AS-1729 Antenna on the M-715

[rboltz]

I have had a few questions both recently and in the past about the AS-1729 antennas. Since I documented my installation, here is probably more then you wanted to know;

The AS-1729/VRC antenna and mount as installed on the M-715

The AS-1729 antenna system was designed for the VRC-12 series of radios and was in use prior to the introduction of the M-715. These antennas were first installed on the M-37 and M-35 series of trucks as well as others, mostly replacing the AB-15 type mounts used with the GRC series of tube radios. When the M-715 came along, the same installation kits were used as designed for the other trucks. I am not aware of a custom kit specifically for the M-715’s though there may have been one. Even the instructions in the kits referred to other trucks but were unit and depot installed on the M-715’s in the field. The most common mount for the antenna is the one commonly called the “sugar scoop”. This mount was adapted to the M-715 and many other trucks. This mount is the focus of this discussion.

Shown in the first picture are the contents of my installation kit. The kit number label was no longer on the box so I don’t know what it was. The kit includes;

SC-D-189023 Support Assembly (“sugar scoop” where the base mounts)
SC-C-189025 Bracket (Support Assembly mounts to this)
SC-B-189026 Reinforcement (placed inside the bed and bolts through to the Bracket)
Hardware – 2 bags
Instructions



The Support Assembly is aluminum and the other parts are steel. Interesting to note is the 3 main mount pieces in my kit were all different color paint. The support assembly was CARC, and the other 2 pieces were of different shades of OD. I repainted all 3 pieces to match my truck but in reality, accessory truck parts seldom matched during my Army days. Maybe different manufacturers of each part or the kits were built from parts on hand. The fact that many truck parts did not match has been discussed here on the Zone many times. Also, the hardware kit is chromate plated, not painted. One set of hardware is 5/16 NF for the Bracket and Reinforcement attachment, and another set of both ¼”NC and ¼”NF for the Support Assembly to the Bracket. Why both NC and NF sets is unknown since you only need one set. Must be to give the installer a choice or there may have been unit requirements. I chose not to paint the hardware for my installation.

There are toothed washers provided for both between the Bracket and the bed and under the nut at the Reinforcement. If you are going to use the antenna, as I am, these provide the bite needed for a good ground. You do not put a washer under the bolt head. For the Support Assembly attachment, you use a toothed washer under the bolt head and under the nut. The instructions show the location for the M-37 and M-35 and similar locations were used on the M-715. The most common is on the curb side of the cargo bed, ahead of the rear fender. When my truck was media blasted, the holes for the mounts were discovered in this location. A previous owner filled the holes with body filler.





The antenna consists of three main parts and the rope and tip;

MX-6707 Base
AS-1730 Lower Element
AT-1095 Upper Element



The base attaches to the Support with 4 bolts and toothed washers. It is rotated to a positioned so the switch on the bottom is accessible from the front. The antenna sections are screwed together and screwed into the base. A tip, rope and clamp kit come along with the set to prevent tip damage and to tie the antenna to the front bumper to lower it.




Technical Info;
The antenna is really a vertical dipole although they called it a whip. The upper section is the radiating element and the lower element is the matching section. The base contains an impedance matching antenna tuning unit that operates both manually and automatically and is broad tuned in bands. It will try to match the 50 ohm radio to the antenna all across the band and will obtain a worst case SWR of 3.5:1. The AS-1729/VRC has been replaced by the AS/3900A/VRC.

[randyscycle]

Very neat info to know! That is the exact same antenna I have on mine, but I don't actually use a radio.

I studied a lot of pictures to discern which antenna looked correct, then went with that one. Looks like I was right!

[brute4c]

Great anntena info...thanks for the write up and pics!!

[Kaiserjeeps]

I just logged on looking for this specific information since I asked last week. Absolutely great and thorough post! It's good to see the kit's so a guy can try to assemble one if they are not to be found. Thanks for a great post. This kind of stuff is priceless info.

[oddave]

Any reason you couldn't move the antanae on the passenger side back to keep the added gerry can? I am thinking of installing this setup on my truck but, don't want to loose the extra can as the bracket is already mounted.

[rboltz]

Any reason you couldn't move the antanae on the passenger side back to keep the added gerry can? I am thinking of installing this setup on my truck but, don't want to loose the extra can as the bracket is already mounted.

No reason electrically or mechanically, just authentically. Many trucks, including mine, came with the holes already drilled at the location shown.

[Beast]

Any reason you couldn't move the antanae on the passenger side back to keep the added gerry can? I am thinking of installing this setup on my truck but, don't want to loose the extra can as the bracket is already mounted.

There is plenty of room to do it. My truck had the holes far enough back that it cleared the extra jerry can. Since most of these were added at a motorpool level almost any thing can go. It makes me think that the extra can mount was added sometime during it's military career and the anntena mount was positioned to acomadate it.

[militarypotts]

I also have the same set-up. The only difference being that I always tie my antenna facing the back of the truck. I worry that while driving the forward bend might catch a low tree branch. All a matter of personnal opinion I suppose. My whole antenna setup came off a military base in Isreal! Weird but true. I spent 6 years in the Army as a truck driver mechanic in the motor pool, but just can't remember ever having a M715 with a radio mounted to it. Maybe my memory isn't serving me well. Anyway, the antenna gives the truck a nice look I think.