[Milsurplus] TCS Antenna advice

Tue Jun 17 01:20:25 EDT 2008

Jim and Robert,
  I was under the impression,from on line conversations some years back, 
with PT Boat crew members,that the PT whip was solid Monel, about 20 ft 
long.The ground was probably a hull mounted plate back near the shafts 
so as to always be in the water.My uncle, Commander Richard 
Lamborn,deceased, could have told us all...Sadly I was too young to ask.
  A large number of PT's were burned en masse in the Phillapeans when 
the war ended, including my uncles.A dive on the site may render 
clues...but who has the dough to go and look?
  The last time I had my TCS loaded it worked fine into a 60 ft long 
wire on 80 meters with a good copper rod 6 feet under.
 Jim,
  you saw how poorly my TCS worked at MRCG 2007! De-Oxit is the cure but 
with careful application.
 Jay KE6PPF

-----Original Message-----
From: WA5CAB at cs.com
To: mcenfalz at humboldt1.com; milsurplus at mailman.qth.net
Sent: Sun, 15 Jun 2008 10:23 pm
Subject: Re: [Milsurplus] TCS Antenna advice

Jim,

You've run into the quandry faced by all of the WW-II vintage sets that 
used open wire from the radio to the antenna.  However, I've never 
heard of a "standard" 20' whip antenna.  I've seen reference to a 16' 
whip used on small craft.  But I don't know of anyone who ever acquired 
one.  And there may have been a 25' whip, although I can't recall where 
I saw the reference.  The standard Navy shipboard whip antenna is (or 
at least was when I left the Blue Water Navy and transferred to the 
Mine Force in 1975) 35' tall and about 2" or 3" in diameter at the base 
insulator.  Generically referred to by all hands concerned with them as 
35' whips.  An Essex Class Carrier would have had maybe two dozen of 
them in fixed mounts on the island structure and on fold-over mounts 
along the flight deck edge.  FRAM-2 DD's had maybe eight.  I never 
served on anything in between.

TCS's modified for submarine service have Type N connectors on the 
front panel and a different antenna loading coil unit also equipped 
with N connectors.

In Army vehicles early to mid-War, the length of the antenna (number of 
3' mast sections used if the radio was VHF) was adjusted for the 
feed-line length inside the vehicle.  After which, conversions to 
coaxial cable became more common.

The two TCS on USS Valley Forge were both located in the island 
structure and fed wire antennas of about 30' length.  And can't recall 
the details of one of them but the one I often played with had about a 
10' feedline supported on stand-off insulators to a feed-through 
insulator on the starboard bulkhead.  The antenna was connected to the 
outer end of the insulator.  Coincidentally, that's about the same 
antenna that I have here.  Except that the antenna portion is nearly 
horizontal instead of nearly vertical up to the yard-arm.

In a message dated 6/15/2008 11:38:59 PM Central Daylight Time, 
mcenfalz at humboldt1.com writes:

I am trying to approximate the vertical antenna system a TCS drove 
while in typical service so as to maximize its output. From what I have 
collected online from PT Boat and Landing Craft sites, looks like the 
radio sat on the side closest to the antenna trunk (~8 " square 
vertical metal conduit w/feed line centered inside it). These trunks 
were located next to the conn/bridge and look similar to what I have 
seen in photos of the LCI(L)-1091. Both had a fat isolator/antenna 
mount at the top of the trunk to support the whip.

However.......as I understand these beasts from prior discussions on 
this forum, the TX expects the antenna to begin at the antenna lug on 
the exterior of the case. So, my quandary: if this thing was designed 
to drive a "20 foot whip" what about that extra cable running from the 
TX to the trunking and up to the antenna? Is there an optimum feed line 
length? I have not found anything in my TCS-13 manual as to 
onboard/vehicular mounting regarding whips and feed line configurations.

On the LCI(L)-1091, I understand that the feed line was a fat, 3/4"-1" 
wide strap of copper braid that went from the TX in the radio room up 
the interior wall to several insulators on the ceiling, forward most of 
10-15 feet into another cabin, then up thru the deck another ~15' 
inside the cable trunk that ended near the top of the bridge/conn, and 
then into the famous 20' whip. By definition, you had RF in the shack 
and a 50 foot inverted-L "antenna" partially enclosed in a steel box.

I ran mine at a local air show last week using a 16 foot whip and 15 
feet of feed line (RF safety) in conjunction w/ a single 1/4 wave tuned 
counterpoise expecting great results, but the thing only indicated 0.7 
RF A at best. It supposedly should run closer to 1.5 A. When hooked 
into my old OCFD (pseudo-Windom) via T network tuner, I would push 1 A. 
Figured the sky was the limit w/the whip.

I tried to "do the right thing" and go vertical w/dismal results. What 
gives?

However.......as I understand these beasts from prior discussions on 
this forum, the TX expects the antenna to begin at the antenna lug on 
the exterior of the case. So, my quandary: if this thing was designed 
to drive a "20 foot whip" what about that extra cable running from the 
TX to the trunking and up to the antenna? Is there an optimum feed line 
length? I have not found anything in my TCS-13 manual as to 
onboard/vehicular mounting regarding whips and feed line configurations.

On the LCI(L)-1091, I understand that the feed line was a fat, 3/4"-1" 
wide strap of copper braid that went from the TX in the radio room up 
the interior wall to several insulators on the ceiling, forward most of 
10-15 feet into another cabin, then up thru the deck another ~15' 
inside the cable trunk that ended near the top of the bridge/conn, and 
then into the famous 20' whip. By definition, you had RF in the shack 
and a 50 foot inverted-L "antenna" partially enclosed in a steel box.

I ran mine at a local air show last week using a 16 foot whip and 15 
feet of feed line (RF safety) in conjunction w/ a single 1/4 wave tuned 
counterpoise expecting great results, but the thing only indicated 0.7 
RF A at best. It supposedly should run closer to 1.5 A. When hooked 
into my old OCFD (pseudo-Windom) via T network tuner, I would push 1 A. 
Figured the sky was the limit w/the whip.

I tried to "do the right thing" and go vertical w/dismal results. What 
gives?

Robert & Susan Downs - Houston
<http://www.wa5cab.com>; (Web Store)
MVPA 9480
<wa5cab at cs.com> (Primary email)
<wa5cab at comcast.net> (Backup email)

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