"Eric Fairbank" wrote:

Where did you hear that myth??? Iv'e been a marine electronics tech
for 30
years and have never heard that one. I know what you stated is total bs
but
just for drill I did a little test before leaving work today. Hooked up
a
variable power supply to my Icom 735 with a Bird 4381 power analyst in
line
(which reads PEP directly). I also verified the wattmeter readings using
an
o-scope. The power didn't start to drop til the voltage dropped below
10.5v
and I was able to receive just fine all the way down to 9.5v. Below that
the
rig started to die.

Eric

"Bruce in Alaska" wrote in message
...
It is commonly understood that for each volt dropped from 13.6 VDC
at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
the internal Voltage Regulators drop out of regulation and the
radio goes OFF.



It is not a Myth, is is a Fact, and as others have stated, your
experiment doesn't prove, or disprove the fact. Also, as Larry
stated the 21st Century Icom Rigs have a lot more headroom in the
SolidState Amps than just about any other Marine MF/HF Radio,
just to deal with this cause. Just try your experiment with ANY
SGC designed and built radio.

Bruce in alaska I am Old School, and an Old Fart, and I do remember
back in the Old Days, before Autotuners, allowed
anyone to think they were World Class Radiomen...
--
Oh, my gosh, it's just killing me to sit here without jumping in! Then
when I heard SGC mentioned, I knew that someone besides me had experienced
"Bruce's Law". I am compelled to defend his position and scientific
observations without reservation.

How much midnight oil I've spent working on the DC supply system on
"commercial" vessels, trying to reduce the voltage drop. Until the "code"
made batterys in the pilot house almost mandatory, can't you imagine running
an SGC711 from engine room batterys? Here's a typical example (it is a
genuine "commercial", by the way) of a vessel still using this one time
popular rig:

http://www.alaskaboat.com/sn033.htm

Those SGC711's were hard to coax to even 75 watts PEP with any wire
less than #4 if you were more than two feet away from the battery! (OK,
stretching a little here) And the built-in wire antenna tuner was a charmer,
hey? But as the URL and dozens more can show, that not everyone has yet to
install an Icom M802.

Some earlier SEA's and Icom's with first generation digital VCO tuning
were cool, too. A sneeze or laugh in the mic was as apt to change channels
as anything if the antenna was fed directly from the radio, and some joker
installed #10 wire for DC power!

Early automatic antenna tuners were (are) cool, too. A little pitching
and rolling in the North Pacific and they would lock up and refuse to even
try to tune anymore. Then the transmitter's fabulous SWR power foldback
circuit hit the fan and 5 to 10 watts could be used to heat up the tuner's
coils and capacitors. (condensers, actually)

Lots of this early stuff is still out there. By the thousands. Modern
marine SSB radios certainly have improved their ability to survive poor
installations, but is that any reason to go as cheap as possible with DC
wiring and antenna installations? (RF ground on "Tupperware" boats is
probably just as important, but I digress)

Old Chief Lynn

(besides, tubes help heat the pilothouse and ease aching joints)