Icom X-Band 50 Noise Problem

[LMRAlaska]

Has anyone experienced a noise problem with the Icom X-Band 50 repeater? I have a new one from the factory which has been returned to them once already for this problem and sent back as fixed, but the noise is still there. When generating a CW carrier into the UHF-FM side, the VHF-AM ground to air side transmits about 4% modulation of pure noise on battery power which is unacceptable to me but when on AC, with its internal switching power supply there is a whine in the background which slowly drifts up and down in frequency which produces about 8% AM modulation out of the ground to air side.

When running on DC power the level of the whine goes down to near the same level as the noise, but is still there telling me this is an oscillator problem within the unit, if it were the switching power supply it should go away completely when it is powered down and only running on 12 VDC. This problem is present when both the UHF and VHF radios are on 50 ohm terminations/dummy loads.

Anyone else observing this problem?

 

[12dbsinad]

The first thing I would do is check both radios on a simpex frequency individually. Listen out of the radio speaker while transmitting, then do the same with the AM radio. If both are clean, chances are the noise is being generated with the interconnection. Next, try powering the radios directly bypassing the internal AC/DC switching. Use extra caution as not to short the leads together. I'd suggest putting a fuse lead on both power and ground on each radio just to be on the safe side. As far as the noise (not the whine) what type of noise is it? What does it sound like?

 

[LMRAlaska]

Thanks, the customer has decided to cancel the use of this system, send it back to Icom and use another radio. No further troubleshooting to be done now, unfortunate for Icom, if this had worked out they were going to buy several of them for other locations throughout the USA.