On Jul 7, 2004, at 6:50 AM, Joe Isabella wrote:
Hi Roger!!
I've been running "Rice Box" AM for some time now, and the trick is to
keep the drive below the point that rig distorts. I know that all the
manuals say "40W on AM", but I've found that power level includes more
distortion than I like to see. If you keep it down below 25W you'll
be in great shape. In fact, I've talked to a few guys running the 756
series into an amp and they sound pretty good!
Indeed, Joe, when run properly (at a 4 to 1 ratio), low-level
modulated, linear-amplified AM has way less audible distortion that
traditional plate-modulated AM.
The only caveat to this is that the amp must also be kept below it's
maximum PEP level, too. If you use the 30L-1, that's 1000W PEP or
APPROXIMATELY 250W carrier on AM. You'd do well to reduce the 756's
output to keep it down to around 200-225W or so. I used to drive a
Kenwood TL-922 at about 250-300W carrier and it seemed quite happy at
that level. I now have a Henry 3K-A, and it will easily go above the
APPROXIMATE "legal limit" of 375W carrier on AM. I would bet your
30S-1 is similar in this regard.. I simply reduce the drive until I
see around that level and all is well. In case you haven't caught on
yet, the "rule of thumb" is power out in PEP is approximately equal to
AM carrier x4. It totally depends on the audio (sideband) levels
coming from the exciter. I hope I'm not insulting you with
oversimplified statements!! Feel free to contact me off-line if you
want to discuss this more. BTW, I now run a Ten-Tec Jupiter with my
Henry for an all made in the USA shac
k. I
guess you could call it a "Wheat Box" instead (??). :-)
Also, I live a little north of you in the DFW area, so we could easily
setup a sked if you like. I currently have my shack disassembled, but
it will be back up by the weekend.
Best of luck and 73!!
Joe, N3JI
Lewisville, TX
Roger Agnew <k1kq@motorhomesusa.com> wrote:
I would like to get on an AM Net tomorrow with my Icom 756 Pro driving
my Collins 30S-1 or 30L-1. Does anyone know or could guide me to a
source of information to properly drive these amps with the Icom 756
Pro.
Roger Agnew
K1KQ - Austin, TX
888-536-5500
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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