[ARC5] 75 Mtr to "Q-5er" Converter.

[David Stinson]

I've been asked a couple of times about this simple converter 
which can be used to receive 75 meters (or any other band)
on your little 200-400 KC aircraft "Range" sets:

http://home.netcom.com/~arc5/converter.JPG

The operative word is "simple," and I find the trade-offs 
for keeping it so acceptable.  Not even slightly interested in 
building something for the bridge of the Starship Enterprise
because it might be 13.725% "better" ;-)

I used a color-burst crystal (3580 KC as in the diagram)
because they are cheap and plentiful.
3880 KC will appear at 300 KC on the dial.
However- there will be images from the 3.2 MC SWBC
stations lower in the band.    I don't worry about this
because I'm only going to use the rig from 3870-3890 anyway.
You can add a "wave trap," which is just copies of  
L1's secondary and C1 in series with the antenna lead, 
which you tune to reject the SWBC.

If you have a crystal in the 4180 KC range, the image 
freqs will be in 4480 KC area, which should be quieter.

Open the power lead to the converter during transmit
and your TR switching for these little rigs is done,
unless you're running a KW.  Might want to protect 
the input to the chip if you do that.

Remember that most of these "Range" receivers 
have very sharp IFs, which can restrict recovery
of speech sidebands ( meaning "sound crummy" ;-)
Often, one can "stagger-tune" the IFs- tune the 
first a little low, the middle right on, the last a 
little high- trading some gain for more bandwidth.
There are other ways.  If using a BC-453, just push
all the little "sticks" on the top of the IF cans all the way in.

Back to work for me,
73 Dave AB5S