I recently acquired a Johnson Signal Sentry and just got it installed in the station today.? Thought I'd pass along a few notes on the subject.? First, the Signal Sentry is a tube device with no power supply and is designed to get its plate and filament supply from the associated transmitter.? If your transmitter doesn't offer an external connector for those voltages, you'll have to provide a separate supply.? My Ranger has the octal connector on the rear panel and I thought I could easily use that for the power, but, I discovered the Ranger octal socket is NINE pin and not 8 pin.? Nine pin octal plugs and companion shell are a bit pricey these days, but available on eBay.?
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Second, the Sentry uses RF sensing with a jack on the back to connect to a single wire to pickup the signal.? Johnson recommends that if your antenna is coax fed, you scrape away the shield in a small area and wrap the sensing wire over that hole to pick up the signal.? I didn't like that, but found that the probe jack on the Johnson TR Switch is the perfect RF source.? Just bare the end of the pickup wire and plug into the jack.
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The sidetone frequency generated by my Signal Sentry was much too high for my liking.? I substituted a 6.7 megohm resistor for the stock 2.2 meg R10 and that brought the sidetone down a few hundred cycles.? Or, you could change the value of C6.? On the schematic, R10 is listed as 1 meg, but was actually 2.2 meg in my unit.? The resultant sidetone starts with a click and the instructions warn you about that.? There's also a slight chirp, which isn't present in the Rangers output.??
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If you're using a receiver like a 75A-4, you're better off just monitoring your signal with the receiver.? If you're using something like a Hammarlund HQ-170, it's BFO gets pulled by your strong signal and the Sentry sidetone would be very useful.? Haven't tried the phone monitor function of the Sentry yet.
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73, Floyd - K8AC
Floyd - K8AC