[Elecraft] Elecraft Digest, Vol 49, Issue 52

[WILLIS COOKE]

I think that you have the answer to the riddle Ian.  9
megacycle filters were not available until about 1960
with the second generation of transceivers.  By the
time of Galaxy 3 and 5, NCX-5, Swan 350, etc the need
for the USB/LSB selection was passed, but we stayed
with the tradition.

I have seen some remarks that would indicate that the
Elecraft is unique in being able to select the
sideband, but I have not had a transceiver that would
not.  Even back to the Hammarlund HX-50, if I remember
correctly one could select the sideband.  I know on
the two transceivers I have in the shack, Kwd TS-850
and Yaesu FT-900 when you select SSB it puts you on
the preferred sideband, but if you press the button
again it puts you on the other sideband.

Cookie, K5EWJ

--- Ian White GM3SEK <gm3sek at ifwtech.co.uk> wrote:

> WILLIS COOKE wrote:
> >It does not give the same sideband on 80 and 20. 
> You also have to 
> >consider that the rotation of the tuning capacitor
> of the VFO turns the 
> >opposite direction for 20 as it does  for 80.
> 
> The direction of tuning is not what inverts the
> sideband.
> 
> The only thing that inverts the sideband is if the
> SSB frequency is 
> subtracted in the mixing process. So:
> 
> 9MHz USB + 5MHz VFO = 14MHz USB
> 
> 9MHz USB - 5MHz VFO = 4MHz USB - sideband is not
> inverted.
> 
> But in Norgaard's 'New Approach to SBB Generation'
> in QST, June 1948, 
> the SSB is generated on 5MHz and the VFO is around
> 9MHz, so:
> 
> 9MHz VFO + 5MHz USB = 14MHz USB
> 
> 9MHz VFO minus 5MHz USB = 4MHz **LSB** - now the
> sideband is inverted.
> 
> If anyone is still in doubt about this, words aren't
> going to help any 
> more. Please take a few minutes with a pencil and a
> calculator, punch in 
> some numbers and verify it for yourself.
> 
> 
> -- 
> 
> 73 from Ian GM3SEK         'In Practice' columnist
> for RadCom (RSGB)
> http://www.ifwtech.co.uk/g3sek
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Willis 'Cookie' Cooke 
K5EWJ