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Show all reviews of the ALPHA 78
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of the ALPHA 78.
Sep 25, 2013 12:57
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Time owned: more than 12 months
I worked at ETO in the late 70's when we built these amps and never thought I could afford one.
I was lucky enough to buy this amp from a local for parts due to the soft 8874s, and was able to purchase a pair of 3CPX800A7s from a YCCC buddy.
I asked Gary, our Twin Cities repair whiz to do the upgrade, as well as the low drive mod.
Result: Shockingly amazing performance. 1500+++ on all bands with 33w of drive and 30ma of grid current. Easy no tune 80-10, and 17M is a dial up on the manual 15M position.
When I worked at ETO, we always thought that the iron core transformers in the 76 series were better than the Hypersil due to lower voltage drop with the iron core transformer, and I was concerned doing the mod with the Hypersil. However, it just worked fine and did what it was supposed to do. Voltage+current = output.
I'm more impressed now than I was 30 years ago with the architecture for this box. No component arcing issues, even though the output can be way more than the design parameters. The Hypersil transformer just works. I use the higher voltage SSB position, which seems to be a good place for the 3CPX800A7s.
I was always worried about the 8874s even though everybody said that they were strong tubes. 30 years on a 8874 with a replacement cost of $800 each from Richardson? With the 3CPX800A7s, I don't have to worry any more.
Would I like an auto bandswitched amp? Of course! However, for much less than $2K invested in QRO, I'll reach over and change the bandswitch!
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