August 20, 2005

Traverse Link RX checked


After hearing what sounded like noise on the 440.05 link from the W8TVC location I found no real 'smoking gun'. All connections seemed to be stable and the measured sensitivity appeared to be normal. However, since the new 440 duplexer was installed there seemed to be intermittant periods of 'not quite solid DFQ' signal from the link transmitter. I swapped the antennas for the link receiver, putting it on the former 440 repeater antenna (it had been diplexed on the dualband X50 remote base antenna). More research to follow in time.

I also did some fine tweaking on the new UHF duplexer--- all was good.

73 John

August 13, 2005

New 440 duplexer


Tonight I installed the 'new to me' (er, used --- via ebay) Cellwave PD524 six cavity UHF duplexer at the repeater. I was successful in removing the four cavity DB products duplexer that was on loan from Evan N8JKV. The system now has three cavities in the transmit side and four cavities (one additional Motorola bandpass cavity added) on the receive side.

While there was no improvement in receive sensitivity (which already is quite good), the power fed to the feedline went from 35w up to 57w, quite an improvement.

This frees up the former PD524 duplexer for other uses.

73 John

August 05, 2005

6mtr RX noise problem


There's a severe noise problem affecting the 52.42 receiver at the Empire/GlenArbor repeater site. The noise is intermittent, but when it's there it's strong enough to render a 100w signal within visual view of the repeater antenna rather noisy, sometimes unreadable.

On Sunday 7/31 I spent a few hours trying to locate the source of the noise and had no success. Both the Mitrek transmitter and receiver were swapped out for the RCA backup units with no change. The antenna system was switched over to the (still in place) older system with no change. Each section of the duplexer was individually taken out of the system and there was no change... the TX/RX antennas were even split and no difference was noted. The amount of desense did not depend on the amount of power the repeater transmitted-- as it was the same at 5w as it was at 50w. All RF jumpers were swapped out to no avail. I ran out of time and returned the equipment to the way it had been previously-- except for the removal of the ARR 6m GasFET preamp from the 52.42 receiver.

During the past week the noise was prevalent quite often. The weather was unseasonably hot and muggy. When the noise is present, the repeater is useable if the station accessing it is within receive range of the W8TVC site receiver-- as the voting system does it's job well to allow that receiver to 'pick up the slack'.

Today the weather was more seasonable and with temps in the 70's (as opposed to the 90's) the noise is not present. Tonight I ventured up to the site to look into the problem and was able to document what the receiver saw from the antenna when there was no noise present. The system appeared to be functioning properly.

73 KF8KK