Wednesday night (1/6), I decided to work on improving my 220 MHz mobile "station". Up until now, I've been using a Comet tri-band whip with a 5W TYT F9 HT, and that's worked okay. But I've had a 5/8-wave mobile antenna sitting around for about a week now, waiting to be tuned.
The Opek VH-1216 is a monoband whip with a matching network at the base. It's pretty simple; no phasing coils or loading coils. Unfortunately, it doesn't ship tuned to the amateur FM portion of the band. I really don't have the tools to nibble away at a stainless rod, but I have a brother in St. Louis Park that does. He has an angle grinder that slices through the rod easily, and a wire wheel to take off the burr. It took me longer to explain the process to him than it did to make the first cut and test it with an SWR metre. In total, I'd guess that two inches at least had to be trimmed off, but the match was nearly perfect on FM simplex frequencies and pretty darn good at repeater input frequencies.
My expectation was for a bit of improvement over the Anli DC-124H tri-band whip and the Comet SSB224 tri-band whip that I'd been using before. Multi-band antennae are always a compromise, and are intermod magnets because they are open to a much larger range of frequencies than a monoband. Mostly, though, I just expected a better match by using the monoband.
I was using my Kenwood TH-F6A HT for a mobile rig. Normally, this isn't a great choice because the F6A is a wide-band receiver that works from HF to 1.2 GHz, and it has a front end that will let virtually anything through for that reason. I did this because I wanted to see if a monoband antenna would reduce the intermod issues.
To test the antenna, I chose a long-shot repeater that I had trouble reaching from home: the 223.900- (100.0 PL) Aggrandizer. Being in one of the lowest spots in St. Louis Park, and running only five watts, I fully expected a failure to even "ker-chunk" the .900 machine. To my immense surprise, the signal came back at S9! Still, there was no way that I could reach the 224.94- repeater in New Brighton...was there? Yeah. I got an S6 from it.
This was starting to get exciting! As I got on the I-394 frontage road, the 224.94 was now about S8, and I even got an intermittent S3 from the .880 in Maplewood. Even better, I heard no intermod at all. Satisfied that I was actually getting out, I threw out my sign on the 223.940 HandiHam repeater in hopes of getting a signal check. Just because you can "ker-chunk" repeaters, that doesn't mean that you're readable.
And so I got another surprise. WA0RA (Ron) came back to my sign, and he was on the 220 side. The 223.940- is cross-band linked to the two-metre 145.450 and a few UHF repeaters, and I expected to get someone on one of the other bands. Instead, I got a great test of my reach in to the repeater in Arden Hills. The 223.940 was S9, of course, and Ron said that I was full-quieting into it. It was "only" 12 miles away, but it would be a stretch to call my rig "modest", too.
I stuck with Ron on the 223.94, half-believing that I'd drop out as I worked my way through the hills and valleys of New Hope. As it turned out, Ron had just got a 25W Alinco monoband mobile and had an exterior J-pole set up. As he was in Blaine, he was blasting into the Arden Hills repeater at full power, but he soon dropped down to 10W. We have a new operator on the local 1.25M band, and that's good news. I'll have to try some FM simplex with him when I run into him on the local repeaters.
Overall, my new antenna has worked really well. Driving around Plymouth, I'm getting great signals from the local 1.25M repeaters. My goal is to use my TYT HT as a 1.25M mobile to access the HandiHam network when I switch to a full-powered UHF monoband rig soon. It sure looks as if I'll be able to reach the 1.25M HandiHam repeater easily from this side of town. If you've got an HT for the 1.25M band, you might be surprised what you can do with a home-made 1/4-wave ground-plane or a J-pole.
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