[R-390] modified R390A

[Bob Camp]

Hi

Grab a TCXO from out of a scrap cell phone to drive your solid state  
readout and it will be at least as stable as the radio. The  
frequencies they use are reasonable for processor clocks.

Bob

On Jun 21, 2008, at 7:46 PM, Flowertime01 at wmconnect.com wrote:

> Jay,
>
> Did you find the R390/A receiver drifted,or was it the read out that  
> drifted.
>
> The read out would have had a time base crystal for what was  
> essentially a
> frequency counter.
>
> The counter would have summed the VFO, and LO plus 455Khz and  
> provided a
> display.
>
> Back in 1974, 75 the goal was to get a counter that would do 50MHz  
> in TTL
> logic for under $100.00. It was a "73 Magazine" type project.
>
> My 1968 military version had Nixie readouts and filled a 19" rack with
> "repairable" logic chips. I remember when we got Texas Instrument  
> logic chips to
> repopulate the wire wrap back plane with these new little black  
> chips in 1970.
>
> There were several versions of digital readouts built for the R390/A.
>
> Most were several hundred dollars back then and done mostly for the  
> WOW
> factor.
>
> Today you use a micro processor chip and a surplus LCD display.
>
> The receiver is still rock solid and the display counter drifts as  
> much as
> every because the processor crystal is just not very stable.
>
> Roger AI4NI
>
> Waiting for field day
>
>
>   </HTML>
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