External RX port for Kenwood TS-480

I added an external RX port to my TS-480 for a SDR receiver which is used as a band scope.
The ext RX port is buffered with high input impedance emitter follower so it is not affecting the TS-480 receive performance.


External RX port with a bulkhead female SMA connector. I used a ready made coax cable with the SMA connector.


Snap-shot of TS-480 schematics. The emitter follower is sampling the RF signal going to TS-480 RX.
Note that Kenwood has made a mistake in the schematics. Antenna 2 is selected when TS-480 is OFF.



Quick and dirty construction.
The blue capacitor is the 1n input capacitor. Brownish ones are 100n
caps.
The red wire is +13.8V which is available although TS-480 is switched OFF.



Update 2017-01-29 OH7SV


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