CRD21 Comm Center:
Well, lets start here because this is one place the boats communicated with (and this site is about Combat Comms!). We built a shore Comm Center in the Great Lakes Naval Base boat house, headquarters for CRD21. Circa early 1973. Not many rules so we got creative ordering equipment through regular supply channels, visiting the base salvage area and generally “comshawing” anything we needed. It helped that the Navy’s Electronic Technician Class “A” School was at Great Lakes. The result was a pretty good setup that worked well.
As a tactical boat unit, we had no means to transmit or receive Record Traffic (hard-copy Naval Messages) aboard the boats. Since our shore base HQ was technically “temporary” (we could not take it with us) we had no record traffic capability there either. We were serviced by the Naval Training Center Comm Center who provided that service for us. We had the radio gear but a mechanical teletype machine would last about 10 seconds aboard a PTF!
We had two URC-32′s, 500 watt output, 2-30 MHz HF SSB transceivers, an R-1051 HF receiver, an SRC-20, 100 watt 225-400 MHz UHF transceiver, VRC-46/RT-524 running 35 watts, 30-75 MHz on VHF and a 25 watt Raytheon Ray-50 marine band FM radio.
Here’s a photo of LTJG “F” clowning with one of the URC-32′s. The SRC-20 UHF transceiver is behind him. The PRC-41 is on the floor to his left. Photo: Tim Sammons
Here’s a shot of the VRC-46, antenna and audio patch panels, the R-1051 and the PRC-25. The Ham-M antenna rotator controller is on top of the distribution amplifier. The chart on the wall assisted in pointing the Yagi antennas at the boats’ operating areas to optimize comms. The deep pattern nulls from the Yagi’s allowed us to get a decent LOP (Line of Position) out to the boats if The Skipper wanted to find us out on the Lake someplace – your basic radio direction finder…. Photo: Tim Sammons
We installed a 50 foot Rohn tower on the roof sporting a vertical Cush Craft 4 element 10 meter Yagi beam, which we cut and spaced for our primary tactical freq of 39.00 MC. Similarly, we had another vertical Cush Craft 220 yagi rebuilt for our 239.0 UHF AM freq and another 11 element Cush Craft Yagi rebuilt for 156.800 MC, Channel 16 marine band, with whips for the Ray 50 and HF transceivers.
The Yagi’s were rotated on a common mast by a Ham-M rotator, with all that equipment being bought from Amateur Electronic Supply in Milwaukee. They were surprised when we showed up in a Navy truck with a government purchase order to buy all this “Ham” stuff. I see on Google Earth satellite photo’s that the tower is still there 38 years later. Hope the Assault Craft Unit was able to put it to use!
The below photo shows the CRD 21 communications tower on the roof of Building 13, CRD21 Headquarters and the NTC Boathouse. At the top is the 39 MC, 4 element Yagi. Below that on a common crossarm is the 239 MC Yagi and the 156 MC Yagi’s. All 3 rotated by the Ham-M rotator. Below the rotator on a yardarm are the AS-390 UHF and 156 MC ground plane omni directional antennas. Photo: Tim Sammons
We also had an AS-1729/VRC whip for the VRC-46. We had an HF wire dipole cut for 6970 KC, our primary HF freq although the URC-32′s were pretty forgiving when used off freq on our other tactical channels. God bless Tube amplifiers and the URC-32 couplers! The Division Commodores, LCDR Jim Roper and LCDR Tim Johnston had a C-1138 Remote Control and handset in their second floor office so they could radio us rudder orders (which they never did – They were great officers, leaders and bosses).
The beams were handy because we did a lot of training in the Lake Michigan Controlled Firing Area, well out in the middle of the lake, out of range of the VRC-46′s / AS-1729 whip ground wave. The beams made the difference.
This Comm Center was designed to support our boats and ships during training work in the Great Lakes area and it performed well. A good combination of the Navy supply system, Navy SOP and Ham Radio pragmatism operating in a “don’t tell me how, just get it done” environment. The ET’s did a great job. More on that later.