My AL-80A is S/N 095, purchased 1 Jan 1986. It has the QSK-5 installed
and, before that, had the older PIN-5 QSK switch, that finally bit the
dust. I've modified the PS to be a FW bridge at 4 kV B+ so it runs only
on 240 VAC. It still has the original 3-500Z in it and I have a spare.
That mod required that I build a new PS in it and, because it changed
the output impedance, alter the Pi-L output circuit for more inductance
on 80 and 160 m in particular (I had to make a bigger toroidal inductor
for 160 m). I added a bit to 40 m, too.
It's currently on the shelf because I got an AL-1200 for a good price,
added a QSK-5 switch to it, replaced the filter capacitors (added
another capacitor) and bleeder resistors and changed the HV PS to be 4
kV (I'm a B+ junkie). Under full load, B+ is about 3.6 kV, up about 900
V from the original design. The AL-80A is a very nice amp and stone
simple inside and the 3-500Z is extremely tough. At the higher B+ it
sings very nicely and is much easier to drive, though the total output
only increased by about 100-200 W, depending on the band.
Kim N5OP
On 8/10/2014 3:11 PM, Rick - DJ0IP / NJ0IP wrote:
I support your opinion, Wade.
My old AL-80A is only 28 years old, but has been used HARD in at least 20 or
30 big 48 hour contests. When I wasn't using it, it was loaned out to
others who were. It is on its original 3-500zg tube and its output power
has only dropped about 100w per band.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Wade Staggs
Sent: Sunday, August 10, 2014 7:54 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Hercules 444 amp
*At least for now, even if we could afford one of the Big Gun Solid State
Amps. I would hope that we would have the good sense to stick with an Amp
which runs 1 or 2 of the 3-500ZG Triodes. They are as tough as Nails. How
can you argue with a system that with proper care, will run a lifetime. The
tubes in our SB-220 are Original. This means that they are approaching their
Fortieth Birthday. We recently replaced the Capacitors and Relay. The Amp
was still working Great when we did this Preventative Maintenance. And Even
a Cave Man with Knives and Bear Skins can repair the Amp if needed. *
* 73
from Wade/KJ4WS*
On Sun, Aug 10, 2014 at 12:01 PM, Robert <rmcgraw@blomand.net> wrote:
Many to most design parameters do change radically when converting
from BIPOLAR to MOSFET devices.
I seen to think MFJ does have their products in the reach of the
average ham. I find typically they offer reasonable designs,
reasonable quality at reasonable prices. Maybe it's the hams average reach
that needs adjusting.
The days of the SB-200 and SB-220 KIT prices are long gone.
Good quality amps, those that are clean and don't spew garbage across
the bands, require good design and good quality parts. Then add a
high duty cycle and it places more demand on the designs and the parts
choices.
73
Bob K4TAX
Sent from my iPhone
On Aug 9, 2014, at 5:38 PM, Brian Carling <bcarling@cfl.rr.com> wrote:
So maybe the Hercules can be converted to use MOSFETs. Seems like it
should be possible.
I also think MFJ needs some competition on MOSFET linear amplifiers
to
get the price point within reach of the average ham.
There is just not a good reason why so many linear amplifiers should
cost $3500 to $9500 when you look at the parts cost and manufacturing
cost.
[/SOAPBOX]
Best regards - Bry Carling
On Aug 9, 2014, at 5:24 PM, Douglas <sparks06524@yahoo.com> wrote:
Date: Sat, 9 Aug 2014 10:12:45 -0400
From: Brian Carling <bcarling@cfl.rr.com>
To: "k9yc@arrl.net" <k9yc@arrl.net>, Discussion of Ten-Tec
Equipment
<tentec@contesting.com>
Subject: Re: [TenTec] Hercules 444 amp
Message-ID: <86F80EE5-1044-42AA-9641-D8859123467B@cfl.rr.com>
Content-Type: text/plain;
charset=us-ascii
Seems like a lot of RF power transistors are similar, so it should
not be too difficult to find a substitute.
Best regards - Bry Carling
------------------------------------------------------------
Ah - but it is hard to find a substitute. The Ten-Tec factory
can't
find one.
There were only a few designs of 250 to 300 watt 50V bi-polar power
transistors made. The remaining ones are hard to get and have an HFE
that is too high. Several such transistors have been totally discontinued.
Motorola for example is out of that business. M/AComm bought some of
their designs but in general bi-polar RF transistors are considered
passe. RF MOSFETS are now the name of the game.
Per another poster: I've not had trouble with the power supply
drifting
upward with temperature rise. Perhaps they solved that with compensation.
73,
Doug/WA1TUT
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--
Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)
/"In theory there is no difference between theory and practice. But, in
practice, there is." //-- Attributed to many people; it's so true that
it doesn't matter who said it./
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