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THE AM BULLETIN BOARD => Military Amateur Radio Section => Topic started by: Opcom on March 28, 2020, 08:34:38 PM



Title: Does anyone know what frequencies this military antenna is designed for?
Post by: Opcom on March 28, 2020, 08:34:38 PM
This is probably VHF, since HF stuff is bigger on aircraft, but I don't know. It would like to repurpose it. It is a weird one.

ANTENNA, FM HOMING (LH)
BHC PART No 206-d75-523-1
P.O. No T40000-003
CCC PART No FMH 10-36-1
COMMUNICATIONS COMPONENTS CORPORATION
LONG BEACH, CALIFORNIA


Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: KA0HCP on April 01, 2020, 03:32:55 PM
It would have to be an Army antenna for the military VHF-LO frequencies.  Wikipedia/Google will quickly yield the frequency plan.  (Around 49Mhz off the top of my head).   bill


Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: Tom WA3KLR on April 01, 2020, 07:42:47 PM
The d in the part number looked like a zero to me.  Putting in that number on the google search I came up with a Bell OH-58A Kiowa helicopter manual listing that FM homing antenna on the equipment list.
I think starting with that, you can find out more.  The (LH) may refer to left-hand, perhaps one on each side of the nose or tail. The antenna kind of reminds me of the aircraft 75 MHz marker beacon antenna which I think was a little shorter (an AM signal system).  So the 40 -50 MHz region guess seems to be a good one.

Good luck.


Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: Tom WA3KLR on April 02, 2020, 02:30:57 PM
 I found this manual on the web - TM 11-1520-228-34, 85 pages, shows the antennas oriented vertically on each side of the helicopter, just behind the rear cabin door.  


Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: Tom WA3KLR on April 03, 2020, 08:15:53 PM
After skimming through the manual again this evening, I spotted a drawing showing the cables from the two homing antennas going to FM no.1 and FM No.2 radios, not to the VHF Command radio as I said earlier.  This VHF FM radio does the secure communications also. It is AN/ARC-114 which covers 30 - 75.95 MHz.


Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: Opcom on April 07, 2020, 02:15:41 AM
Wow thanks!!

Two identical ones, alas.. not one for each side. still, 6 meters is a possibility and they were free..


Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: KA3EKH on April 07, 2020, 11:25:05 AM
Couple years back at Gilbert (MRCA) one of the group members set up a display of the military tactical band homing system that I think used the same antennas and a relay assembly that allowed you to home in on a signal from an aircraft. Think it was a big thing after WW2 before the wide deployment of TACAN systems. Maybe big in Korea, by Vietnam they had mobile TACAN in truck mounted shelters so when you needed to find home you can use that.
 I stole this picture from the internet of the AN/ARC-44 and that’s the radio it was used with. Just above the control head you can see the relay assembly. I was particularly impressed to see a old radio like the 44 in operation being it’s a way difficult to make and keep working especially with the DF stuff.
The ARC-44 is a much unloved set and can be purchased for just about nothing so maybe you can build up the complete set?




Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: Opcom on April 08, 2020, 01:34:04 AM
Seeing the antenna is for the low VHF military band, I already have too much gear on those frequencies to need more!! I like a challenge but have too many already.

PRC-77
PRC-25
TRA-967 (Racal), two.
RT-246
RT-524

Not sure what I will do with them, sold off my military trucks. At my age, only the Racals are light enough to lug around.

Currently:




Title: Re: Does anyone know what frequencies this military antenna is designed for?
Post by: KA3EKH on April 08, 2020, 09:06:10 AM
A PRC-68 or 128 would fit a lot better! although the 77 is eraser to work on.
Trying to remember how that DF system worked, from what I recall when using it if you were heading towards the signal it produced a study tone and if off to the right or left it was like a A or an N and just by using your ears  and the two DF antennas with the relay you can home in on the transmitting station.

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