More Nucleus Problems.. PA Related :(

ssybert · Post by **ssybert** » Sun Jan 16, 2005 6:56 pm

Hey Guys...

I'm desparatly trying to get a NUC-II on the air as a repeater in the 33cm band. I've run into headache after headache and am about ready to give up on injecting audio into the exciter. What I'm trying to do now is use an external exciter (GTX) and send the RF directly into the PA, then I can trigger the PA with the external key request from the station. Problem is, when I do this and key the PA, the exciter reports PA LOW and shuts the PA down. Anyone know of a way to make this station just transmit whatever I send into the PA? Worst case, I'd like to be able to use this as a big PA.

Anything you guys can offer will be appreciated.

Thanks, Scott.

Post by **xmo** » Sun Jan 16, 2005 7:18 pm

Have you checked with the members at the 902 Yahoo group?

I believe some of them may be running the Nucleus on 902 amateur.

http://groups.yahoo.com/group/AR902Mhz/

ssybert · Post by **ssybert** » Sun Jan 16, 2005 7:38 pm

Thanks for the tip. I'll check it out. I just joined the group and am awaiting membership approval.

kcbooboo · Post by **kcbooboo** » Mon Jan 17, 2005 6:29 am

Let me guess - you want to use PL on the transmitter and the Nuc won't pass it through ! Our local Nuc on 927 is using 192.8 Hz PL for that reason.

On MSF5000s, the power is monitored coming out of the PA, and only so much time is allowed from the instant the exciter turns on until the PA reports output power. Some of these timing values are RSS-changeable, others are not. Also, if the PA doesn't get enough input power, the controller will shut it down with a fault indication. I found this out when I mistuned an internal duplexer/filter, and the section between the exciter and PA input was producing more loss than was acceptable. Key the transmitter and it would immediately unkey. All it took was one more dB of signal to clear this condition.

I'm not familiar with the available settings on a Nuc, but this could be something worth looking into.

Bob M.

ssybert · Post by **ssybert** » Mon Jan 17, 2005 10:59 am

Well, thats one reason. The main reason is I can't find anyone who can help me get analog audio into the exciter without an Advanced controls station; which mine is not. Last resort is to get this thing to operate a a self contained amplifier only. couple the PA to my external transmitter and use it as a big PA only. Any ideas? did you modify your nuc to accpt analog IN or is it an Advanced Controls version?

kcbooboo · Post by **kcbooboo** » Mon Jan 17, 2005 12:29 pm

I believe it has the advanced controller, as it would pass audio just fine through documented line-in terminals. But PL/DPL just did not make it. We're using 311 DPL in the receiver, but we ended up at 192.8 Hz PL because that was barely in the "audible" bandpass of the unit yet still considered a valid PL tone.

Ours is a 250w transmitter, by the way, and it makes a very nice signal !

Bob M.