Date: Tue, 3 Oct 2017 16:39:00 -0700
From: Jim Brown <jim@audiosystemsgroup.com>
To: amps@contesting.com
Subject: Re: [Amps] Alpha
On 10/3/2017 2:27 PM, Richard Solomon wrote:
> ps: I usually buy a new radio every
> 6 or 7 years and a new Amp every 10.
Some of us can afford to do that. It took me 60 years in ham radio to be
able afford a USED 87A. Before that, it was USED Ten Tec Titans.
The virtues of the 87A for my application are PIN diode QSK, auto-recall
of tunings, and auto-retune (AlphaMax). Last I looked, current
production Alpha products use vacuum relays, which are unacceptable to
me because they wear out pretty fast when used for serious QSK
contesting. That's why I replaced the Titans, which also use vacuum relays.
73, Jim K9YC
## I dont buy a new gas furnace nor a new fridge or stove every 6 years. I
fully
expect them to run for at least 25+ years, and be a work horse. Meanwhile,
the SB-220, L4B, etc, will be fully functioning long after the processor,
now unobtainium in amps that use them. You can stuff anything from
3-400Z, 3-500Z, 4-400A /B/C, etc into a SB-220, etc.
## What is the life expectancy of a gigavac, or kilovac or jennings
vac relay, when used in QSK mode ?? I heard it was something like
10-12 years, with main focus on CW qsk contesting. I may well be wrong.
Years ago, alpha switched from jennings to kilovac..since the kilovac had more
robust internals.
The Gigavac GH-1 is even better..and typ hi pot tests to 7.5 kv...right outa
the box.
Pretty easy to speed up a vac relay..even if you are voltage limited. Kilovac
engineers
told me years ago on the phone, that if you are voltage limited, to use the 12
vdc version,
instead of the 26.5 vdc version. Gigavac offers both a 12 and a 26.5 vdc
version.
24-30 vdc will easily make a 12 vdc vac relay operate blazing fast.
## A small cap can also be wired in parallel with the series drop resistor...
to speed it up even further.
Thats called a ..RC hot shot circuit and is old news. But you can only go so
big on the cap, depending
on the initial overvoltage applied. I believe there is an upper CW speed
limit with vac relays...I think it
was in the region of 20-30 wpm. If thats the case, the sped up vac relay may
not suit high speed cw ops,
like the 30-45 wpm ops.
## I know several folks with 87-As..and none have ever had an issue with the
oem PIN diode TR setup.
However, I also know a few folks with the manual tune 89, that have had PIN
diode issues, and had to
replace them. Why the pin diodes were more failure prone on the 89 and not
the 87-A is still a mystery.
Im assuming the failures were enough, such that Alpha decided to revert back
to vac relays.
Jim VE7RF
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