[RFI] Kenwood TM-D700

WA3GIN wa3gin at comcast.net
Sat Nov 1 08:42:25 EDT 2008

Does anyone have a variable 12dc supply that they could use with the D700 
and perform some testing with voltages from 13.8 down to 11.8.  I know the 
FT-857 I have doesn't like any voltage below 12vdc.

I also discovered a filter application rated at 35 amps that is really a 
voltage regulator. This unit would solve any concerns about low voltage and 
it claims to eliminate alternator whine, etc. Sort of nice that it solves 
both problems. Go here for details http://radioproshop.com/filters/ns50.htm


----- Original Message ----- 
From: "Jim Baremore" <Jim.Baremore at mchsi.com>
To: <rfi at contesting.com>
Sent: Thursday, October 30, 2008 9:53 PM
Subject: Re: [RFI] Kenwood TM-D700

> 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 at contesting.com [mailto:rfi-bounces at contesting.com] On
> Behalf Of David Jordan
> Sent: Wednesday, October 29, 2008 10:01 AM
> To: rfi at 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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