73 membership dues are current and an appropriate reserve balance is in our accounts
NCOCRA Annual Christmas Dinner:
The OCRA Annual Christmas dinner will be held this year at the Hillsborough Exchange Club on Monday, December 11, at 6:00 PM. We are striving to have attendance be above 60, which will secure the cost at $20 per person. Reservations for attendance are required no later than December 4th. Please email Lad (W4ORD) via the Yahoo reflector reserve your reservations.
Danny Hampton made the Club aware that our current Kenwood TKR repeater series is being discontinued. As such, Dave (W4SAR), club president, made an executive decision to purchase an extra repeater as a spare.
The new backup repeater is identical to the one currently in operation. This particular model is now discontinued, thus the urgency to purchase. The new repeater was $1,000 and can be cloned to provide additional continuity for the existing repeater for many years.
For comparison, a newer repeater model is roughly $4000. While the new repeaters are both digital and analogue, the additional cost would not have provided an identical clone to the existing repeater. With the cost of tower work now around $1,000 per incident, cloning the existing repeater and having a ready backup made better fiscal sense than purchasing a newer repeater model.
Elmering or mentoring has long been the backbone of Amateur Radio. While technology constantly evolves, the human interaction between hams will not be replaced and will always remain one of the hobby’s strongest traditions. As such, there is a need to begin Elmering the next generation of FM repeater managers. Understanding repeaters is a valuable skill for any ham, and especially for those ham’s interested in emergency response.
Please let Dan (KR4UB) or Steve (W3HAL) know of your interest to learn about repeater management.
Public Service: AUX Comm site is down. Work is in progress to restore.
ARES Portable Station Equipment, Steve (W3AHL)
Many ARES/AUXCOMM events are best supported using a portable radio station.
“Portable” is defined here as:
Capable of being set up inside a building, such as a shelter.
- Twenty+ watts of output power.
- Antenna, mast and coax that allows placing the antenna outside, if necessary.
- Battery back-up capacity for 12 hours of heavy usage.
Often your mobile radio and antenna can serve as your portable go-kit (if easily removed from the car) by adding a battery, coax and mast. An HT is not recommended as a primary portable station, although with an exterior gain antenna and a 12 VDC 7 AH battery, it may be sufficient for many locations.
Almost any VHF or UHF transceiver is suitable for portable operation. A dual-band radio is desirable, but lacking that you may be able to use an HT or another single band radio to monitor activity on other nets. The radio should be programmed with all of the frequencies in the ARES Communication Plan. It should be used weekly or monthly to verify it is working.
Many ARES operators build a radio go-kit containing the radio, power supply, speaker, microphone, headphones, power/SWR meter and battery voltage meter permanently mounted in a self-contained box that may be weatherproof when closed. Others keep their gear in a duffel bag, tote container, or just remove their mobile equipment when needed for portable operation.
Don’t forget to include “office supplies” like pens, note pads, ICS-213 General Message forms, stapler, tape, a small All-In-One printer/copier/scanner, etc.
Choosing the correct portable antenna system may be the most important decision in assembling your go-kit. If local repeaters are off the air due to a storm and more distant repeaters or simplex operation is needed, your normal antenna may not be adequate.
We try to deploy in teams of 2 if enough volunteers are available. That allows pooling of resources if one operator is missing some items needed for the site.
Some factors to consider are:
1. Many commercial buildings will attenuate your signal and require using either an external antenna or one mounted near a window facing the required direction.
2. A dual-band base, mobile or j-pole antenna that can be mounted on 15 feet of mast, with 75+ feet of coax is recommended. A chart at the end compares the relative signal strength of typical antennas at various heights. A 5’ base antenna mounted 15’ high will have 12 dB more gain than a mag-mount antenna on your car. This is the equivalent of increasing your transmit power from 20 watts to almost 300 watts, without using more battery power.
3. The mast can be a commercial push-up pole, 1.25” TV mast in 5’ sections or military surplus mast. Fifteen feet is a good height that can be supported without guy wires and improves the antenna gain by 3-5 dB compared to 5’ height, or much more if it clears nearby obstructions.
