[Lowfer] Another worthwhile project at " XR "

[Andy - KU4XR]

Greetings again all:

After obtaining a couple of torroid cores, I wound them with
#24 enameled wire to 63 uH each, and put .018 uF to ground
between them. All nicely mounted on a small solder pad board.
First time I've ever wound a torroid before and by gollies, it
don't look to bad. hi-hi.  I had been using a couple of 
Radio Shack 100 uH chokes de-wound to 63 uH. They worked just
fine, as a matter of fact, there was no difference in output
between the chokes and the torroids. So I thought; well that
was a lot of winding for nothing.... AAAAHHHHH ( buzzer sound ).
The improvement turned out not in output, but Harmonic reduction.
With the chokes my signal meter on a short wire read 30dB over 
S-9; the 2nd harmonic ( 370.600 KHz ) would drop down to 
S 1-1/2 . A very good reduction. the 3rd harmonic ( 555.900 KHz )
had no S-Meter reading, but was clearly audible. When I went
to the Torroid filter; I was surprised at the difference.
The 2nd harmonic all but disappeared, and I had to turn the 
volume up to hear it. The 3rd harmonic : NIL ! So all the 
winding was worthwhile when I looked for what it was intended 
to do.

Next: *** A simple transistor switch. I couldn't believe it at
first. I have been using the popular 2N2907A / 2N2222A pair.
I had read that there was a better pair, and recommended.
The MPS-6602 / MPS-6652 pair. A friend gave me a couple to 
try out and I have to admit, there is no comparison between 
the 2 sets of transistors. When I switched, The PA voltage 
went down from 26.8 to 25 Volts drawing 40 mAmps for exactly 
1 Watt, BUT !! My RF current went up an extra 5 mAmps with 
the new pair. Lower voltage - same current - higher output.
I don't know about anyone else but I call that an improvement.
And, if you plan to replace transistors, or are building a
transmitter; I also recommend the MPS - 6602 / 6652 pair.
They definitely are better.

On to the next project now; ( which is bedtime right now )

73 everybody, and happy lowFER-ing  ::::



Andy - KU4XR - EM75xr - Friendsville, TN.
LOWfer Beacon " XR " @ 185.29866 KHz ( QRSS-60 )
Coordinates:  N:  35* 43' 54" - W:  84* 3' 16"
http://www.myspace.com/beaconxr