N2 carrier

[743SEPA]

Lately while transmitting on side band my N2 will throw a carrier of about 6-8 watts whenever I'm not talking. It's bad enough on my nets that people say it sounds funny or is not as strong a signal as usual. Any ideas?

 

[Big Kahuna]

Can you get it to go away by adjusting down your mic gain? Just wondering if it's picking up background noise or the gain is set too high.

 

[743SEPA]

Still does it with mic gain all the way down,different mics too.

 

[Big Kahuna]

Hmm may be a bias issue which I think other members have run into with the 2970N2. https://www.worldwidedx.com/threads/rci2970n2-bias-help.107050/

 

[Handy Andy]

You may want to look at this thread too...

https://www.worldwidedx.com/threads/rci-2970n2-carrier-on-ssb-only-into-antenna.242239/

In Both Big Kahunas' and the link above - both threads are looking at the MOSFET finals as having their bias set too high for safety.

The Bias can cause this carrier to appear and seem to garble up speech, so if the carrier is from an IF issue that's one thing - Carrier Balance may need to be looked at, may be needing to being reentered on the drifted off Xtal base frequency.

IF the carrier is from the frequency you're on - then the MOSFET's may be biased to a point where their failure is imminent as in catastrophic failure and possible blown power supply and or it's traces. This kind of oscillation of carrier is caused by the "ringing" effect - a mixer product that both the SSB IF Xtal that trims off Carrier and opposite audio band and from the AN612 (Balanced Modulator) is not trimming off the mixer skirt of carrier exactly so it and the other mixer IF - when combined - gets made into the carrier and thrown in with the Signal as a re-injected AM signal that is not modulated, just carrier - from the MIXER in the TX side - but it's not it's fault, it's the Balanced Modulator or a bad tune-up or drifting off IF Xtal that the Balanced Modulator now needs to have its' CARRIER BALANCE control re-tweaked to offset the drifting Xtal(s) (Yes, can be more than one)

 

[Big Kahuna]

After reading all this I seem to remember a brand new N2 I had tested had the carrier issue (as well as it was putting out way too much power) and it went back under warranty for service and afterwards worked great.

That's one radio I wouldn't really recommend messing around with since there's a lot going on, unless you are highly qualified - I'd send it in to a (good) Ranger service center.

 

[Shockwave]

While connected to the antenna, calibrate an SWR meter for the 6 watt carrier you see on SSB and check the SWR. If it is much higher than normal, the problem is the PA board is oscillating. Have a look at 8 transistors making 200 watts PEP:
http://cdn1.bigcommerce.com/n-yp39j..._182J_P02__52958.1457057805.1280.1280.JPG?c=2