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BACKWOODS RF Freq Counter Hookup

unit_399

EL CAPO
Jun 17, 2008
2,304
3,713
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ALEJANDRIA, COLOMBIA SA
I have a BACKWOODS RF freq counter for TRC-457 radio. I need the connection info. I believe the counter input goes to the VCO output, but not certain. Ralph made some fine gear before he passed.

-J.J. 399
 

Hey 399,

I might have some old info from Ralph around here.
I'll look tonight.

I think i remember Nomad talking about Ralph's novel way of feeding the counter on the 858 chassis, so he probably has some info about it.
LC
 
counter input goes to the VCO output,

Nope. Doesn't measure the VCO. It taps into the PLL chip's input pin. Counts the PLL chip's input frequency and does the math from there to display five digits of channel frequency. The need for only 5 digits becomes apparent when you turn the clarifier knob.

The display reading won't change. The clarifier's effect on your frequency is outside the PLL chip. The uPD858 gets the same input frequency fed into it no matter where you turn the clarifier knob.

It's a clever idea, and Ralph deserves credit for dreaming it up and writing the code.

Haven't seen anyone else try that trick.

73
 

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