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

[Ian Wilson]

Very handy, Dave, thank you.

However, I seem to recall that the range sets that I have don't have a BFO.
So the
converter would allow AM reception only.

e.g. BC1206 schematic: http://www.freeinfosociety.com/media.php?id=5038

You could add a tunable 75m oscillator to your converter to act as a BFO.
It would need to be tuned to 262kHz (if that is the BC-1206 IF) away from
the
station being received, but would be simple and would require no mods to the
beacon RX.

73, ian K3IMW


On Wed, Dec 26, 2012 at 7:10 AM, David Stinson <arc5 at ix.netcom.com> wrote:

> 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<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
>
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