[R-390] modified R390A

[Flowertime01 at wmconnect.com]

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


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