[ETO_Alpha] Alpha 89 Question

[Paul Christensen]

> Other than that, my 89 has been very reliable - still running the
> original 1994 tubes which seem to be at full strength.  I use QSK almost
> all the time on CW and the PIN diode switching makes it completely silent.

Same here with a 20 year old Alpha 86.  Still using the original PIN diodes. 
Just finished a total cap replacement, including all electrolytics and 
tantalums.  Hopefully, it's good for another 20 years.

On an unrelated matter, I recently completed modification to the filament 
circuit of my Alpha 77Dx.  I've always detested grounding one side of the 
filament to chassis ground where the chassis forms the conductor return 
path.  In the case of the 77Sx, that's 20-amps of AC current flowing through 
the chassis.  It's not as much with the Alpha 86, but I wanted to elevate 
the filament above ground through a bifilar choke.  I also added Siemens Gas 
Discharge Tubes (GDT) on both sides of the filament to ground and cathode to 
ground.  The mod is 100% reversible in the event I sell the amp, but the new 
configuration now fully complies with Eimac's recommendations.

If I can fit a filament choke into the cabinet space of the 86, I plan on 
duplicating that effort.

Paul, W9AC