ASII UHF "growling" on transmit

[Will]

UHF Hi ASIII, transmitter "growling" on transmit like RF
feedback. I had thought it was due to using the older spkr/mic and the RF is getting into the s/m cable near the antenna. I found it even does it on the test bench into a percision dummy load/wattmeter. The ASIII does not "growl" on the LOW power setting, it is set to
2.3 watts on LOW. 4.0 on Hi..

"Also if you replace the chassis I would recommend getting an extra RF Ground Clip." would this have something to do with the problem?

[RocketNJ]

sounds like a shield is missing or does not ahve a good solid ground.

George

[ASTROMODAT]

We used to have a similar problem with our ASTRO UHF Saber IIIs. We solved it by switching to the stock whip (e.g., speedometer cable) antenna, as opposed to the short, stubby helical antenna. In the end, we entirely changed over to the XTS3000 series. In your case, since you are experiencing this problem even on a dummy load, it would seem you have a real problem. Maybe it's time to spend the $375 flat rate and let the Repair Center deal with it. These kinds of broadband noise problems oftentimes involve stray ground loops and the like, and they can be intermittant and therefore extremely difficult to track down. Let The Pros struggle with it (and you will have a repair warranty to rely on for a while, which will be especially nice if it's a stray issue, and comes back again)!

Larry

[Will]

I think it may be a shield problem because it does not always do it. I did check the internal shields as best as I could not having worked on these. I did add the thermo pad on the PA heatsink to the frame and thought it was better, but one shield looked like plated plastic makes me wonder.

[KG6EAQ]

Don't forget Will... my first one was missing the RF shield and it commited suicide on me.