Funny how this hobby works. One day I was struggling to get signal out while commuting. The next day I find myself with not just one, but two mobile antennas.
Last week I ordered an MFJ 1724B dual band quarter wave mobile antenna with mag mount, and a UHF to SMA jumper cable to adapt it to my HT. Yes, I know, to some, MFJ = Mississippi’s Finest Junk. But I figure it can’t be that junky if it were recommended by one of our emcomm gurus on the local EARC net. It came in the mail on Saturday.
That Saturday was also the day of the ham swap meet over at Aiea Elementary. One of the finds I found (besides a free roll of antenna wire) was a Workman KS1SMA quarter-wave rare earth magnet mount dual band mobile antenna. Only $15.
What a difference getting the metal outside the vehicle makes! I was able to hit the 146.88 repeater from just outside the Honolulu-bound Pali Tunnels! Yes, that far into Nuuanu Valley. On the HT from in the vehicle, it would have been a 50-50 shot from the Queen Emma Summer Palace.
Right now I’ve been operating my base off a half-wave dual-band, a Diamond NR73BNMO on loan from Ron (AH6RH). I’ve been able to get good results on 146.88 on 10-20 watts from Kailua (pretty good, considering I’m operating it indoors right now and having to hurl the signal over the Koolaus to get to Diamond Head).
Alas, all good things come to an end; Ron wants his antenna back (along with the speaker and the SWR meter) so that he can give a full rig to another new ham.
Fortunately, after several tries I was able to jury rig the 1724B with a ground plane to give an acceptable SWR (about 1.7). Let’s just say that it involved a pizza pan and a whole lot of aluminum foil. So now I have a substitute base in my 1724B and the KS1 is atop my vehicle. Eventually I’m going to need to find a place to mount a permanent antenna. I’m thinking about mounting it off one of the eaves. But we’ll see.
Hi Keith! Found the blog! Love it! I’ll be checking in fromtime to time so keep up the great work! Aloha, -Rich
Hi Keith_
Just wanted to let you know the ground plane for any antenna requiring a ground plane. It should be about 5 per cent longer than the 1/4 wave vertical. Too much ground plane length will cause the antenna radiation characteristics to go bonkers. It would be ok to use ODD multiples of 1/4 length ground plane (like 3/4 wave length ground plane) for example. But the radiation pattern will change. I believe if I used a 1/4 wave length vertical with 3/4 wave length ground plane, I might even get 1 to 1 SWR. But the antenna’s maximum radiation will have a higher take-off angle than that of a 1/4 wave length vertical sporting a 1/4 wave length ground plane. But then, maybe that might be just right for working hams at higher elevations than my location.
I hope I’m not telling you something you already know.
73,
Bob KH6ZZ, Antenna Freak