Military Radio “Field Day” 2018

AFTER ACTION REPORT – Updated 6/3/19

Dateline: 23 June 2018, Forward Operating Base BIGFOOT

The West Coast Military Radio Collectors Group, Detachment ALPHA (FWD) conducted field ops in conjunction with the ARRL Field Day weekend and the 2 days prior, 21-24 June 2018. We deployed to a remote location in the Sierra Nevada mountains of California, about 40 miles north of Yosemite National Park at a favorite spot along a perennial creek.

Spring was just starting to arrive up here in late June, plenty of snow still feeding the creek.

Semi-permanent snow fields

Although our camp was located at 7790 feet elevation, it is in a deep box canyon with 2000 foot higher ridges around 3 sides; NVIS operation was the order of the day. This site is also about 15 miles from the nearest cell-site connectivity and 10 miles from the nearest pavement so HF radio is otherwise pretty valuable out here. Just in case……WiFi? HaHa

The “smart phone drones” would be freakin’ out!! This is why we go here…

We set up operations with the long-range PRC-47 and GRC-9 for SSB and AM voice comms, and the 10 watt TRC-77 and GRC-109 sets for CW. All ops were on 80, 75 and 40 meters plus a VRC-7 and PRC-25 available for local tactical coordination. Antennas included low, horizontal resonant dipoles and the 15 foot whip for the PRC-47 as necessary.

Seven of our usual camping buddies there too, 3 of them are also Hams using 2 meters for convoy and recon ops / fishing SITREPs (HaHa) in the area.


Above: Speaking of signals, the trusty VS-17 Signal Panel helped our inbound camping buddies find our otherwise concealed site in the forest from points along the distant approach route. These things are hard to miss when you want to be seen; don’t leave home without one.

We worked many Field Day stations plus a lengthy round-table chat on the West Coast MRCG AM net on 3985 kc Saturday night with the GRC-9. That net closed and then resumed with many stations also checking in with us on LSB. We had the PRC-47 on LSB, a non-standard for us, as the USB radio was Tango Uniform, but we wanted to work LSB stations during Field Day anyway. (Looks like a USB post-MRCG AM net may gain some traction into the future, SSB worked well for us. 3996 USB on Saturdays anyone?)

We made several daily contacts with Andy during the Thursday and Friday Comm Windows (skeds) prior to the weekend Field Day. His “HQ” station was 158 miles/260 km away in the mountains outside Coalinga CA. He was also running a TRC-77 on CW as well as a URC-58 on SSB plus his BC-610E on AM.

We had very reliable Morse code comms with him as well as later AM and SSB voice contacts. We checked into the Military AM net with the GRC-9 and contacted about 10 AM stations all over California with good signals both ways. Propagation conditions were very good, our 10 watt CW and AM signals were easily making the distance, even the PRC-47 was kept at the 20 watt setting.

Some photos from the trip:

AN/TRC-77 station running solar-charged Gel Cell power

Above: The AN/TRC-77 station set up with a small solar panel to keep its internal Gel Cells “topped off”. Very reliable CW communications on the primary 3550 and 7050 kc West Coast Agent Guard Channel night/day frequencies. This off-grid setup will run indefinitely from The Bush. The TRC-77 was used by the US Army’s Long Range Reconnaissance Patrols, “LURPS”, primarily in Europe in the early-mid 1960’s.
For more information on the AN/TRC-77 take a look here: AN/TRC-77

Field Day 2018 Campsite Radio

Above: The GRC-109 set up outside my hootch. It was powered by that small 12 volt garden tractor battery via my homebrew 12V-HVDC power supply. It ran for days on that battery even without assistance from the solar panel.

The antenna was a 132 foot resonant dipole about 20 feet up between the big pine trees. Rigged quite low, it was perfect for “getting out” of this canyon. The GRC-109 also drove that same “jumpered” dipole on 40 meters with good results.

A reliable field radio in the boonies, as it was intended. It always works. Bullet proof.

Home brew HV power supply

The Mighty GRC-109 powered via the home brew 12 VDC power supply and the garden tractor battery. The ME-61/GRC field strength meter is handy for tuning the transmitter into High-Z antennas, but not necessary.

These sets were used in the early 1950’s by the CIA (as the nearly identical RS-1) and through Vietnam and later by them and the US Army. Many are still cached worldwide, either buried underground or hidden in “interesting” places elsewhere. Just imagine….

For more information on the GRC-109 and its history, take a look here: AN/GRC-109

AN/PRC-47 LSB setup on 24 volt battery power.

