[Amps] Alpha

[Jim Thomson]

Date: Tue, 3 Oct 2017 16:39:00 -0700
From: Jim Brown <jim at audiosystemsgroup.com>
To: amps at 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