fm35 problem

[malpighi44]

I recently purchased the FM35 and TM100 antenna. The problem I am having is that, on broadcast, I am hearing what sounds like leaking between the stereo channels. This is most noticeable if one of the audio inputs on the FM35 (left or right) is disconnected. A low volume, scratchy, distorted version of the broadcast audio is heard through the corresponding disconnected channel on FM reception. A variation of this effect is heard when broadcasting in mono.

I have tried many different audio sources including a Kenwood component CD player (line level source). I have also used different cables, audio level settings (inc power and volume on the FM35) and antenna setups. I even re-read the FM35 and TM100 manuals.

The TM100 is attached to ~40 feet of RG213. I tried different transmitter and antenna locations. I have even tried a different antenna cable (~30 FEET RG58). I have also tried a dipole, a long wire and whip antenna at low power settings. none of these modifications has had any effect on the broadcast quality.

I have contacted Ramsey Tech and shipped them the device for testing. They have checked the device, shipped it back to me stating "no problems found". They did suggest that a high SWR could cause similar problems and suggested I check my antenna and feed line.

This is most annoying and I am running out of ideas. I am thinking about buying an antenna tuner and SWR meter but am searching here before I do.

For what it is worth, before I bought the Ramsey, I was quite happy with a small "Sound Sender" device I bought from radio shack years ago. With the voltage cranked up and a long wire clipped to the whip it worked very well in the house, driveway and yard, but had only limited range at the far end of our property. The Ramsey device is more powerful and sophisticated to be sure, but is it really that sensitive to set up?

I searched the forums but did not find any exact match to my problem. Any advice or stories of similar experience are welcome.

Hoping for some help.

Thanks for your time,
malpighi44

[krankshaft]

How long is your antenna line if its too long and you just coil it up by the transmitter or the antenna it could cause problems. You should cut the line so that there is no coiled slack between the antenna and transmitter.

Is the balance adjustment centered?

[malpighi44]

Thank you for your interest krankshaft.

The two antenna lines I've tried with the TM100 have been ~40 feet of RG213 and ~30 FEET RG58. both lines were straight, non coiled and effectively straight up. Other antennas and lines were random configurations here and there. As I stated above I've even used a whip (on low power).
Yes the balance is centered. In fact I've experimented with balance levels on both the transmitter and audio input devices when possible. With balance 100% left or 100% right or centered the audio leaking persists.

Of note here, and perhaps not stated clearly in my first post, is the fact that no matter what antenna or settings I used the problem is no better or worse. It just persists at a consistent level no matter what I've tried.

I am beginning to think it is an internal RF leak. I'll have to contact Ramsey again and see how they tested it. It really is most noticeable with ear buds and the effect is more pronounced with certain specific audio (voice and music).

Cheers
malpighi44

[radio8z]

It could be that the high frequency content of you audio is interfereing with the 19 kHz. stereo pilot signal.

The FM-35 may have built in audio lowpass filters to prevent this (I don't know this for sure) but you could try low pass filtering your audio through software (cut off above 15 kHz.) and check if this fixes the problem. If so, then you know where it is coming from. It did here, but I am using a FM-25A with no built in filtering.

Neil

[avexglobe]

Did you ever get the problem fixed? I'm curious to see what it was because I use the same setup, except that I have the Stereo Transmitter Companion also attached to filter the signal more.