[Milsurplus] RT-907/PPN-17 radar transponder

Wed Apr 24 14:31:47 EDT 2013

Courtesy of Mike Hanz. The first paragraph may have been posted here before:

AN/PPN-17 Transponder Set:  Under a contract with RADC, Avion
Electronics, Incorporated developed and produced the AN/PPN-17
transponder for use in Southeast Asia as a portable navigation aid
during night or conditions of low visibility.  By May, Avion
Electronics had produced 19 units for evaluation.
Further, from an Air Command and Staff research paper on Khe Sanh & other 'Nam battles:
'radar control beacons had been installed at both Khe Sanh and Con Thien to help guide the attack aircraft 
into the valley and allow them to drop their ordinance much closer to friendly positions in all types of weather 
and during limited visibility.' This was in the period 1967-8, which fits with my unit's 1967 contract date. 
Since attack aircraft also carry radar, it might be assumed that the author is talking about the RT-907/PPN-17.
Jack

________________________________

Message: 3
Date: Wed, 24 Apr 2013 00:34:45 -0400
From: Peter Gottlieb <nerd at verizon.net>
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] RT-907/PPN-17 Radar Transponder
Message-ID: <517760E5.8040603 at verizon.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I saw it and was considering picking it up them remembered I have yet to find 
info on the one I already have.  Very cool device inside, very compact for its 
time.  I don't have the battery pack and mine is a little rougher looking.  Let 
me know if you find out anything.

Peter

On 4/24/2013 12:25 AM, Jack Sullivan wrote:
> I picked this upon eBay but have yet to find any info on it. From the 1967 contact code I could guess it was likely for use in the 'Nam, possibly for clandestine ops. Anyone have any info, manuals, etc?
>
> Thanks!
>
> Jack
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1432 / Virus Database: 3162/5768 - Release Date: 04/23/13
>
>

------------------------------

Message: 4
Date: Wed, 24 Apr 2013 09:02:25 -0400
From: Mark K3MSB <mark.k3msb at gmail.com>
To: List Milsurplus <milsurplus at mailman.qth.net>
Subject: [Milsurplus] AN/SRT-10
Message-ID:
    <CABdVoaBxP5A1b6WjHrePc8BPN1FZnn3ZDEeBUe0Hg9=-_Fhdjg at mail.gmail.com>
Content-Type: text/plain; charset=windows-1252

Does anybody have any information regarding how and when the AN/SRT-10
transmitter was used?   I picked up one of these about 6 years ago along
with the power supply but can find no information on the web about this
radio.

I have the original manual TM 11-837 so I know the technical specifications
and that there was a land and ship based version of the radio.   Aside from
that I can find no information regarding usage.

My TM 11-837 version is dated July 1951 and it states it supersedes the May
1945 version, which indicates this is of WW II vintage..

This would make an interesting radio to do some low band AM as it covers
160 through 40M with a pair of 807?s in push ? pull.  That?s about 50W
output;  not for casual driving on 75M at night,  but ought to do just fine
for 40/75 during the day.

I have some photos at http://www.k3msb.com/t240/t240_srt10.html

Thanks & 73

Mark K3MSB

------------------------------

Message: 5
Date: Wed, 24 Apr 2013 09:23:03 -0500
From: "David Stinson" <arc5 at ix.netcom.com>
To: "ARC-5 List" <arc5 at mailman.qth.net>, <milsurplus at mailman.qth.net>,
    <boatanchors at theporch.com>, <boatanchors at mailman.qth.net>
Subject: [Milsurplus] BC-348 Backlash Suggestions
Message-ID: <EF6E31C6015D4FB2873BAF8CBA86BEFB at CompaqSR5710F>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
    reply-type=original

Been reviving a BC-348 for a friend.  
It had a "doofuss-try" I hadn't seen before- 
someone rotated the bandswitches 180 degrees.  
Didn't know you could even do that.

After this and lots of other work, it's playing well
and is one of the best sounding 348s I've ever done. 
Even the crystal filter works well.
One common problem remains- tuning backlash.

The three major contributors to backlash in a 348 
are the tuning capacitor gear, the worm wheel and
the worm shaft.  Here is a photo:

http://home.netcom.com/~arc5/348gears.jpg

First, make sure all the gears are clean and lubed.
Put some drops of GOOD penetrating oil 
on the edges of each gear and let them sit.
Do this until the two halves of the gears 
move freely.   You can test this with a small
screwdriver inserted between two edge teeth.
Mesh the teeth and they should spring back.

The gear on the end of the cap is not too tough
and that's good, since it's usually the big baddie.
Just takes patience and practice.  Close the cap all 
the way and make sure this coincides with the end
stop on the tuning knob.  Loosen the two screws on
the gear end, but don't remove them.  You want to be 
able to disengage the gear from the pinion, but just barely.
This is best done at a 45-degree angle toward the front.
I use a pair of hemostats to engage both sides of the 
gear and well-compress the spring.  
Then, making sure the tuning knob is still on the stop 
and the capacitor is still fully meshed,  
re-engage the gear and tighten the cap back down.

The parts where I could use suggestions.
The worm gear wheel also needs to be retensioned, 
but the assembly is pinned together and the ends 
of the pins "boogered-up" so you can't drive them out
without damaging the whole assembly.

I can't disengage the worm gear wheel to retension it 
like the cap gear, nor can I remove the worm gear shaft, 
as it is also pinned.
In the past, I've used hemostats to removed one of 
the worm wheel springs, stretch it out, try to put it back, 
cursed at the 27th try, then watched the spring 
"sproing-ing-ing" off into oblivion,
found another spring in the junkbox, 
stretched it too much so that, once I did get it on,
it stuck -out the sides of the gear etc. etc.

And then there's the worm gear shaft- 
this problem is nasty and is also common on later production 348s.  
The worm shaft slops "in and out" towards the back and front.
Common symptom is "wibble-wobble" while tuning
that is most pronouced on the higher bands.
The shaft has a wimpy leaf spring under the worm
and a felt pad under the tuning knob that help some,
but it's no cure.
I cannot remove the worm to add a washer or bearings
under it.  Only someone with an advanced machine shop 
should attempt it since you will absolutely wreck the thing 
if you try to hammer and whack the pins out.
So I'm looking for suggestions on how to address
the slop in these two gears.

How about a couple of snap-rings under the worm shaft?

TNX ES 73 DE Dave AB5S

------------------------------

______________________________________________________________
Milsurplus mailing list
Home: http://mailman.qth.net/mailman/listinfo/milsurplus
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Milsurplus at mailman.qth.net

End of Milsurplus Digest, Vol 108, Issue 39
*******************************************