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Technical HAM Question

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6 months 3 weeks ago #15286 by Richard
Technical HAM Question was created by Richard
I have a technical HAM related question. My D2 has a Yaesu FTM-3100r transceiver paired with a Comet SS-680SB antenna. The antenna is mounted via a lip mount on the left side of the hood, closest the windshield. Initially, I wired the transceiver to an empty slot in the cab fuse box . I immediately noticed subtle static (a crackling sound) from the car stereo when I keyed the microphone when using either Bluetooth or a USB device music streaming on the low power setting of the transceiver. This was not the case with FM (car stereo). The static got more pronounced on the medium and high settings. Again, this was not the case with those two power setting on FM (car stereo).

I moved the transceiver power and ground directly to the battery, thinking it may be a ground issue, and experienced no change. I wired the transceiver to a separate 12-volt battery, again, no change. I then used my FT-60 and the closer its antenna came to the car stereo, the more static there was when I keyed the handheld. My conclusion was that the antenna’s proximity to the car stereo may the issue, since this was not happening on FM and the car stereo antenna is in the right rear window (so I am told). Removing the Comet antenna wiring would be too time consuming, and I did not have an extra antenna wire to test my theory.

I decided to drive over to Ham Radio Outlet in Anaheim to look at roof rack antenna mount options and discuss the issue with them. Their conclusion based on what I have described was that the D2 130A alternator was the problem, and they recommended I move up to a 200A alternator. The idea, as communicated to me, was that the transceiver was drawing excessive amps form the system, hence, the noise within the car stereo when transmitting. Since I tested the system with external power sources (battery and handheld) not associated with the alternator, I found their conclusion a bit hard to accept.

So, any thoughts? And thanks in advance.

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6 months 3 weeks ago #15287 by JimBiram
Replied by JimBiram on topic Technical HAM Question
I call BS on the alternator theory. Most likely it is one of the following:
1. The location of the Yaesu to the D2 radio is too close, or the location of the antenna to the D2 radio/windshield is to close.
2. The Comet Antenna has gone bad and is putting out spurious RF.
3. Your Yaesu needs a choke on the wiring to reduce rf from the wiring itself.
4. The power to your D2 radio needs a choke to reduce rf coming through the power.

I would have the Comet antenna tested, or get another antenna. I'm partial to the Diamond 770 antenna and the Diamond trunk mount, which adapts very well to my tailgate on my LR3. The Diamond has been bulletproof for several years now. Antennas do go bad, as I had an MFJ that went bad in 6 months.

Hope this helps!

Every Day is a good day surfing...some are just better than others
2005 Java Black LR3
K6JKB

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6 months 3 weeks ago - 6 months 3 weeks ago #15288 by NineZero
Replied by NineZero on topic Technical HAM Question
I agree with Jim,

You should choke the power to both units as close to the devices as you can. It doesn't sound like you're anywhere near Santa Clarita, but if you find yourself up here I would be happy to test your antenna, if you're only working 2M you shouldn't be in a low enough band to interfere with 12v electrical, so that antenna might be bad or in need of a tuning stage.

I'm also a Diamond fan, I've had a few different model antennas from them over the years and all have been great, I've snapped off a couple of them so I've recently gone to a cylinder type antenna on the Defender, it limits the range but it won't snap off on tree limbs, I switch back to the full size antenna when I'm off the trail or if I need to get more distance.

Jim I just had my MFJ HI-Q Loop die after less than a year... not sure that they have the most rigorous quality control over there, they did replace the complete unit for free though.

Steve Beres
K6YYC

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6 months 3 weeks ago #15289 by Richard
Replied by Richard on topic Technical HAM Question
Steve / Jim,
Thank you so much for the quick responses. i had an extra antenna, tested with it, and the problems persists. I will work on choking the two power lines and relocate the antenna toward the rear of the vehicle.

If all else fails, I may need to take a day trip to Santa Clarita...thanks for the offer Steve. Much appreciated.

Richard

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6 months 2 weeks ago #15290 by Richard
Replied by Richard on topic Technical HAM Question
The the solution was number 1...relocated the antenna to the back of the truck on the roof rack, and the problem went away. Jim called it.

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6 months 2 weeks ago #15291 by JimBiram
Replied by JimBiram on topic Technical HAM Question
Ding Ding Ding!!! Give the man a cigar!

Glad that it was an easy fix!

Every Day is a good day surfing...some are just better than others
2005 Java Black LR3
K6JKB

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