Bulletins from the Pacific Packet Radio Society - page 049

conditions and the only failures have been in the Antenna Relay which wasn't designed for continuous service anyways. One of our Packet Radio people, Ted Baleshta has developed a PIN diode switcher for the relay and the units are being used in PR service in Montreal and Ottawa. This in no way disputes the K6HWJ input - it merely reflects our experience. A message from you to Ted might get him to write up the mods for the PIN diode. Regards

de Larry VE3QB

FILE QST.82.04.l5.0.W2FPY

Hank -

Although the FM-21 is not considered a "clean" rig, I do disagree with the statement that they are not useable by other than RF experts. There are a good many in use in NJ which have survived the years.

As I stated previously, the FM-21 is not suitable for service as a repeater. It suffers from oscillator stability problems. It is however a very serviceable rig for use on a single channel indoors.

The FM-21s coming from Clegg will DEFINITELY require tune up! If you feel that this factor will prevent a number of your users from getting them on the air, please say so. We intend to have a 'tune up' party here in NJ to get all our units on the air.

As far as finals blowing out, the manual states that the output is protected against infinite SWR. After looking at the schematic, I must disagree with the manual; the final transistor could be cooked by running 'key-down' for a while into an open or shorted line. I tried a little experiment with mine. I ran it for 30 minutes straight, into a 50 ohm dummy load. Power out was 12 watts. The final and heat sink was VERY warm after this maneuver, but you COULD hold your hand on it. I then tried to run it into an open line (251 of RG8). This operation REALLY heated the final rapidly. The final transistor was too hot to hold my hand on, after only three minutes. However, nothing burned out!

Do you anticipate sending packets as long as 3 minutes into an open or shorted line? Do you anticipate sending packets as long as 30 minutes into a proper load? Aren't we really talking about a very low duty cycle? ---- Point made?

73, Steve

ps: Do you still want the FM21s, or should I cancel? - S


Dear Hank,

In re : AMICON Interim Standard

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