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 Previous: The Amateur Amateur: My First One Didn't Work Like That |  Next: State Utilities Commissioners' BPL Task Force Session Yields Some Insights |
By Edward J. Wirtz, W7JGM
October 28, 2004
How to keep "amateur active" on 75 meters with a bedroom corner antenna.
 W7JGM: The bottom unit is an MFJ Speech Intelligibility Enhancer (I'm 81 years old and need a little help with those lost audio frequencies above 1500 Hz). On top of that is the antenna tuner, and above that is the Alinco DX-70 HF transceiver. That's a Drake low pass filter to the right of the transceiver. At the top is a speaker for the handheld 2 meter rig, and next to it is the Clear Speech Digital Noise Filter speaker for the HF radio. To the left on the table is the handheld transceiver and an Anderson PowerPole RlGrunner 12-volt power distribution panel. In the corner of the bookcase and the wall is the 300-ohn twin-lead J pole antenna, which is thumb tacked to the side of the bookcase near the ceiling. Not in view is the W2AU balun that I made to keep RF off the outside of the coax. It is attached at the antenna end of the coax and runs down the wall behind the bookcase. |
 The station accessories: These include the deep cycle, heavy duty battery with PowerPole connectors to patch into the RlGrunner, and a 25 A MFJ switching power supply, also with PowerPoles. Many additional sources of 12 V (including my mobile wiring) are so equipped. |
 The bracket: A close-up view of the "corner" antenna bracket. |
 Doublet: The two mobile whips in a doublet configuration attached to the modified mobile bracket. Quick-disconnect connectors are used so the whips can be unplugged quickly and attached to the car mobile antenna mount. The quick disconnects also allow a quick change in the antenna configuration from 180 degree doublet to the 90 degree corner doublet or for Field Day inverted V use. |
 Space-saver: The whips form a 90 degree angle doublet to fit in a bedroom corner of the apartment. |
 Deployed: The 90 degree configuration being suspended by a bookcase and with twine 6 inches below a curtain rod. |
 Pruned for 75: The stingers originally used on the whips were pruned for the 75 meter mobile band. Bedroom settings required shorter lengths. I did not want to cut the original stingers, since the antennas may also be used again in the mobile. I made some "adjustable" stingers from modified copper plumbing fittings to go on the end of the mobile whips, then I attached car AM adjustable antennas to them. This allowed me to pull out as much length as needed for resonance. The calibrated wooden stick shows the length to pull out the adjustable stingers to match the desired traffic net frequencies. This eliminated the need for an antenna tuner and SWR analyzer each time a new net frequency was needed. One setting covered from 3.945-3.985 with less than 1.5:1 SWR and the SWR was 1:1 at 3.965 MHz. |
 In the car: Here's the portable/mobile 2 meter, 50 W transceiver in my car, mounted on the cover of the deep cycle battery box. The transceiver and the battery use PowerPole connectors so I can patch them together for portable station use or plug each or both into the vehicle battery charging circuit, which is mounted below the dash. The ammeter on the battery case allows me to read the deep cycle battery charging current when it is patched into the vehicle battery circuit when the car is being driven. |
 Distribution panel: The power distribution panel is mounted near the vehicle floor. Any and all power wiring is patched through this panel for distribution to various station accessories. |
At 81 years old, widowed and tired of fixing TV dinners and living alone, I decided to sell my home and move into a senior retirement center, in Burlington, Washington. The move meant giving up the HF and VHF antenna farm. I wondered how restrictive apartment living would be on my 63-year hobby.
Since 1941 I have been an active ham, except for the three years during World War II spent with the US Navy Amphibious Forces. After the war I became active in Civil Defense, ARES, the RACES program (having served as Radio Officer for Seattle-King County) and Navy MARS. I also enjoyed traffic handling and qualified for the Brass Pounders' League in 1948. In November 2003, I made the move to Creekside Retirement Center, for seniors, which consisted of 113 apartments.
My first action in the new home was to explain to the neighbors that I hoped to continue enjoying the Amateur Radio hobby and I was willing to solve any problems if they detected any TVI when I transmitted. I explained how "modern" amateur equipment was designed to operate efficiently and seldom caused interference.
I said that my activity with the local ARES and RACES nets, the Department of Emergency Management, Search and Rescue, the hospitals and the various ARRL state traffic nets would greatly benefit the retirement community in times of disaster to obtain emergency help when electricity was lost and phone service was disrupted.
I mentioned the ARRL's free radiogram service for sending welfare messages to distant relatives in time of trouble. Little did I know that the test would come a few weeks later, after we experienced an earthquake only a few miles from Creekside.
My first attempt was on 2 meters using a Larsen magmount and mobile whip on a metal filing cabinet. I tried running 50 W on the Alinco transceiver for the initial test. That completely wiped out the TV picture. 25 W resulted in severe distortion. 10 W still caused a loss of TV color. 5 W caused no TVI problem. At the time I did not know that my antenna was running parallel to the building's TV cable distribution system and just inches away. At that point I felt that a 1 to 5 W handheld rig was my only option.
