[captainclock1988]

Thanks, I was thinking I would use a 1N4007 Diode in place of the old Selenium.

It doesn't give any voltages in the manual but the selenium rectifier that's in the unit isn't very big so more than likely a 1N4007 Diode will work fine in there and won't requiire too much voltage dropping.

This thing does have a Dedicated RF Ouput which means that I should be able to hook up a frequency counter to this thing no problem the RF Output according to the specs  is capable of outputing in excess of 100,000 microvolts which should be no problems for a frequency counter.