On my Azden 10 meter FM HT using the stock rubber duck antenna with a BNC connector, when I was transmitting listeners noticed a definate increast in signal when I put my thumb and finger on the BNC connector ground. So then I started carrying a 9 foot long wire connected to an aligator clip which I would connect to the BNC ground and again noticed a definate increase in signal strength.
But certainly you are correct, a low band HT on a rubber duck has poor performance. Despite that, I have worked Sioux City, Iowa to Portland, Oregon several times on my 3 watt HT on 29.6 Mhz. I know that K7LJ has worked US to Japan on his HT-200 (using telescoping antenna) on 29.6 Mhz several times. ------ Original Message ------ Received: Fri, 10 Jul 2009 03:43:24 PM PDT From: Mike Morris WA6ILQ <wa6...@gmail.com> To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Building HT antennas > FWIW I have a 99-channel 42-50MHz MT1000 that I bought with > the intention of using it for both 6m and 47 MHz Red Cross > channels. The radio came with a 32-channel model number, > but the radio took 99 channels just fine. > > The radio is not in service yet as it needs to be modified from > the 42-50 MHz range to 46-54 MHz. > > And I do not know if the radio front end (or the transmit VCO) > will "reach" to both 47mhz and 52-53 MHz. If anybody has > done any work in that direction I'd like to hear from you. > > If it does end up to be usable on both I know that I'm going to > need to have two separate antennas - a shorter one for ham > and a second, longer one, for Red Cross. > > Over the years I've learned that you should not expect any > real transmit performance from a low band HT, especially > an HT200 or an MT1000. Why? > > Two reasons... > > First: > A 1/4 wave at 52 MHz is about 54 inches (about 4 1/2 feet). An > antenna with a decent ground plane would have a 1/4 wave radiator > and a 1/4 wave ground plane, for a total of just about 9 feet long. > I can just see a 9 foot long coaxial antenna plugged into a 7 1/2 > inch long radio. > > Second > The MT1000 uses a hot-only antenna connector, with no ground (at > least the GP68 got that part right). > The only way to get a RF ground is to use a cheezy plastic adapter > that uses an earphone plug to adapt the radio to a length of RG174 coax. > > (see the photos on > <http://www.repeater-builder.com/motorola/genesis/genesis-index.html> > and look above the photo of a hand holding a radio) > FWIW I've seen a couple of the adapters converted to a BNC mounted > into the top of the adapter. > > So without re-engineering the radio your choices are a footlong rubber > duck that would make a good truncheon, or an external antenna. > And the NAB6064B duck is about $24-$25 each. > > More and more I've been thinking that a crossband repeater from a Red > Cross UHF frequency (locally there are several already coordinated, > licensed and in use) to the particular 47 MHz frequency (locally we > have at least three, one of which is the nationwide 47.42) might just > be more practical. > > Mike WA6ILQ > > At 01:42 PM 07/10/09, you wrote: > >Albert, > > > >In the 30-50 MHz band, the antennas for a portable radio must be cut for > >proper operation, over a very narrow range of frequencies. The length of a > >whip antenna must be changed by 1/4-3/8 inch for every 1 MHz. Motorola > >still offers the NAB6064B "tunable" antenna for the MT1000 radio, which must > >be cut to length for the specific frequency needed. In other words, there > >is no such thing as a broadband antenna for low band, and the radio's PA > >could be damaged by using an antenna that is not the right length. The > >NAB6064B antenna costs about $23 from Motorola Parts. Call 800-422-4210 to > >order. > > > >73, Eric Lemmon WB6FLY > > > > > >-----Original Message----- > >From: Repeater-Builder@yahoogroups.com > >[mailto:repeater-buil...@yahoogroups.com] On Behalf Of Albert > >Sent: Friday, July 10, 2009 12:56 PM > >To: Repeater-Builder@yahoogroups.com > >Subject: [Repeater-Builder] Building HT antennas > > > > > > > >Hey guys, I posted this question over on the HT600e forum but didn't get > >anything. I was wondering if anyone here could be of assistance. > > > >I recently acquired a low band MT1000 for use on the 6m band. It has a nice > >new commercial antenna but I was wanting to do something a little better. No > >one that I can find supplies or can supply me with a better antenna for this > >radio. Even smiley antenna, my usual go to company for custom antennas for > >the Genesis line can't help me. So I was thinking of building my own. > > > >My first thought, since the antenna connector on the MT1000 is basically a > >1/4-32 hole, I could thread a piece of aluminum round stock to create a > >base. Then I could just make a 1/4 wave whip from stainless rod. I know it > >would be silly long but it is a start. If I do this, do you think I should > >just use the standard 1/4 wave vertical formula? Would I need to compensate > >for the HT's lack of a ground plane? > > > >Any thoughts would be appreciated. > > > >Thanks > >Albert > >KI4ORI > >
