Alpha Update: 1.5
So I was blessed by the radio Gods to obtain an ETO/Alpha 76PA from my father, N6SV. This amp has been stored for the better part of 25 years and was delivered a few weeks back when my parents drove north to help take care of me for a week after surgery. While I didn’t think I would get the linear amp this quickly, I was in a real hurry to connect it and get working with WPX quickly approaching.
Well, WPX came and went and I was still operating at 100w from the Yaesu FT-1000MP and the Alpha was sitting, looking pretty in my shack. I got in touch with Richard Byrd, who is a master when it comes to fixing Alpha amplifiers. I checked his site, N4UQ and started an e-mail conversation with him. I explained what I had, what I was trying to do and what his prognosis was.
Last week I dropped the Alpha at the local UPS Store, who packaged it and shipped it 3-day service for me. Thankfully the price was not all that bad, then again removing a 60 pound transformer sure helped. I figured I would let UPS package it because is there were shipping issues and it turned up broken I would hopefully have some recourse. But so far, brown did not fail me.
I received an e-mail from Dick today regarding the Alpha 76:
Steve;
I have your amp on the bench.The problem with the amp blowing fuses is likely related to the High Voltage capactor bank.They are a bit leaky (electrically speaking) and inconsistent from one to another. So I replaced the six caps and their equalizing resistors. As a precaution I will also replace the HV bypass capacitors with improved units. Your amp is an early model and has only four bypass capacitors.
I will install six of a slightly higher value. This will help protect the new HV filter caps from RF energy which can cause heating inside the electrolytic caps.
The drive configuration appears to be correct. I will know for sure when I test it.
I would like to install the PA current ‘meter doubler’ shunt. That will keep the meter from slamming off the scale at full output. There is no charge for that.
The ON-OFF switch is wired improperly. Many of these amps were configured this way.
It is simple re-wire of the switch assembly. But if left alone, the step-start circuitry can be damaged if both the ON and OFF switches are pressed at the same time.
Alpha fixed this oversight in later editions.I have noted you wish to change the input connector to a standard SO-239.
I’ll get these things done and we’ll test it out on each band for proper performance.
73, Dick
