[HBR] [Glowbugs] Quartz Crystal Oscillator

[Bill Cromwell]

On Wed, 2011-08-03 at 14:37 -0400, John Landrigan wrote:
> How practical is this device (Russian tube type quartz crystal oscillator) to use in place of a FT-243 quartz crystal as the second oscillator for a 50 KHz 2nd IF in an HBR styled receiver?
> Ebay # 260829157003
> 
> I was hoping to procure a wiring diagram and then put a capacitor in series to adjust from the 59 KHz to the 50 KHz IF frequency.
> 
> John KA4RXP and Jody KG4VES
> 
> 

Hi John,

Others have already pointed out the limits of rubberizing crystal
oscillators. For some perspective, at BFO frequencies for 3.395 mc I.F
strips (and filters) separate crystals are used for USB, LSB, and CW in
the rigs I have here because a single crystal does not want to 'stretch'
that far (about 3 kc or so) at those frequencies. Some radios with 9 mc
I.F. do rubber the crystal for USB, LSB, and CW. Some radios and filters
do not require a separate CW carrier. At 9 mc apparently we can more
reliably get the 3kc or so (up to 5 kc) that is required by switching
the "rubberizing" elements.

I have used the 455kc L-C free running oscillators as BFO in a tube
based Hammarlund and now in a Ten Tec receiver that is otherwise crystal
and PLL controlled. There are two BFO settings that are interactive,
touchy to align, and are switch selected for sideband (and USB or LSB
can be programmed). I much preferred the variable BFO on the Hammarlund
to the binary choice on the Ten Tec (but that isn't programmable). At
455 kc there is negligible warmup drift on the tubed radio and not even
noticeable on the Ten Tec. At 50 kc the stability from turn-on should be
even better. I agree with the suggestion to use a variable L-C
free-running BFO. If you really are talking about a mixer closer to the
antenna from a higher frequency you probably wouldn't be talking about a
59 kc oscillator.

73,

Bill  KU8H