Later, after installing the 75 meter HF antenna in a corner of the bedroom, I decided to operate HF and VHF in the same corner. After thumb-tacking a 300-ohm twinlead 2 meter J-pole on the wooden bookcase, I again ran a 2 meter test and found that running 50 W in that location caused no TVI at all. The proximity to the TV cable system was the cause of my earlier problem.
Next came the HF experiments using the 100 W Alinco transceiver on my favorite band, 75 meters.
The superintendent in charge of building maintenance was friendly and wanted to help. I said it would be nice if I could get about 59 feet of wire stretched in the attic above my third floor apartment. His storage room was adjacent to my room and he said he could drill a hole behind my corner bookcase (out of sight) into his room and then up through his ceiling. He had a very restricted crawl space but managed to stretch out my wire.
There was no prominent metal ground to connect to, so I tried using the mechanical ground in the electrical outlet box. Even though the antenna tuner and SWR analyzer said everything was fine, I still had HF TVI. The MFJ Artificial Ground sounded like a possible ground solution, but I still could not run more than 10 W without experiencing TVI. My TVI testing was done using a small bedroom TV set just 6 feet from the antennas.
Next try was using the 75 meter mobile whip from the car with the artificial ground unit. The TVI was still present except on low power. Then I read an article written by John Portune, W6NBC, in the May 2004 issue of WorldRadio describing use of two mobile whips to provide a condensed "doublet" antenna for portable field use. So, another 75 meter Hamstick was purchased to make that experiment. Unfortunately, two 75 meter mobile whips end to end created a 14 foot doublet antenna that would not fit in my bedroom. I figured I would try using the whips oriented at 90 degrees instead of 180 degrees so it would fit in the corner above the bookcase.
This worked out very well. The analyzer showed a 1:1 match but the narrow 20 kHz bandwidth (to keep under 1.5:1 SWR ratio) made it necessary to use the antenna tuner to cover the rest of the band. When checking into the evening traffic nets, I received excellent signal reports from all the evening traffic net control stations with this configuration.
To "clean up" the crude installation I purchased a mobile antenna mount bracket to attach the whips. In addition to the insulated whip connection, two more holes were drilled for the other whip configurations. One allowed the second whip to be attached in line with the first to form a conventional 180 degree doublet. The second hole was used to remount the second whip to form a 90 degree angle. This was done so the antenna would fit in the corner of the bedroom.
Another hole was drilled for mounting a SO-239 coax fitting on the bracket and four smaller holes were drilled to secure the SO-239 with 6-32 machine screws. Although I didn't use it that way, the 90 degree angle would also form an inverted V antenna if suspended by the bracket and would be an excellent match for 52 ohm coax.
When transmitting I was getting RF into the MFJ Speech Intelligibility Enhancer unit. John Portune's article had suggested use of a W2DU balun to stop the RF on the outside of the coax. I made one using 30 FB 73-2401 ferrite beads, purchased from The Wireman Inc, slipped over the coax before attaching the PL-259 connector. The beads were at the antenna end and were held in place using heat-shrink tubing. This completely cured the unwanted RF problem.
About this time, the owner of the retirement and the assisted living complex paid me a visit. I invited him to my apartment to show him the installation. He was impressed but wanted to know how long I could operate in an emergency without power. He was shown my backup deep cycle batteries, which were in plastic marine containers to protect the apartment rugs. He was impressed with what he saw.
A few weeks earlier the Skagit River had flooded the Skagit County area. Burlington is located farther down river from where it hit the hardest. Although our Creekside Retirement Community was spared flooding, it was a close call. The owner had become very emergency concerned. He then surprised me by saying he realized the value of my Amateur Radio station and was going to instruct his building maintenance department to run a special "hot line" from the emergency generator that powered the emergency medical equipment in the assisted living area into my bedroom so I would never be without 120 V power.
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After the antennas were finished we had a 3.8 magnitude earthquake just 4 miles from Creekside. It didn't bother the electricity or the phone service. One elderly resident said he was unable to reach his brother in Little Rock, Arkansas by telephone and asked if he could send a radiogram. The radiogram read, "Earthquake four miles from Creekside (xray) I am safe (xray) love". Since it pertained to welfare I gave it a Welfare precedence.
That message left my apartment at 1735 on the 2 meter Evergreen State Traffic System. It was passed it to the Washington Amateur Radio Traffic System net at 1800 and was given to the net Official Observer Station liaison. I was later told by the resident that his brother received the message that same evening at 2330. The Welfare designation indicated that quick delivery was requested.
I would like to suggest to other hams facing difficult living conditions in their senior years to not even consider giving up Amateur Radio. Bedroom operation may not be as good as your former ham shack with the big outside antennas, but it will still keep you active and happy. Give it a try. My RF proximity to the antenna on 75 meters is very safe when I run 100 W.
Ed Wirtz, W7JGM, is a former RACES radio officer for
Seattle-King County and for Skagit County, Washington. He has held many ARES
appointments, including emergency coordinator and assistant EC, and is
presently an official emergency station in the Washington State Emergency Net.
He checks into the evening 75 meter traffic nets regularly and is a member of
the Radio Amateurs of Skagit County radio club. You can reach the author at w7jgm@arrl.net.
| Previous: The Amateur Amateur: My First One Didn't Work Like That | Next: State Utilities Commissioners' BPL Task Force Session Yields Some Insights |
