[Motorola] HT1250 VHF Antennas

[Coote, Jay]

Dennis and List,
A full-size, quarterwave VHF antenna would be about 18-19 inches in length.  No one wants that in a handheld radio, so most VHF whips are helical, and only 6-7 inches in length.  The drawback is, antenna efficiency.  A coiled up VHF whip may be 3 to 6 dB down from a full size quarterwave.  3 or 6 dB? No big deal maybe, but in a 5-watt handheld, radiated power would be 2.5 to 1.25 watts.  I noticed that there "stubby" antennas were shown in the link.  If a VHF stubby were even shorter than its 7-inch counterpart, its performance would be worse.  The frequency band of the antenna is important.  The wrong VHF sub-band antenna would also make a difference.  Could be that the radio has a high-split VHF antenna and that you need a 136-150 MHz antenna for what you are doing? It might also be helpful to make side-by-side sensitivity comparisons between the two radio models, with various antennas attached.  

-----Original Message-----
From: motorola-bounces at mailman.qth.net [mailto:motorola-bounces at mailman.qth.net] On Behalf Of Dennis Wade
Sent: Wednesday, October 05, 2011 22:31
To: Discussion of equipment manufactured by Motorola; motorola-Radios at yahoogroups.com
Subject: [Motorola] HT1250 VHF Antennas

Good evening all,

          I'm the recently new owner of a refurbished HT1250 VHF.
Having used a 99 ch MT1000 for a number of years, I loved the
ruggedness of the MT, but really wanted a more modern display, and a
programming system that didn't require me to dumpster dive for a
suitable computer... :).

          I used the HT in an annual public service event during which
I am in places where hitting certain repeaters is sketchy...sometimes
I can, sometimes I can't.  I know about how the MT will perform...this
was my first chance to use the HT.  I noticed a subtle difference in
that the HT wasn't quite able to open machines that I probably could
have the year before with the MT.  However, circumstances prohibited
me from carrying both radios. (I did not notice a similar difference
on the receive side).

          One thing I discovered is that in this
document,(http://www.wiscomm.com/MotoCatalog/HT750-HT1250-HT1550.pdf)
on page 23, it describes various VHF antennas available for the
HT1250.  Only one covers the ham band, i.e. part number 8504762J01.

           I looked to see what I was given with refurbished radio..I
could not find a part number..only "Motorola VHF" embossed in the
rubber cover.

           There really is no clear answer because multiple things may
have changed over the course of the year.  I do have two questions:

                 1.  Could the wrong antenna contribute to the noticed
difference in performance?

                 2.  Where is (or is it important) to find the part
number on the antenna I have?

             and, (I know, this is 3),

                 3.  Are there 3rd party antennas that might perform better?

        Thanks for your help,

                    Dennis



-- 
"If they trust you, it is an extraordinary privilege, and you simply
can't abuse it."
      - A. Alan Post  1914-2011.  California Legislative Analyst 1949-1977.

-------------------------
Dennis L. Wade
KG6ZI
Carmichael, CA
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