[W2CRA] 375 System: Recent Problems, Fixes and Status.

[William Powell]

375 repeater system: Recent Problems, Fixes and Status.
 
Summary:
We have 6 voted receive sites: Cherryville (control site), Bloomsbury, Mt. Kipp, 
Murray Hill, Kingwood and Linvale and one transmit site at Cherryville (County 
tower ~1/4 mile from control site)
The system showed some level of degradation for about a week preceding the first 
outage when the last on-line Rx site went down.

Recent Actions:
I made a tower tour Sunday last and Ed (N3MSK) and I repeated Monday afternoon 
with test equipment.

Mt. Kipp
OOS due to 440 link yagi being removed from tower to make way for NJSP 
antennas.  Miscommunication issues at the root of the problem.
Immediate solution was to place 440 link on diplexer (in place of discontinued 
015 severe Wx net link) with 375 receive antenna for now.
Long term is to mount a single 440 yagi for the link and reroute the existing 
feedline.
 
Kingwood
My initial "tower tour" trip on Sunday found the link package apparently working 
but the feed lines hanging only 5 feet off the ground.  I assumed a link 
receiver issue at the control site.  Monday afternoon it was apparently working.
???
Long term we need to run a "messenger" line (plastic coated dog run wire) from 
tower to the phone pole to support the 2m and 440 transmission lines as they are 
hanging way too low at the outhouse end and also laying on top of the newly 
installed ice bridge inside the fence.
Also to be addressed: the tower is scheduled to have a 20' section added at the 
top.  What about our receive antenna? We need to make sure we are "covered" and 
not lost in the shuffle.
This would be a good site to trial a commercial link package which would allow 
us to locate into the NJSP shelter with the County radio equipment.  We would be 
able to share the county high band receive antenna (no transmitter there) and 
benefit from generator backup and loose a power bill.  Down side: Begging 
permission and the cost ~$1300? for the link package; No "ham" equipment 
permitted - only "professional" commercial grade gear allowed.
 
Linvale
On my initial trip I couldn't get it working.  Had power but no joy.
When Ed and I returned (with test equip) we found a "deaf" 2M receiver front end 
which had evidently grown a "whisker" (known problem) which cleared when Ed 
re-tuned it.  The 440 link transmitter also exhibited low transmit power that 
came back up after an "iffy" transistor solder joint re-soldered.
 
At the control site:
The Bloomsbury link receiver had a bad audio/squelch board which Ed replaced.  
Now up
The 2m receiver at the control site had a bad COR transistor which Tony 
replaced.  Ed also discovered an apparent desense issue with that receiver - 
only 1/4 mile from the transmitter - the noise you sometimes hear.  This is 
caused by the nearby transmitter clobbering the receiver front-end (which has a 
preamp and GREAT sensitivity).  We dug up a cavity and put it inline with the 
receiver but the problem still happens intermittently.  We're working the issue; 
a notch cavity at the transmitter and / or converting the receiver to true "and" 
squelch.
Tony yet again re-worked the controller, making some programming changes and one 
hardware change.
 
Current status:
Controller now allows ID "talk through" and has lower volume and courtesy beep.
All sites currently up (for a given value of up) except Murray Hill which needs 
looked at.
Voting working with only one site having "different" audio.
Control site 2m Rx has squelch / desense issues to be addressed.
 
Near-term work that needs to be done:
 - Link antenna work at Bloomsbury and Mt. Kipp:  Ed and Wes? with ground 
support.
Take 440 dual yagi and side arm from Mt. Kipp to Bloomsbury and mount at ~80' to 
improve that link (need ~150' 1/2 hard line)
Move current Bloomsbury 440 link yagi to Mt. Kipp for that link using new 
mounting position and rerouting existing cable.
 - Transmission line work at Kingwood: Work party and Michael to go up the 
pole.  Need PROPER eye bolt and plastic covered dogie run steel cable and cable 
supports - NOT cable ties!
 
 - Control site cleanup and power.  I have a line on a 6' outdoor cabinet to use 
in repackaging the control site into one box.  Can "scrounge" power parts.
 
Long-term issues to be addressed:
No real (easy) way to know when a receive site goes OOS.  How to know?
Need for regular maintenance (testing) and people to do.
Need to bring at least 2 more people up to speed to help maintain the system.  
Will be expected at work parties
Consider commercial link packages.
 
Bill Powell - WB1GOT