[R-390] The radio machine...

[Norm n3ykf]

After I hit send, the depth of the rabbit hole became obvious.

Been thinking about feeding the IF input to an SDR. All of the
difficult RF/filtering stuff is done for you.

This eliminates the Collins filters as the skirts are steep. Back
panel IF out on the 390a is electrically behind the IF filters. Using
a SA as a panadaptor shows JUST how steep they are.

Run the SDR with GPSDO. (overkill by orders of magnitude )

Currently living in Old Fart Land. All seem to sold off the BA's prior
to moving. (FL) BORING!!!!!!!





On Fri, Apr 15, 2016 at 4:30 PM, Nick England <navy.radio at gmail.com> wrote:
> You can combine both R-390 and precision oscillator interests - several
> models of Navy transmitters have a VFO that uses a Collins PTO with a
> motor-driven AFC capacitor to lock it to an internal or external frequency
> standard. About 3 orders of magnitude better stability than a stock PTO with
> the internal standard (Bliley 100kc crystal/oven).
> http://www.navy-radio.com/xmtrs/frt5/O91-operation.JPG
>
> No reason you couldn't have a receiver with this scheme but I don't know of
> one offhand. Maybe I'll hook up my VFO to an R-390A some day....it'll only
> add another 29 tubes.....
> http://www.navy-radio.com/xmtrs/frt5/o91-104.jpg
>
> Cheers,
> Nick England K4NYW
> www.navy-radio.com
>
> On Fri, Apr 15, 2016 at 3:50 PM, Norm n3ykf <normanlizeth at gmail.com> wrote:
>>
>> It started with the idea of precision oscillators. Think R-390A.
>> Crystal controlled, fully tracking, final IF variable (PTO). What
>> makes something like that work? Took 3 blue stripers and made one good
>> unit. Still have parts for one more. The WHY of how it worked
>> fascinated me.
>>
>