[RVRC] Cross post: Dsrc Digest, Vol 82, Issue 3

[drew Moore]

-----Original Message-----
From: dsrc-bounces at lists.epiphanydesign.net
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Sent: Wednesday, July 04, 2012 4:02 PM
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Today's Topics:

   1. Yaesu FT-817 Measurements (RTMercuri)
   2. Re: Yaesu FT-817 Measurements (K2PAT at ARRL.Net)


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Message: 1
Date: Tue, 03 Jul 2012 18:58:47 -0400
From: RTMercuri <notable at mindspring.com>
To: dsrc at lists.epiphanydesign.net
Subject: [Dsrc] Yaesu FT-817 Measurements
Message-ID: <4FF37927.7030702 at mindspring.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi folks,

I know a lot of us in the David Sarnoff Radio Club own or have used the
Yaesu FT-817. It's a great little radio and serves us very well with our
low-power activities especially on Field Day. At Field Day this year, Ray
WA2PYX, who was operating at my station as he has done in prior years, was
wondering if I was really getting 5W output, since the SWR meter on my
antenna tuner indicated considerably less. He generously offered that I
could stop by his lab at Princeton Instruments to do some experimentation
and take a few readings. We discovered the following facts:

- Indeed, the radio does consistently output a solid 5W, even when the
Voltage applied to the unit is considerably less than 12V. When operating on
external power, the radio shuts off when the voltage goes below around 7.5,
but even at the fringe level, or even when the transmit key drags the
voltage down 1-2 volts, the radio is still reliably outputting 5W.
Similarly, if the voltage is slightly above 12V, the output is still 5W. It
seems that the radio is perfectly designed to output 5W and it does that
very well. Note that the maximum that it can handle is 15V -- and here's a
nice article about creating an input voltage conditioner, that gives some
additional insight into specs, for the FT-817:
http://www.ad5x.com/images/Articles/Condx817RevA.pdf

- Another experiment that we tried involved the use of a straight-line
connection between the radio and the 12V battery, using a cigarette-lighter
style plug and my (fully charged) car starter battery (that I had purchased
on sale with rebate at Pep Boys for $35, normally $89). What we learned was
that the Yaesu-supplied cigarette-lighter power cord does actually cause a
drop of about 1/2 volt as opposed to the straight-line connection. This may
be because of some limiters in the Yaesu plug component (we didn't take it
apart to see). Again, as long as the voltage is sufficient to keep the radio
operating, the output is still 5W.

There is also a detailed webpage that provides info about battery
modifications and issues for the FT-817 here: 
http://www.ka7oei.com/ft817_batt.html

Hopefully this discussion makes sense and sheds some light on questions that
we have wondered about. Especially -- as the battery drains down during FD
are we not getting responses because we are not putting out 5W or is it just
because more people are on the air and we are getting drowned out? Now we
know we are putting out 5W, so using a fresh battery will probably not help
at all!

In summary, the FT-817 is a fairly rugged, compact, and very reliable
multiband QRP rig. Though it is a tad on the expensive side (around $650
new, $500+ eBay), and you really should buy or download one of the
cheat-sheets (such as: 
http://www.ko4bb.com/Manuals/Yaesu/Yaesu_FT-817-cheat_sheet.pdf) or booklets
to help figure out (or remember) how to program it (especially since the
user manual that comes with it does have some errors), the unit does the job
and keeps on putting out 5W under a variety of conditions!

Feel free to share more thoughts about the FT-817 if you have any (or if
there are any corrections to the above commentary, please note).

73 and Have a Glorious 4th, all!
Rebecca KA3IAX.