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Author Topic: Kenwood TS-50s Noise Blanker problems  (Read 5682 times)

Posts: 448

« on: December 20, 2010, 07:09:47 PM »

I have been running a Kenwood TS-50s in a 2007 Kenworth diesel rig for the last several months.
The problem I am experiencing is an ineffective/non-existent noise blanker. The truck's diesel engine
uses electronic fuel injectors and they generate pulsing noise on HF (all bands) similar to spark plug
ignition noise. Switching the Noise Blanker in or out makes no difference.
   I have bonded everything I can (with permission from the truck owner) using 1" braid and also put
ferrite beads (from DX Engineering) on as many cables as I can and still no difference. I can disconnect
the coax from the Auto Tuner I use (LDG Z-11 PRO) and the noise goes completely away. So, I know it's
being picked up via the antenna/coax.
  I bought an ICOM 7000 mobile rig with the intention of putting it in the truck since I had talked to some
other hams who were truckers, that said the Noise Blanker and other filtering in the 7000 would get of
the pulsing noise. (they had the same noise in their rigs) I installed it temporarily and just as they said
using just the Noise Blanker (and with some slight adjustment) the noise goes completely away and I can
still hear stations I wish to talk with. The problem is, the ICOM looks brand new! And I just cannot make
myself install the radio in the big truck permanently. I'm almost certain that the rough ride (we do oilfield work) would destroy the ICOM. So, it's sitting in the shack here at home.
  I was wondering if anyone had ever tried to adjust the noise blanker in the TS-50s in the presence of the actual noise source? According to the service manual, it has two adjustments and on the work bench, you are supposed to use a noise generator to adjust it. I plan to try it and if that doesn't work, I am thinking
about getting one of the DSP speakers to see if that helps. Has anyone ever tried using one to get rid of
ignition noise? None of the advertisements I've read for the different external(and some internal add-on)
DSP units ever mention removal of pulsing noise like ignition noise/fuel injector noise.  
Other than the fuel injector noise, the TS-50s works fine in the big truck. No one on the receive end
hears anything from the injectors, so at least it's not getting into the transmitted audio.
Thanks for any and all suggestions!

Posts: 10248


« Reply #1 on: December 21, 2010, 07:14:25 AM »

Install the Icom. I know of one OTR driver who has put over 1 million miles on a 7000, and it is still going strong. All of the components are surface mounted, and compared to the TS50, much less prone to vibration. It has survived, and so will the Icom.

You didn't ask, but part of the problem is the use of the auto coupler. And, I'd bet there is still a fair amount of common mode, even though you have used ferrites hither and yon. if you're like most truckers, you've mounted the antenna in the worst possible way by using the mirror mounting bracket which affords almost no ground plane. As a result, the coax is as much of an antenna as the antenna is, so you end up hearing more RFI than you would otherwise.

How close am I?


Posts: 448

« Reply #2 on: December 21, 2010, 05:34:58 PM »

Alan, close but no cigar!!  Grin
  The only mirror mounted antenna I have is for the "required" CB radio in my truck.
(required on jobsites and rock crushers, otherwise I wouldn't have it as the antennas get
beat to pieces by tree limbs since so much of our work is off road)
  The antenna I am using is a 102" whip with the LDG Z-11 PRO auto tuner. The whip is
mounted about 3 feet behind the cab ( a 2007 Kenworth Day Cab) which has very little metal
in it. (the entire cab, other than portions of the doors is made of an extremely strong plastic)
 I can disconnect the coax from the auto tuner or even the radio itself and the noise goes away.
So, yes, it is coming in thru the antenna system.
Also, the trailer I'm using is a belly dump which has a slope to the rear of the truck. The antenna
is about 3 1/2 to 4 feet forward of the trailer, mounted on a bracket between the frame members.
I understand that that setup is not an ideal situation but, it does work. Just the noise is bad.
I might go ahead and use the 7000 as you suggested, but, the reason I hesitate is because
our operations are 30 to 40% off road. (oilfield roads) Very rough since we build the actual well sites
in some pretty hard to get to places. ( oil and gas companies are crazy, they'll drill ANYWHERE)
  I guess if the surface mounted components in the 7000 are considered tougher than the build
of the TS-50s, then I should give it a try.  I did not buy the 7000 new, but, when it arrived from the
original owner, I was floored at how NEW it looked. Very well cared for. First time, in a long time that
I bought something from someone online and it exceeded the description given by the seller.
And as I said, it works great.
  One question for you Alan, since I do not do OTR trucking but, regional/local off road trucking is
there an antenna (screwdriver or another) that you would recommend I use, other than the whip/
auto tuner combo? I use an Alpine Screwdriver antenna on my pickup and I know that that particular
antenna would never hold up to the abuse of off road trucks.
Thanks for your advice. (oh, and I do read your website, very valuable information there and much appreciated)

Posts: 3746

« Reply #3 on: December 21, 2010, 08:28:54 PM »

hi James,

join other ts-50 and ts-60 fans here,
you may find an answer there should you
keep the ts-50 in the truck.

Page #7 in the service manual details the NB circuit.

73 james

Posts: 10248


« Reply #4 on: December 22, 2010, 07:18:12 AM »

I don't know which bands you're trying to work with the whip, however.... If you are feeding the whip with coax from the Z-11, the only band which will give you a fair efficiency level is 10 meters. While the Z-11 might match the whip on 20 meters, the loss is well over 80% depending on the feed line to the antenna (I don't know what that is). And, although the cab is made of some composite material, it will still have an effect on efficiency.

No matter the antenna, off-road use requires a decent mounting scheme, and even perhaps an additional brace. I don't do off-road work, but I do have a brace which supports the mast of the Scorpion 680. There are photos of the install in the Photo Gallery on my web site.

By the way, the Scorpion is no doubt the best made of all of the screwdrivers, and you pay for the privilege. The Predator, and the Tarheel 200A are close behind.



Posts: 448

« Reply #5 on: December 22, 2010, 06:45:27 PM »

Thank you Alan for the links. I am a member of the Yahoo group and read it regularly.
I posted my question recently and as yet, have not received a reply. I really do like the
TS-50s and even with the noise, I enjoy using it. (sometimes on long loading waits, I'll
kill the truck and really enjoy using it!!)
  As for my antenna, I realize that it is very limited as it is currently. It works reasonably
well 20 - 10 meters and fair on 40 meters.  The Z-11PRO will tune it on 40 meters and I'm
sure (well actually I know) the signal strength is not very much. But, I do make QSO's with
it 40 thru 10 meters. With 17 being my favorite band and one that I have the most contacts
on.  I know that working DX or stateside is no indication of a properly working antenna system.
And I don't use that as an indicator of how well/efficient the antenna system is. That was the
reason I asked about switching to another type of antenna and eliminating the 102" whip and auto
  I will probably give in and install the ICOM 7000 as I do get annoyed with the noise at times.
And after rereading the TS-50s service manual and seeing that it also uses surface mount components
( I've never opened it up) I agree that there is no reason that the ICOM would be any less durable
than the TS-50.
Thanks again for your time and help.
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