(16 June 2019)
Recently, I was able to acquire a
used Henry Radio 3002A amplifier for 144 MHz. This amplifier had been
in service at a repeater site for the Door County (Wisconsin) ARA in
the Sturgeon Bay area. For the last 11 years, it has been out of service and for the last 3 years has been in
storage in the garage of Howie K9HAH. On June 14, I took the Badger car
ferry across Lake Michigan to Manitowoc, WI to visit my mother, sister
and brother-in-law, who live in Manitowoc. My brother-in-law,
John, and I drove up to Sturgeon Bay and loaded up the 175 pound
amplifier in the back of my Jeep. After visiting more with my family, I
took the Badger back across Lake Michigan to Ludington and drove home
to Spring Lake, MI. Below, I have placed a few photos of the
amplifier and the low pass filter that came with it.
The front view of the beautiful Henry
supply area with the rear panel removed.
The inside of the RF deck showing the 8877 triode in the
notice the mouse nest under the blower. This has been
8877 closeup photo
I'm not sure why the
wirewound resistor in the lower left corner is not connected.
This is the filter that came
with the amplifier. It is a low pass filter with 0.66
dB insertion loss at 144 MHz, 0.8 dB I.L. at 148 MHz and about 28 dB I.L. at 210 MHz.
relay supplied with unit. Since this amp was normally used in a
repeater setup, there was no need for a Transmit/Receive relay.
I will continue to inspect and clean the
amplifier before trying to power it up. From the amplifier's
history, it looks like the airflow switch assembly was replaced in
1994. There is currently a waxed string attached to this switch.
I am wondering if the switch gets stuck in the open position from
time to time. Also the 16 mF 7.5 Kv capacitor was replaced in 1994. In
addition, the 90 second time delay relay and a wirewound 20k-ohm 100
watt bleeder resistor were replaced in 2004.
Roger Cox W8IO - Spring