I spent several years of my life as one of the "authorized" handful doing
77SX conversions. We had quite the assembly line running at one time.
My first SX arrived in three boxes. The big crate, the transformer and the
third was my first of many SX kits. I prided myself with the ability to
build an amp that looked as good as if it had come directly from the
factory. Why not? I'm a talented guy and the instructions for the first
conversion came in a hand written note included with the $500 parts kit.
"They" knew the second hole was going to be filled in at least 50% of those
amplifiers and that at $3000 for a 77DF in 1979-80 was way too expensive
without the ability for some sort of enhancement.
I quickly dealt with mismatched tubes, an under designed power supply,
severe complications on 160, 10 meter tank heating and a host of other
issues.
I fixed them one by one.
Some of you may have seen some of my deluxe Alpha 77DD converted units with
matchingly painted 4500V floor console power supplies?
Once we souped up the power supplies all the other weak links reared their
ugly heads including the ALC Overshoot issues of almost every PREMIUM ham
rig on the market at that time.... The 100 Watters were never an issue, but
wheel in a 240 watt Signal One CX-11 and watch your amp leave the room.
All the weak links led me to the preliminary design of my own from the
ground up 77DD that could handle anything but a severe ALC overshoot in the
HP position. I finally scrapped the development of that box and stepped up
to single more durable tubes/hardware.
Finally I received a stern warning "Phone Call" from Saint Paul in 1984-5,
who's inspector had personally ran one of my converted units at a customer's
site over a bottle of Tanqueray Gin and a night of heavy 40 meter DXing....
Just to wake me up he also included, it was time to shimmy my portly ass up
my Bertha Pole and repaint it.
That pretty well dashed my future aspiration of replacing Bill Brown as the
"God of MOJO Amplifierdom"
Now I pretty much spend my days "Freeballing" while reading what you big
guns have to say. :-)
Sincerely,
BOB DD
"Years ago the Alpha 77Dx was manufactured with one 8877 tube and a square
plate that could be removed to add a second 8877, making a 77Sx...."
Yes, I own one with the plate still intact. Back in the early '90s, I was
also considering the purchase of the 87A as an alternative to the 77Dx.
While talking to Ray one day, he conveyed all those issues, including 160M
inefficiencies which may have gone to the point of the doorknob caps.
Anyway, after my discussion, I was convinced that it was just a trick to
foster new hardware sales. There's more money to be made on the sale of a
new amp than in the sale of some parts. But there seems to be some truth to
his assertion, although I'm still happy with the 77Dx purchase some 15+
years later.
For several reasons, I've never considered adding the second 8877 to the
amp. For one, I would much rather troubleshoot an amp with one tube, versus
two.
Paul, W9AC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|