Joel,
That's a real concern on filaments as well. My utility line voltage runs
about 252 VAC. On my Alpha 77Dx, I ended up installing a bifilar filament
choke, even through the cathode and filament are not tied together (e.g.,
Ameritron AL-500). The older Alphas were designed in an era when utility
voltage was about 5% less than the present.
Two benefits of the choke: (1) I was able to get 10A of filament return
current completely off the chassis; and (2) more importantly, there's enough
ESR in the choke to drop the filament voltage from 5.5V down to 5.0 VAC,
right on target for an 8877.
Paul, W9AC
----- Original Message -----
From: "Joel Kornreich" <k2qbv@hotmail.com>
To: <amps@contesting.com>
Sent: Sunday, November 14, 2010 7:34 PM
Subject: [Amps] Replacement of Collins bulbs in the 30S-1 amplifier (and
other Collins)
>
> Noticed a couple of comments concerning bulbs in radio equipment. I have
> a 30S-1 Collins amplifier and for a long time, I kept blowing out the dial
> and two meters on the 30S-1 front panel. If one remembers, these Collins
> radios were designed around 110 volts. In todays society radios are
> coming out with 120 volts. Anyway, I changed all the pilot bulbs in my
> Collins from the #47 to #51 bulb which is 7.5 volts. The higher voltage to
> my amplifier pushes the 6 volts up just a little and bulbs are gone. Also
> changed the K201 step-start relay to 115 volts inplace of the standard
> 1960s 110 volts. I'm sure this will help a few people owning Collins from
> 50 years ago. Joel, K2QBV
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> Amps@contesting.com
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