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Digital frequency readout for HQ 170




 
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Author Topic: Digital frequency readout for HQ 170  (Read 551 times)
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ns7h
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« on: April 05, 2018, 08:22:33 AM »

Anyone install an outboard digital frequency readout on an HQ 170 or characteristically similar receiver?  I have one of the inexpensive counters found online and it works very well with an inexpensive signal generator for alignment, but it would be very helpful to be able to easily see an accurate reading when tuning to preset AM or SSB frequencies using the HQ 170.  I can program offsets for IF. 

I will figure it out eventually -  I have been into the receiver for alignment and a few upgrades and repairs and can work around a schematic and the circuitry, but hope someone has an example of a successful application of these useful and inexpensive counters.

Thanks, Bob NS7H
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KB5MD
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« Reply #1 on: April 05, 2018, 02:51:00 PM »

Run a wire from the counter input to the receiver oscillator tube and wrap it around the tube 3 or 4 turns and you should get a reading on the counter.  Then set the counter for the proper i f offset.  I have both an AR88 and a SP600
done this way.
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w9jsw
Two shots of Whisky
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« Reply #2 on: April 05, 2018, 08:23:08 PM »

Sometimes those cheepo counters do not have a very good front-end. Almost TTL levels. I have a FET circuit I added to one of those that seems to work really well. Here is a link..

https://forums.qrz.com/index.php?threads/inexpensive-frequency-counter.576863/page-7

John
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ns7h
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« Reply #3 on: April 05, 2018, 08:46:17 PM »

I will try the inductive link (no wire changes) to the tube and see what happens.  I do have the counter connected to an unused port on my antenna switch to capture RF leakage across the switch from the transmitters (IC 7600 and Heath Apache) and it works really well but likely a stronger RF signal than the coil on the oscillator.  However, I still want the receiver frequency and will try the simple solution first.  I understand that any direct link to a circuit may need some buffering.  I also should look at the documentation on the EZM counter to see what buffering may be needed. 

Thanks for your replies.  Again, the community is there for me.

NS7H
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ns7h
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« Reply #4 on: April 05, 2018, 11:29:34 PM »

loosely coupling the frequency meter and a 455 khz offset provided the accurate reading I needed and the signal was sufficient to drive the meter.  As measured with a ic 7600 and with the 100 khz onboard calibrator provides a very good indication and response.  Thanks to all....

The frequency meter is the 1-75 Mhz ezm electronics studio circuit board and has been a very good tool for the money.

NS7H
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