[Elecraft] K3: CW feature request

[Ron D'Eau Claire]

I think that's because the story's gotten confused. Much SSB was generated
using low-frequency xtal filters (in the 455 kHz and below) range and
heterodyned into the HF range. Images were a serious problem at higher
frequencies. 

I believe the popular 1950's surplus conversion for 75/20 meter SSB
generated the SSB signal at 5 MHz. Then it was heterodyned with a 9 MHz VFO
to produce output on 75M or 20M. Having the VFO above one band and below the
other inverts the sidebands, putting the USB on 20M and LSB on 75M.

This was all long before the popular 9 MHz crystal filters became available.


The problem with O.T. memories is that they aren't always complete. 

Now where did I put my shoes last night....?

Ron AC7AC

-----Original Message-----


On Wed, 2009-12-02 at 21:06 -0800, Alan Bloom wrote:
 I've heard people say that many times over the years but clearly it's
> not true.  A 9 MHz IF set up for (let's say) USB will still be USB no
> matter whether you add or subtract the 5-5.5 MHz VFO.

I just did a little Googling on the Internet (AC6V.com and elsewhere)
and discovered to my astonishment that this is an actual bona-fide
controversial subject among radio amateurs.  Despite the fact that a
simple 2-minute back-of-the-envelope calculation is all it takes to
disprove the myth.  For the record:

Intermediate frequency:
Carrier   9.000 MHz
Sideband  9.001 MHz
==> USB

Add 5 MHz VFO:
Carrier   9.000 + 5.000 = 14.000 MHz
Sideband  9.001 + 5.000 = 14.001 MHz
==> USB

Subtract 5 MHz VFO:
Carrier   9.000 - 5.000 = 4.000 MHz
Sideband  9.001 - 5.000 = 4.001 MHz
==> USB

I can't believe people are actually arguing about this!

Al N1AL


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