AB15 installation on an MP50 mount

Jake266 · Post by **Jake266** » Fri Oct 27, 2017 11:27 am

After a very long time in the shop, I finally have my M38 back home. I removed the AB15 from the mount before she went in for repairs but for some reason, I believe I'm missing a washer for reinstall. Can someone please show me where each washer and the rubber washer go on the MP50 mount? Living in the country I need to have the antenna on and up so people don't run over me on the roads. The flag at the top kinda sticks out, I hope.
Thanks for any help anyone can supply.[/i][/b]

Post by **wesk** » Fri Oct 27, 2017 12:16 pm

Detail C in this drawing doesn't show any washers between AB-15 and MP-50.

View larger version: http://willysmjeeps.com/v2/modules/gall ... _28605.jpg

That only means the AB15 when installed on the MP50 doesn't require any separate washers on the radio set instructions. The washers you are concerned with may only show up on a detailed parts list or drawing for the AB15 specifically. You need a copy of the Parts List for the AB-15/GR antenna base. TM 11-5985-230-14P.

http://www.liberatedmanuals.com/TM-11-5985-230-14P.pdf

GASKET NO-REF-DESIG 3 X 1-29-32 X 1-16 IN. Ref Drwg SCD12520-2 (80063) NSN 5310-00-189-8907 PN SA212 (Entron Industries Lp) or PN HP8009 (Henry Products). Specs below:

5310-00-189-8907, 5310001898907 Characteristics Data
MRC Criteria Characteristic
AAGR CROSS-SECTIONAL SHAPE STYLE RECTANGULAR
AAUB HOLE DIAMETER 1.906 INCHES NOMINAL
ABMW PERIPHERAL SHAPE STYLE ROUND
ABMX CENTER HOLE SHAPE STYLE ROUND
ABNM THICKNESS 0.062 INCHES NOMINAL
ADAV OVERALL DIAMETER 3.000 INCHES NOMINAL
CQBC III MINIMUM TENSILE STRENGTH 1 POUNDS PER SQUARE INCH
CQFM HARDNESS RATING 35.0 DUROMETER MINIMUM AND 45.0 DUROMETER MAXIMUM
MATT MATERIAL RUBBER SYNTHETIC OVERALL
MDCL MATERIAL DOCUMENT AND CLASSIFICATION MIL-R-3065 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL

radtech · Post by **radtech** » Fri Oct 27, 2017 2:15 pm

Rubber seals go between the ceramic elements and the MP50.One on the top and one on the bottom half.If you have the grounding disc with strap and hose clamp that goes around the antenna connector then the grounding disc goes against the MP50 and the rubber goes between the grounding disc and lower ceramic section.

Post by **wesk** » Fri Oct 27, 2017 2:44 pm

Good point Radtech. The clamp/ring and strap are part of the terminal adapter UG-273/U.

One problem if you do not already have the clamp ring and starp, the replacements available seem to not include the clamp/ring and strap.

UG-273/U
NSN: 5935-00-149-3534
Also manufactured under the following part numbers... 0906-0310, 10519439, 11368, 1250-0071, 1703, 2413, 24339 24006, 29JP100-1, 29JP100-2, 31-028, 31-028-1020, 357-6632-010, 4000, 4101320-005, 470-2, 588A18, 5900007-0000-000, 7124872P1, 73-90910-4, 7601754, 888997-4203, A50731, IS000177, MILA27434, MS90577+273, MS90577-273, N17C67988-5260, P250A4063, RE49F389, RT510-075.00, UG-273/U, UG273U
Exact style may vary between manufacturers
Mil-Spec Grade components are manufactured to a higher specification for military use.

radtech · Post by **radtech** » Fri Oct 27, 2017 5:30 pm

The UG-273/U with the ring and clamp was not used in some installations that used the W-128 wire and not coaxial cable.The ring and ground clamp were not issued with every AB-15.It just grounds the shield layer of a coaxial cable and is really not necessary for the operation of a radio set.

Jake266 · Post by **Jake266** » Sat Oct 28, 2017 7:32 am

Thanks everyone for your replies. I have only 1 neoprene washer and the other one is metal. I do have the grounding piece also. Guess I have to find another neoprene washer somewhere. Wes, the drawing you included really helps, thanks.

Post by **wesk** » Sat Oct 28, 2017 9:14 am

If you are using shielded coax do use the ground clamp/ring. It may not be needed for radio ops but it is needed for completing the needs of the shield to help prevent unwanted radio noise.

Post by **wesk** » Sat Oct 28, 2017 9:41 am

Here's another helpful drawing I've edited to show the VCR style hookup to the coax.

Jake266 · Post by **Jake266** » Sat Oct 28, 2017 1:57 pm

Wes,
Everything will be reconnected and the grounding strap will be attached. Just gotta find a neoprene washer or I'm sure the ceramic will break or crack against the steel. Thanks for the additional drawing.

radtech · Post by **radtech** » Sun Oct 29, 2017 9:31 pm

Which radio set will you install?

Jake266 · Post by **Jake266** » Mon Oct 30, 2017 9:21 am

Radtech,
At the moment all I need is the antenna back in position so I can raise it while driving as an extra protection on our country roads. The colors I have attached to the top of the antenna hopefully give other drivers a clue there is something moving slower than 55mph just over the next hill.
Eventually I will reinstall the radio and power supply. The PS is a PP-112/GR
but not sure about the radio itself. I can't get to it at the moment as some equipment is blocking my access and doc says no messing with it for another week or so. I remember it's an R/T made by magnavox (had a great receiver by them way back when that could blow the roof off a house).

radtech · Post by **radtech** » Mon Oct 30, 2017 9:39 pm

RT-66 20-27.9mc,RT-67 27-38.9mc,RT-68 38-54.9mc.I have been restoring and repairing pre WWII to early Vietnam military radio gear for 45 years.

Jake266 · Post by **Jake266** » Tue Nov 07, 2017 11:35 am

Radtech,
It's an RT-68. I finally made a gasket from a tire patch today I couldn't find a neoprene sheet but the fella at the auto parts store came up with the patch idea. Removed the 1 I still had and used it as a template to cut a new one. Now, once it warms up and drys off a little I will be able to run her into town. It's just the 3 miles on the 2 lane highway that can be dangerous, hence the reason for the antenna with the colors fixed to the top.
Thanks again everyone for your advice.

4x4M38 · Post by **4x4M38** » Tue Nov 07, 2017 5:31 pm

Way to think outside the box!