Really enjoying this topic, the builds are great, and the spin-off conversations are both informative and interesting, .
A couple of questions if I may regarding Vietnam era sandbags, would they be made from a sacking material similar to those used in WW! & WW2, or would they be made from a different material, e.g. something more capable of withstanding the high humidity without rotting away? Also, would there be a standard size of bag, e.g. being larger or smaller than those used during the two world wars?
From what i have read there are made from woven plastic, canvas and or hessian/burlap bags
I sized mine from a 1/35 scale figure (don’t make em to big)
I am sure somebody will comment with more knowledge
I wonder what colors is was painted in? Being USMC, I might imagine red with yellow (gold) lettering, but traditional USPS overall blue with white lettering could also be a reasonable speculation. It does seem just a tad darker in tone than the brown (subdued red? LOL!) and yellow of the sign also seen in the color photo.
The main SF long range radio set at that time was the AN/GRC-109 coupled with the AN/GRA-71 “code burst device.” (We were still using the AN/GRA-71 until it was finally replaced with the DMDG KY-879 in the late 1980s!)
This set up was classic AM “sky wave” and the GRA-71 used spring driven cartridges of industrial magnetic tape to record the manually inputted Morse code dots and dashes. The spring was wound up as the tape advanced. Once detached from the input device, the spring automatically rewound the tape and the cartridge was then attached to the signal device which was then attached to the radio transmitter-receiver which was tuned to the correct frequency. When the correct time window for the team’s transmission was reached, the “code burst device” was turned on and the Morse code message was transmitted at very high speed (a message of hundreds of 5-letter groups could be set in less than 30 seconds). The signal device with the tape cartridge ran the tapped message at a very high rate of speed. Of course, the messages were also encrypted mostly using a trigraph and one-time pads.
The timing of transmissions and messages to and from the SF HQ base station was according to a strict timetable. Outstations (aka SF teams) had specific windows (usually about 2 minutes long) to either receive or transmit (depending on the schedule). There were a number of such windows scheduled throughout any give 24 hour period. Messages were re-transmitted until the intended recipient acknowledged their receipt. The base station transmitted messages nearly continuously with most of them being things like weather reports so as to not allow the enemy to figure out when they were transmitting to specific teams. The system was intended to mitigate the enemy’s changes of using RDF techniques to locate the teams in the field. The message content was secured through the use of the one-time pad encryption (both transmitted and received messages).
The DMDG (Digital Message Device Group) replaced the mechanical GRA-71 a few years before the use of tactical satellite commo was in use by SF. By that time the radio set had also changed a couple of times to the PRC-74 (soon to be replaced by the PRC-104 at about the same time the DMDG was being fielded, the PRC-104 being designed for transmitting and receiving digital data). Using the DMDG, transmission times were reduced to fractions of a second for enormous data loads. Tuning the radio to frequency was actually more dangerous than the message transmission.
(BTW, the DMDG could also be with any radio, so it was also possible to, for example, transmit text messages over short distances using low-powered tactical FM radios which is a useful technique in some situations.)
Tactical satellite communications were not common for US SF until the end of the '80s into the early '90s. The first TACSAT radio in common use by US SF units was the AN/PRC-117 introduced in the early '90s. It’s still in use today having been modified into versions lettered as high as F and G.
never saw a round bunker in my 15 months, unless it was concrete. Looks like it was like it might be from mid 68 or earlier. Maybe 66, or 67 as you don’t see the purple sand bags in the mix. When I was on Gator, all the bags were similar to the picture. They were stacked in early 67, but when we got new bags there was always a bundle of purple bags in the mix.
The radio antenna gives you a hint of being on a hill top. Who ever built it worked pretty hard on it.
gary
honestly; they were still using a lot of surplus stuff from WWII even in early 68. I was shoot ammo made as early as 1944! By the time TET was over and done with, we were into new lots of ammo. I would say the samething about sandbags. If you were in a rough place, you were constantly replacing sandbags from rocket and mortar rounds (assuming they were filled with sand). We used a lot of clay filed bags, but still filled bags with sand and gravel all the time. A clay filled bag will take ten times the punishment a sand filled bag will
gary
we operated in deep valleys and mountain tops. Seemed to be no in between. They were on a recon mission, and contact was not a wanted thing. The NVA were pretty good at jamming radio frequencies by simply broadcasting Vietnamese music! The new radios seemed to be jam proof for the most part. They also used direction finders a lot (we did to) to try and find your location. When you were way out west (on the border) everything seemed to get jammed. The sorta fixed this with a C130 relaying data. This is one reason why fire bases relied so much on hard wired field telephones. They’re jam proof
gary
Hi Piet . Captions on your photo read Khe Sanh , Jan. 1968 , according to poster on Pinterest .
Two more photos that I believe are the same bunker .
Sorry , can’t find any construction info .
According to a caption I’ve found for the above pics, they show the [1st Battalion, 26th Marines] Bravo Company command post and connecting trenches at Khe Sanh Combat base in March 1968…
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