Well Mostly correct there, I've got the power back up, still not full bore, but did find out why the power was coming up slowly, it was the exciter, one of the coils was loose, fixed it and power back up, but still missing some. 200 in for 120 out, so not quite there yet. Might see about the cables, I think they were originally cut for 147 Mhz, might need to be changed to get a better match. I'm gonna call TX-RX tomorrow and inquire about them.
Thanks. Mathew -----Original Message----- From: Mr John Lloyd [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 05, 2005 10:26 PM To: [email protected] Cc: w9mwq Subject: [Repeater-Builder] Duplexer Issue again! I'm confussed or Lost Message: 24 Date: Tue, 05 Apr 2005 21:12:14 -0000 From: "w9mwq" <[EMAIL PROTECTED]> Subject: Duplexer Issue again! I'm confussed or Lost > Ok, I'm sure these duplexers are tuned correctly, but > here is what is happening. If I inject 1.5 watts > into the transmit side of this duplexer I get about > 95% of that back, with about 1.4 watts from the > duplexer. Then I pump 130 watts into the duplexer > and only get 60 watts back. Why such the loss with > the higher power? One possibility is that your transmitter is not matched to the Duplexer with the jumper cable you used to hook them up with. Perhaps your 120 watt transmitter is folding back and reducing power with the mismatch. Another thought is that your 120 transmitter may be spurious and the filtering of the duplexer is reducing these spurious emmissions. Did you check your transmitter with a spectrum Analyzer to verify it is not spurious? > Transmitter and amp are both ok on a dummy load, > looks good on the spectrum analyzer, no problem > there. The amp is rated 2 watts in for 200 watts > out. I put in 1.5 watts, to get the 130 watts out, > that is fine. Other part that I am confused with, > the amp into a dummy load, starts out at 100 watts > and then gradually creeps upto 130 watts over about > 30 seconds. Current draw on the power supply is 18 > amps, from a 70 amp astron. Could it be that the > power supply is slowing giving juice to the amp, > kinda like the caps might be weak? Any thoughts? Mathew It sounds like either the power control circuit in your 120 watt pa is drifting when transmitting or your power supply is drifting higher in voltage when it warms up. You could have an unstable power control circuit in your PA. You did not say what model of transmitter you were using. The other possibility is that your Astron power supply could be increasing in voltage over time when it warms up from use. To check this, use a digital voltmeter and watch the 13.8 volts at the 120 watt Amplifier end and record the voltage when you first transmit and then watch it to see if it creeps upward when it is putting out 120 watts 30 seconds later. Another possibility is that the wires between the power supply and PA are too small of gauge and are heating up when you transmit. Usually the power output drops in this case. You should be using 8 guage wires or larger depending on how long they are. John, K7JL __________________________________ Do you Yahoo!? Yahoo! Personals - Better first dates. More second dates. http://personals.yahoo.com Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
