|The Las Cumbres Amateur Radio Club Newsletter
Summit Sentinel, June 2003
Contents of the Summit Sentinel, mailed to members June 2003; Editors: Dan K6PRK and Jey KQ6DK.
Volume 25, Issue a
"From the Sierra to the Sea,
…This is K6FB repeater"
|Las Cumbres Amateur Radio Club
P.O. Box 2415
Cupertino, CA 95015
- Dan K6PRK
The old dilemma of co-channel users on our 2-meter and 220 repeater pairs has been solved. We now have a clear channel on both machines.
Looking back over a year, we had some concerns about the high SWR on the 2-meter antenna in the 100-foot tree. As a result, we bought a Diamond 2-meter base station antenna and asked John, KJ6ZL to climb the tree. He swapped out old Phelps-Dodge Stationmaster antenna for the new Diamond.
The Diamond antenna seemed to work as well as the old Phelps-Dodge Stationmaster, but there was some doubt about the maximum coverage area and the down tilt on the new antenna.
We had a few windstorms after the Diamond 2-meter antenna was installed. The Diamond is very limber and waived in the wind easily. In June of last year we began having some serious intermittent desensing problems with the 2-meter repeater. Every time I went up to the shack the problem would disappear, only to return shortly after leaving the site. (That figures!)
The desense symptoms were lack of sensitivity with hissing and popping. The repeater would pump or key up and drop rapidly when you held a steady carrier into it.
The pumping is due to a sensitive receiver when the transmitter is off, but when the transmitter comes on, the desense starts and the repeater unkeys and the cycle starts over.
The only fix was to lower the power level of the repeater to about 5 watts and the problem would diminish. Other times the repeater would be perfect with great sensitivity. Yet, running low power is bad since it gives the impression that the channel isn't being used to those wanting to use our repeater's frequency pair.
I removed the duplexers and brought to my house for complete realignment, and then returned them to the site. The duplexers are in excellent condition and meet specs. This did not improve the desense problem.
Finally the problem became so bad that it was desensed it all the time. If a dummy load were substituted for the tree antenna, the problem would go away. It was determined that the Diamond antenna in the tree either has some water in it, or it has a loose element inside it and is arcing. The arcing causes spurs on our input frequency and desenses the repeater receiver.
The Diamond antenna must be taken down and either replaced or repaired.
The repeater is currently using 2 antennas. We are receiving on the tree antenna and transmitting on the packet antenna, which is about 75 feet lower than the receiving antenna. This makes a difference in coverage for the transmit portion of 2-meters, especially close in to the repeater site.
A work party was formed to repair the old Phelps-Dodge antenna at my house. It was taken apart and all the joints in it were re-soldered. The antenna was then checked for proper performance.
The next step is to reinstall the Phelps-Dodge antenna back on the tree. This should clear up our desense problem. We hope to return the P-D antenna to the treetop sometime in June.
Another repair item that has cropped up in the past several months is our remote base. We have a remote base that can be operated on 10-meters, 220, 440 or 1200 MHz. We were using the 220 remote base module to link the 2-meter/440 into the 220 machine. Something happened either to the 220 module, or the remote base interface itself. Currently there is only a 1-way link between 2-meter/440 and the 220 machine. The 220 repeater will come up when you talk on 2 meters, but won't work the other way around. This problem will be investigated soon.
Once the problems get ironed out with the remote bases, a complete instruction sheet will be provided to the membership of how to use the remote bases.
We now have a new amplifier on the hill for 2 meters. It has a capability of supplying almost 100 watts at the output of the duplexers. The amplifier is adjusted to provide 65 watts maximum at the output at the duplexers to be within the terms of our coordination.
As you can see a lot of work has been done at the repeater site, but a lot of work is still waiting to be done.
Thanks to all that helped me!
Dan Smith K6PRK
- Jey KQ6DK
In April you should have received a personalized letter, detailing your roster information along with a request to renew your membership.
For those who have already renewed, I thank you for your support. Your support keeps K6FB on the air for all of us!
Yet, as of mid-May less than half of our members have renewed. Perhaps this is a sign of tough times, or that interest in the club or hobby has wandered in recent years.
If you have chosen not to renew this will be your final Summit Sentinel. We're sure going to miss you! Really!
You can review your renewal status by looking at the mailing label for this newsletter. If it indicates '03' then you're current. If it's not '03' then perhaps we'll hear from you soon! Renewal dues are $25; look for the address in the masthead at the top of the Summit Sentinel.
- Lou WA6QYS
Las Cumbres ARC members are invited to join SCCARA for Field Day at Mt Madonna Park. Mt Madonna is on Hecker Pass Hwy between Gilroy and Watsonville. A planning meeting will be held on Monday, Jun 9, Kaiser Bldg K on Kaiser Drive, Santa Clara at 7:30. If you wish to participate then please complete an application today! See next page for more information.
2003-04 Las Cumbres ARC DirectorsPresidentKen Carey, KN6CK
Voice Repeaters (All are linked)
- K6FB/R: 145.450 MHz (-) PL=100
- K6FB/R: 442.575 MHz(+) PL=100
- K6FB/R: 223.880 MHz(-) PL=100
- K6FB-1: Digipeater: 145.050 MHz
- K6FB-2: Bulletin Board: 145.05 MHz
- K6FB-7 Node (alias LCARC): 145.050 MHz
- K6FB-5 tcp/ip "losgatos" [18.104.22.168], 145.750 MHz
© 2003, Las Cumbres Amateur Radio Club