77Sx Wattmeter Module
While discussing the purchase of my 77Sx with the previous owner he told me the wattmeter module was not working and had been removed from the amp. He also told me he would send it along with the amp. I intended to repair it and put it back in. Well, the module was NOT with the amp when it arrived and the Deadbeat Son of a Bitch never sent it.
What to do? I called Alpha and Dick
Byrd to see if they had a module I could purchase. No joy. Can you
believe nobody stocks new wattmeter modules for 77s? HI HI
I also posted a message on the ETO/Alpha Amp reflector asking if there was one
around anywhere. I got a response from Tom, N0SS asking what happened to
the one in the amp and why I needed to replace it. I explained the
situation to him and said I was going to etch a new board if I could not find
one. He said he frequently etched PC boards and was set up to do it.
I had already removed the module from my other 77 and had begun to make drawing
to use in etching a board. Here are some pictures of the project from
beginning to end. If anyone should ever need a PC board I've got several
spares. Just email me.
Click on thumbnail for larger picture.
Front of original module
Rear of original module
Rear trace drawing. From original board
Front trace drawing. From original board
Trace drawing overlaid with picture of original board
First trace drawings from N0SS
Final revision of drawings
Front of etched boards
Rear of etched boards
Front of new wattmeter module with components installed
Rear of new wattmeter module with components installed
New module installed in 77Sx. It works great and calibration is within 5% of my Bird 43
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Created: November 3, 2005
June 15, 2013
© Copyright 2007, PakRatz, Corpus Christi, Texas, USA