[TMC] SBE use on 80 meters

[John Vendely]

Hey Nick,

I see no reason why you couldn't set the VMO for low-side injection 
throughout the entire 80M band.  Dropping the VMO down to 1/2 the 
high-side injection frequency, and switching in the doubler would 
degrade frequency stability in addition to being a nuisance...

73,

John K9WT

On 2/3/2012 12:11 PM, Nick England wrote:
> Hi gang - if you have a TMC VOX (VMO Variable Master Oscillator), how
> do you use your SBE to cover 80 meters?
>
> The VMO covers 2000-4000 kc and gets mixed with the 270kc sideband
> signal in the SBE (SBE-2, -3). Normally the VMO is set 270kc higher
> than the desired output frequency and the lower mixer product (VMO
> -270) is tuned for amplification. For desired outputs of 3730-4000 kc,
> the VMO is set 270kc lower and the upper mixer product is tuned
> (VMO+270) - and the sidebands are reversed of course.
>
> I have an SBE-9 which has a 250kc local osc - the manual blithely says
> tune the VMO from 2000-4250 kc for output frequencies 1750-4000 kc,
> with no mention of the flip-flop as in the earlier SBE manual. But my
> VMO don't tune up to 4250 (unless I double from 2125). This would be a
> major PITA when moving from below to above 3750kc (not just retuning,
> but turning the VMO dial about 15,000 turns).
>
> So, with that background, does anyone see any reason I can't just
> cover the whole 80 meter band by tuning the VMO from 3250-3750 and
> always tuning to the high side of the mixer product? Yeah the
> sidebands are flipped and the MF tuning dial will be off, but so what.
>
> And yeah, I know I could just hook up my HP signal generator and
> forget about the VOX, but what's the fun in that? The whole point of
> TMC-ness is Heavy Metal and lots of it!
> http://www.navy-radio.com/misc/shack.htm
>
> cheers,
> Nick K4NYW
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