Question about MP-57 and connecting MS-53

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ziro
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Question about MP-57 and connecting MS-53

Post by ziro » Tue Nov 28, 2017 10:37 am

Hi guys, I couldn't find some information in the TM about my question. For the antenna sections I have the antenna clamps MC-421 to MC-424 to secure the antenna sections together.

Please what happen to the connection of MS-53 to the Mast base MP-57? How is the secure there? In my eyes it make no sense to secure the antenna sections with clamps and to do nothing between base and antenna?

And for what are the two little threads on top of the MP-57?


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Re: Question about MP-57 and connecting MS-53

Post by Radtech » Tue Nov 28, 2017 5:26 pm

The MS 53 screws into the top of the MP57 there was no need for a clamp there. The mast sections screw together and the clamps only keep them from unscrewing.I have been told the holes are there for a special jig used to disassemble the base.The clamps were seldom used as they made it difficult to take down the antenna in a hurry.

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Re: Question about MP-57 and connecting MS-53

Post by cjv-35 » Tue Nov 28, 2017 5:56 pm

I use internal/external star washers to keep my MS antenna sections together. Not factory, but at least they will not come apart.

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Re: Question about MP-57 and connecting MS-53

Post by Mark Tombleson » Tue Nov 28, 2017 9:23 pm

There is also a screw on the side of the MP-57 to hold the antenna section secure.

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Re: Question about MP-57 and connecting MS-53

Post by ziro » Wed Nov 29, 2017 8:05 am

Thats interesting, Mark. My MP-57 has not that big screw. I have only the little ones.

Star washers are not a bad idea! :wink:

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Re: Question about MP-57 and connecting MS-53

Post by John Neuenburg » Wed Nov 29, 2017 6:11 pm

But using clamps is cool if you have them. I'm not doing long road drives with antenna up any more. Had all five up on the M20, tied back, before I started using the clamps. The run included 30 miles of freeway at 48mph. The green one unscrewed and was lost. Tried it another time and the rod came out of the knurled part! My guess is the ones farther down won't tend to unscrew but ???? Moot point, started using the clamps. Then was going to Tower Park with three up, tied back, and #2 broke below the tie back thingy. So it was dragging behind the M20 on the rope - didn't lose it! I was amazed how thin the wall thickness is. This car rides much smoother than a jeep or truck but there must be a lot of action going on with the antenna.
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Re: Question about MP-57 and connecting MS-53

Post by ziro » Wed Nov 29, 2017 10:56 pm

Hi John, good to hear from your little problems. It's good to think about that.

I was very astonished how easy it was to loose the MS-53 from the MP-57. And the thread is not soooooo long that it is not possible to lost it fast by driving. That was the reason for my question. I thought that there is a fixing possibility also. So I have to use tape like they shown as in the TM when you have no clamps?

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Re: Question about MP-57 and connecting MS-53

Post by N6FEG » Thu Nov 30, 2017 5:37 am

Johns comment about the MP 49 coming unscrewed while in transit is the same I've experienced. I guess the gyrations of the antenna while driving tend to have the smaller dia ant sections start to unscrew. For me that was the MP 51- 49 ant's. I used black electrical tape to secure the ant sections from unscrewing. I think it was in the TM for the SCR 506 that it had a photograph showing a GI using , back then, black electrical friction tape to tape do that.

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Re: Question about MP-57 and connecting MS-53

Post by Mark Tombleson » Thu Nov 30, 2017 8:18 am

Several of the used antenna sections that passed thru my hands were sticky on the knurled end area with adhesive that could have been residue from friction tape. I really didn’t think about it.

I must admit the clamps are a pain to install and I always forget to put the clamp for the rope on first.
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Re: Question about MP-57 and connecting MS-53

Post by ziro » Thu Nov 30, 2017 10:47 am

Tape... TM11-630 for SCR-506-A.

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Re: Question about MP-57 and connecting MS-53

Post by John Neuenburg » Thu Nov 30, 2017 11:07 am

Old style friction tape is still available new, for that period touch.
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Re: Question about MP-57 and connecting MS-53

Post by wa5cab » Thu Nov 30, 2017 3:14 pm

ziro,

If your MP-37 is missing the tapped hole for the screw to lock the MS-53 into the MP-57, I would recommend drilling and tapping the hole for the screw. The thread is #10-32 UNF and is located 0.875" (22.22 mm) down from the top most part of the mast base.. Although I don't recall ever seeing an MP-37/57 without the hole, it's certainly possible that one might have slipped past the QA guy. I would drill the first quarter inch or so of the hole with a 3/16" bit. If you do drill and tap the hole, I would recommend running a drill bit the same diameter as the hole for the antenna tip down in the mast section hole after drilling and before and after tapping. A reamer might be better but would be an expensive thing to buy for only one hole, and probably even worse in Europe these days. It doesn't always happen but sometimes when the bit breaks through the inner wall, it leaves some flashing around the hole. A proper size bit carefully inserted by hand into the hole is the best way in which to ensure that if there was any flashing, it is removed. And then blow the hole out after tapping to remove the shavings.
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Re: Question about MP-57 and connecting MS-53

Post by cjv-35 » Thu Nov 30, 2017 4:41 pm

My MP-57 also has NO Screw to lock the bottom antenna section to the collar. IMHO, It has to be a LONG screw to got go through the collar and attach to either the screw treads of the antenna section or the antenna center element. What say's you Robert ?

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Re: Question about MP-57 and connecting MS-53

Post by wa5cab » Thu Nov 30, 2017 8:26 pm

If you look at Mark's photo of his MP-57, you can see that the screw must be pretty long. The tapped hole breaks into the center hole just below the bottom end of the threads. So the screw locks on the ball nose pin that sticks out past the male threads on the bottom end of the MS-53.
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Re: Question about MP-57 and connecting MS-53

Post by ziro » Thu Nov 30, 2017 9:06 pm

Interesting!


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