I've been out of town for a few days and have just now read this note as
well as the ones who are pretty sure it is an alternator problem as well as
those who have it occurring at other instances.
I have one of the original TM-D700's and for many years operated it off of a
12 volt supply from my house. The antenna was outside on the roof and ever
so often my radio would have the squeal sound. I never heard it from the
speaker but my friends would get in the habit of asking me if I was stepping
on my cat's tail knowing that I had two cats in the radio room. One of my
other friends bought two of the radio's and had one in his car and one in
his house. The one in his house did the same thing but the one in his car
never had a problem. We called Kenwood at the time and they could heard of
the problem. We then both sent our radio's in and their service dept said
the radio's worked fine and they could not replicate the problem.
We gave up on it and just got used to the 'teasing' about the cat tail
sounds. It is NOT an alternator whine unless you had a bad alternator in a
race car as the sound increases in frequency so fast, it would have to be a
fast reving engine under no load. Our whine went up in frequency and I
notice David indicated his while was decreasing in frequency.
Anyhow, one person wrote in that he noticed the problem when the supply
voltage got low. I now think this is closer to the cause of the problem
coupled with a temperature problem as the radio is getting warmed up. At
the time the power supplies we were using were conventional series regulator
supplies and they were characteristically 12.0 volts output. Nowadays, the
'12 Volt' switching supplies are all set to 13.6 volts output. In addition,
I know my radio room was always cool as it was on the ground floor and under
the desk by the wall. It did not always make the noise but it was more
typically when it was first used for the day.
73's all
Jim K5QQ
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of David Jordan
Sent: Wednesday, October 29, 2008 10:01 AM
To: rfi@contesting.com
Subject: [RFI] Kenwood TM-D700
Hi folks,
This one is a bit odd. My buddy has a Ford F-150 and installed in the truck
is his TM-D700 dual band VHD/UHF radio. We chat during our drive into work
in the mornings.
Almost without fail when he is transmitting at least once during the 30 min.
drive I will hear what sounds like a siren on his audio Whrrrrrrrrrrr
starting at a high pitch and slowly going down in audio tone freq. He has
grounded the radio, etc., yet the weird noise continues to occur. Last week
I installed a TM-D700 in my Ford Sport Trac and guess what - now he says I
have the same odd occurrence of the erratic whine syndrome.
My radio is also grounded extensively as I run 1KW on 75 and 40m.
Thoughts and recommendations welcome.
73,
Dave
Wa3gin
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