4. You should try to have several options for supporting the mast. A tire board is good if open parking is near your operating position, which is often not the case. A 3’ roof tripod can be used with a tire board, 12” long spikes driven into the ground, or with large rocks or cement blocks. If guy wires are used to support the mast, they must be well-marked to avoid injury to pedestrians and cars. This is often impractical, especially at night. Chemical or LED battery powered light sticks on guy lines are a must. Make sure they last all night.
5. Coax and power cables must be routed to eliminate any hazards to foot traffic. Red duct tape can secure it across aisles, but may leave a residue that is hard to remove. White gaffers tape is a better option. RG-8X coax can often be routed under a door threshold or window seal, but has 8 dB loss at 440 MHz per 100’. Several shorter pieces of coax will allow you to use only what you need and reduce loss. Larger low-loss coax such as 9913F or Davis Bury-FLEX work well for long runs and only have 2.5 dB loss. Use a short piece of RG-8X to go under a tight door if needed. Waterproof your connections.
6. A simple power/SWR meter should be used to check your antenna & feed line before operating. It’s better to find a shorted or open coax with a meter than by smelling smoke from your radio.
7. Headphones are a must! You will be able to hear messages more clearly and those sharing the space will appreciate the silence.
8. Always carry a charged battery that will allow at least 12 hours of operation, assuming you will be transmitting 20% of that time typically. An 80 amp-hour battery is rated to provide 4 amps for 20 hours, but your radio may not operate below 11.2 volts, so you may only get 12-15 hours instead of 20. And batteries that are old, too cold or have been over-discharged may provide only a fraction of their rated power. Carry a spare and learn how to load test a battery.
9. The battery cables must be fused near the battery. If the battery is connected to a power supply, use dual diodes to isolate them (or a West Mountain PowerGate), or you may fry the power supply when you lose AC power. Battery terminals should be insulated to prevent accidental shorting. Looded-cell batteries should always be in a battery case to prevent acid leakage during charging.
10. Use Anderson PowerPole connectors on all power cables. Borrow a PowerPole crimper to make your cables. Don’t use a single-dimple crimper if you want reliable connections.
11. If your antenna is inside the building you may desensitize other agency’s radios or interfere with public address systems.
12. Frequently check your antenna, mast, coax and power for safety issues. Don’t allow your station to become part of the emergency!
13. Once you get your portable go-kit packed up, actually use it occasionally, even if it is just in your back yard during the Saturday ARES Training Net.
Portable Antenna Performance Comparison
Relative gain in dB compared to a mobile mag mount, as measured from W3AHL to W4UNC 443.475 repeater at UNC Hospital (5.5 miles) in 2009 using a spectrum analyzer.
Gain dB Relative to Mag Mount
|Diamond X50NA (dual band base)||5′ Tripod||
|Diamond X50NA||10′ Tripod||
|Diamond X50NA||15′ Tripod||
|Diamond X50NA||25′ Roof mast||
|Diamond NR770HB (dual band mobile)||Mag Mount on 5′ Tripod or SUV Roof||
|J-pole dual band (300 ohm twin-lead DIY)||top 10′ above ground (hung from gutter)||
|18″ whip for HT||5′ Tripod||
|18″ whip for HT||hand held (varies greatly with slight movement)||
+2 to -16
|6″ Rubber ducky for HT||5′ Tripod||
|6″ Rubber ducky for HT||hand held (varies greatly with slight movement)||
-3 to -23
Note: Most Mag Mounts have a 3 dB loss (50% of power) compared to body-mounted antennas with shield connected to metal body panel.
OCRA and the DFMA are trying to raise money for the January 2018 Bouvet Island Dxpedition. Both clubs will each match donations up to a total of $200. While cash and Paypal are acceptable forms of payment, checks are preferred. Please make the check out to Bouvet Dxpedition and add OCRA or DFMA in the check comment section. Additional donations can be made on the Bouvet Dxpedition website.
The joint field day operation for OCRA and DFMA has ranked 3rd again nationally. Second place went to W4IY, who had 1200 points on us. Please visit the ARRL Field Day results for more information.
Great Job Team!
We will begin focusing our 2018 Field Day efforts in January. Have a Great Holiday Season.