Commercial whip antenna on ham bands

[alexgeo]

I recently acquired an Icom IC-F70T portable and included with it was a high-gain whip antenna designed for the 150-160Mhz commercial band. Icom does not make a high gain antenna for the amateur bands and its hard to find any antennas that fit this thing without using an adapter.

Can I just continue to use this antenna? I know SWR's tend to be higher on portable antennas to begin with so it's probably not the end of the world. Icom does make a smaller rubber duck antenna designed to cover the entire VHF band, but I question if I'm going to gain any advantage by sticking that on the radio instead...

 

[WB9YBM]

The only two options that come to mind is to either physically change the length of the antenna, or get an antenna tuner--although depending on the type & quality of the tuner, that might not be the easiest/best way to go.

 

[mmckenna]

Hand held radio antennas like that usually provide less than idea SWR in perfect conditions. There's a number of variables involved:
-length of antenna
-proximity to your body
-Counterpoise provided by you holding the radio
Your only -real- control is over the length of the antenna. Even then, 146MHz probably isn't that far out from where this antenna is centered.

Also, hand held radios tend to be very tolerant of changing conditions. It's not going to damage the radio to be operated outside the exact specifications of the antenna like that.

I've run a lot of radios with less than ideal antennas, including radios with antennas designed for the 150MHz range on 2 meter frequencies and never had one fail.

Yes, in an ideal world, you'd get an antenna that was perfectly tuned for the 2 meter band. But don't get too hung up on it. If the radio does what you want, enjoy...

 

[RFI-EMI-GUY]

Well, Some years back, I ordered some OEM 450-470 MHz helical UHF antennas from Motorola for the Saber radios I had in GMRS band. What they shipped had a different part number and it was shown as superseding what I had ordered and what was specified in the manual for the radio.

I did some reception testing from a weak signal and the new antennas were markedly worse than the old cracked ones I had. The new ones were marked 440-470 MHz. I complained to parts department and they put me in touch with the outside vendor who insisted the antennas were being manufactured to Motorola specs and even tested at 414 MHz!! per Motorola 12M specs, which made less sense. They even sent me a few more antennas which were as bad. I think Motorola changed the spec to extend coverage and possibly even sent the vendor the wrong test spec. As it is now, I don't use the helical antennas any longer because they are crap.

 

[alexgeo]

Hand held radio antennas like that usually provide less than idea SWR in perfect conditions. There's a number of variables involved:
-length of antenna
-proximity to your body
-Counterpoise provided by you holding the radio
Your only -real- control is over the length of the antenna. Even then, 146MHz probably isn't that far out from where this antenna is centered.

Also, hand held radios tend to be very tolerant of changing conditions. It's not going to damage the radio to be operated outside the exact specifications of the antenna like that.

I've run a lot of radios with less than ideal antennas, including radios with antennas designed for the 150MHz range on 2 meter frequencies and never had one fail.

Yes, in an ideal world, you'd get an antenna that was perfectly tuned for the 2 meter band. But don't get too hung up on it. If the radio does what you want, enjoy...

That’s what I was thinking. A whip antenna is already a compromise...guess it doesn’t really matter if it’s not perfect.

I notice that you live in SC. I went to school there! Does SCPD still use analog PM1500s? Along with Santa Clara sheriff seems like they were one of the few remaining agencies in the Bay Area using VHF.

 

[mmckenna]

That’s what I was thinking. A whip antenna is already a compromise...guess it doesn’t really matter if it’s not perfect.

Yeah, I have a Kenwood TK-5210 that's my 'shop' radio. I have some ham stuff in it, and I've played around with various antennas. I have one of the Kenwood "broad band" antennas that's rated for 140-170MHz. Can't really tell the difference between that one and the stock 146-162MHz antenna.

I notice that you live in SC. I went to school there! Does SCPD still use analog PM1500s? Along with Santa Clara sheriff seems like they were one of the few remaining agencies in the Bay Area using VHF.

Which school did you go to?

I think they still have a few PM1500's. Haven't looked in one of their cars in a while. They do their own radio thing. County uses XTL's. They are still 100% VHF analog, but going to P25 soon, like everyone else.

 

[alexgeo]

Which school did you go to?

I think they still have a few PM1500's. Haven't looked in one of their cars in a while. They do their own radio thing. County uses XTL's. They are still 100% VHF analog, but going to P25 soon, like everyone else.

I went to UC. I worked for the IT department nearly 4 years while I was there. Regularly had an NXDN portable strapped to my hip when I was doing computer lab upgrades and repairs in the summer. Good times!!

 

[mmckenna]

Ah, very familiar with that system. I sent you a PM.

 

[francisuk29]

I recently acquired an Icom IC-F70T portable and included with it was a high-gain whip antenna designed for the 150-160Mhz commercial band. Icom does not make a high gain antenna for the amateur bands and its hard to find any antennas that fit this thing without using an adapter

I bought many antennas in the past but since making my own i find that getting some high end coaxial cable and cut about 17.5 inches and centre it for around 155Mhz for the 150-160Mhz band, Yes it may cost abit more but in the end result, you get way way better then some crappy eBay antenna