for an Elecraft offering.

The K3 puts out 1mW on the transverter output. I'm assuming that I'll need
50-100w to get to 5w ERP.

Assuming 100w for a minute and assuming 10-15db for the final amp stage
then you only need 5-10w before then. That should mean that even with poor
efficiency not a lot of power will be dissipated until the finals. That
means that I could keep the chain to that point linear and make the output
stage decision based on what modes are most prevalent.

I assume CW for historical reasons and JTXX for practical reasons, WSPR as
well. Not sure about PSK or other modes which would require a more linear
final.

So I could build a 1mW to 10W linear then wait and see about the finals.

Thoughts?

73

jim ab3cv
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