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Re: MFJ Relay, UHF use? (Was: Drake 2.4ghz convertor)

Hi Chris.
It is an electro-mechanical SPST relay driven by a simple rf-sense circuit.  Yes, it is probably an impedance bump, but should be of minimal concern since it is downstream of the active circuits in receive mode; i.e., the Drake is driving the coax with an amplified signal.  In fact, if you are using 50 Ohm coax, you are already at a mis-match since the Drake 2880 output is designed for 75 Ohms.  I plan to install one right before my 2 m preamp and the Drake unit and use the 2 m 9913F feeder to the shack.  If you wanted to avoid the relay in the circuit when you are transmitting on 2 m for mode J, you could put a coaxial relay in the line (ahead of the cheap relay) and have only the Drake in the line with the cheap RF-relay.
Jerry, K5OE

 "Christopher Cox" <cobox@urec.net> writes:
<< > Bill,
> You are likely not the only person to need this information over the next
few months.  It would be nice if you could share the "fix" with the BB. 
For those installing these, you might want to consider using an RF-sensed
relay, like the Ramsey RFC-1 (http://www.ramseyelectronics.com) to switch
the Drake in and out.  Use the same power you run for the Drake to power
the relay and buy a little protection.  They cost $14.95 for the kit.
> 73,
> Jerry, K5OE

I don't know. Have you used this kit? That relay looks like a heck of an
impedance dimple to me. What kind of relay is it?


Christopher Cox

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