Above: The Collins PRC-47 station being set up by the Assistant Radioman in a clearing about 200 meters from our main camp. It was powered by two 12 volt deep cycle batteries in series. These sets were widely used by the US Marine Corps in Vietnam, here in its “peacetime” element. For more on the PRC-47, take a look here: AN/PRC-47

We listened for, and heard, the new Midwest Military Radio Collectors Net on 7296 USB (with a monitor receiver) but their signals were too weak that early in the morning to ID anyone.

If we had the USB PRC-47 working we would have tried checking into the MRCA Moose and Squirrel Net on 5357 kc…..MRCA Moose and Squirrel Net

We have other like-minded operators and organizations. See:

AN/PRC-47 remote station set up next to creek

Above: An HF operating position with a view. Ham radio and remote camping are a great combination! The icy creek is right there, cutting its way through the granite. It sounds just like the “white noise” emanating from the radio speaker.

The mid day propagation over our short 158 mile path to HQ on 40 meters was unusually good for this solar cycle. This no doubt a result of the 10.7 cm solar flux hitting 80 on Friday – the highest so far in a year. That resulted in the NVIS Critical Frequency, fo, being at least as high as 7.3 mc. That enabled very good regional “short skip” conditions that we were planning to use. (By Sunday the flux had dropped to 74, that made a difference.)

Consequently, the stock 15 foot whip antenna made surprisingly good comms out of this canyon for 2 days without the need for the much more effective low dipole. The “up” takeoff angle was probably also helped by the reflective granite canyon walls surrounding us.
RF Boogga Boogga.
The last day, nada NVIS using the whip; back to “normal”; back to the low dipole.

AN/GRA-6 remote control set for the PRC-47

Above: We included the “Control Group AN/GRA-6” remote control field telephone set for the PRC-47 station. H-33 carbon handsets all around. “By the book” deployment – whip, legs, 8 radials deployed. It was about 25 feet from the creek so the “grounding” was good.

AN/GRA-6 remote control at the campsite

Above: The Assistant Radio Operator talking with “HQ” on the PRC-47 radio via the GRA-6 remote control from his hootch – with the radio actually located well back in the forest.

Good contacts were made with Andy at HQ who reported that it sounded exactly like the PRC-47 with its local H-33 handset. This gear works great. We only ran it over about 200 meters of WD-1A/TT assault wire but it is spec’d to operate over 1.6 km of that telephone wire. Very handy!

The GRA-6 also has provision to turn the PRC-47 power on/off remotely, so no local operator at the radio is necessary. Stand your Watch on the Alert Net from the sleeping bag!

It can also be used as a full duplex field telephone between ends if needed. Cool. I have previously utilized it with my VRC-7 FM set which also worked great.
For more information on the GRA-6 system, look here: AN/GRA-6 Radio Wire Integration

Night Ops with the PRC-47

Above: Working the MRCG post-Net with the PRC-47. It’s getting dark, the band is getting long, but we still had solid comms up and down California on 3985 kc with another low horizontal dipole.

The receiver only draws 600 ma and with the low duty cycle of SSB, and keeping the output at 20 watts, these big batteries will keep you going for a week of casual operation at least. The small gas genny was available for recharging, but was not necessary over 4 days. Some say the Tune signal sounds like a harmonica.

Campsite Comms: The AN/PRC-47

Above: Here in its element, the PRC-47 is a capable campsite radio, even with just the whip. Here working K7ZA in western Washington on 40 meters during Field Day. At least a 1000 km shot from here. Good signals both ways.

AN/GRC-9 Mobile installation

Above: Then there’s the GRC-9, permanently mounted in the old Bronco – Always reliable low power CW or AM voice comms up and down the coast from remote campsites, or even while mobile. T-17 carbon microphone (of course) but powered by a homebrew 12 volt-HV power supply mounted under the seat. No room for a big DY-88 in here!
But I miss the sound of the dynamotor – The Song of Our People.

Available too late for WWII, the GRC-9 was widely used in Korea, throughout the 1950’s and early-on in Vietnam. For more information on the GRC-9, take a look here: AN/GRC-9

Bacon and cheese toasted sammitches

Oh, and good food; here breakfast with toasted cheese and bacon. Plus BLT (Battalion Landing Team) sammitches for lunch and all kinds of steaks, corn, ribs, potatoes, sausages and creek-chilled watermelons (and Survival Cylinders) for dinner. No avocado toast….

FOB Bigfoot: The trap is set

Here at Forward Operating Base BIGFOOT the trap is set at the Fuel Dump.

Did you hear that really loud THUMP at 0245 this morning? Woke everyone up….
Many strange noises in the mountains at night. Not just CW…

BTW, Bigfoot is a qualified Morse Code operator! Who Knew?

Sending his traffic from our RS-6 position.

Get out there and operate those old field sets! No Shelf Queens!

Shoot.  A fella’ could have a pretty good weekend in Vegas with all that stuff.”
Major T. J. “King” Kong