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MIFlyer

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  • Location
    Merritt Island, FL, USA
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    WWII Aircraft<br /><br />Military radios of any era, but especially WWII<br /><br />Armored combat vehicles
  1. If you go over to Archive.org and do a search for TRC-7 you can download a manual for it.
  2. You can buy them at FairRadio.com and also may find them on ebay. Ebay has had some very good prices on the bags I built a rechargable battery pack to fit my two PRC-77's and my PRC-25.
  3. That PL-54 on those headphones is 1/4 inch in diameter but is too short to fit a standard 1/4 jack. You can buy a CD-307 adapter cord from FairRadio.com that will adapt the headphones to a standard 1/4 inch or just buy a JK-26 jack and make your own.
  4. That model of receiver generally was used as an Intermediate Frequency receiver for a UHF converter that was part of a navigation system. The carriers and bases transmitted a signal in the 230 MHZ range and the converter's output was fed into that radio A Morse code signal, for example "A," was sent when the transmitter antenna rotated past due North. 5 degrees later a "B" was sent, and so forth. The pilot received the signal and if it was "A" he knew he was due north of his destination. :
  5. Nice set! But that is not a BC-348-O. That is a BC-348-Q.
  6. I have what I believe is an original BC-620-F. The name tag on it has a plastic cover that was freshened up considerably with an application of Marvel Mystery Oil. I have acquired an original manual and all the required tubes as well. Acquisition of the set was a rare delight. I found it sitting by the road a quarter mile from my house with a sign that said "Free. Take it!"
  7. Cinncinatti Electronics was the original manufacturer. Associated industries would have been the overhaul contractor. I believe that company also took older radios such as the PRC-6 and upgraded them from tubes to solid state. The green color paint used seems to be the same color used by the US Army Depot at Tobyanna during overhauls; I have a couple of PRC-77 cases that came from there in newly overhauled condition. Take a look at Radionerds.com. I have an article there on how to build an adapter to use the nearly identical earlier PRC-10 antennas, which are more easily available and much cheaper than the PRC-77 antennas are now. I built rechargeable Li-Ion battery packs for my PRC-77's and PRC-25. They use the H-250 handset which you can find on ebay for maybe $15-$20. Good luck!
  8. I have a BC-620. As compared to the BC-659 and the BC-1000, the BC-620 operated on Armor frequencies. Thus, presumably the BC-620 was used by troops scouting for armor units. The BC-620 was tried out as an answer for communicating with tanks during the fighting in the hedgerow (Bocage) country in Normandy. A backpack version was created, and you can imagine what it must have been like walking around with the equivalent of a full sized microwave oven on your back! The interim answer was to put field telephone boxes on the rear of the tanks, hooked into the intercom, so that the troops could tell the tanks thing like, "Shoot over there to the right. There is a machine gun position we need to take out." I don' think the problem was solved until the RT-70/GRC short range set was installed in tanks after Korea, able to talk to local infantry units with their PRC-10's and PRC-6's There is a picture in the Warren Thompson book on P-51's in Korea of some ROK troops with a BC-620 on high ground above a major armor engagement, presumably scouting for the tanks.
  9. I wonder how much of the failure to develop true FAC capabilities was due to attitude and careerism and how much to technology. I have an SCR-522 - it's a BIG set, and using one in the field would be like carrying around two of today's microwave ovens along with a 1960's TV set. There were huge advantages to using VHF for aircraft comm, but other than strapping an SCR-522 to a jeep there was no way for forward ground units to use it. And of course ground units already had HF sets in use. But the other thing was that airpower theories focused on an independent air force fighting its own battle rather than being an "Army Corps" supporting the infantry in the same way that the Signal Corps and the Tanks Corps did. Before WWII some in the Air Corps feared that lightweight communications technology would allow a Private on the ground in a forward area to take control of a air force bombing mission and divert it from the targets selected by the air staffs. Of course for some CAS missions the only thing that made sense was for a FAC in the battle area to tell where they needed the bombs. This even continues today. Using USAF, Army, USN, USMC to tell the B-52's where to drop their bombs in Afghanistan was decried as wresting authority from the staffs in the Air Force units. By the way, I have only read of a few cases of BC-611's being used to talk to airplanes and they were all rescue operations in Burma. In those cases the C-47's would drop supplies and rescue personnel and then be able to discuss the situation using the handi-talkies. Mostly the BC-611 was too short ranged to be able to hail an airplane unless it was right overhead and looking for someone.
  10. The antennas that fit the PRC-25 and PRC-77 seem to have gotten scarce and expensive. But the nearly identical AT-272A antenna for the PRC-8-9-10 are still available at pretty reasonable prices. I decided to make an adapter to enbale teh AT-272A to be used on teh PRC-25 and 77. I found I could buy 1 inch long pieces of 0.75 in diameter brass rod on ebay, three for $8.30, including shipping. This is exactly the size of rod needed for the adapter. Take one of the pieces of brass rod and drill a small hole, about 1/8 inch diameter or so, through it lengthwise. Then you need to enlarge the hole in one end to enable you to tap it for ¼-28 thread, such as with a 7/16 drill bit, about a half inch deep. The other end of the adapter you need to drill out to enable you to tap it with a 5/16-24 thread. The proper diameter of the hole is 0.2703, but a 9/32 drill bit should work Okay. Don’t drill deeper than about a half inch. Then take a 5/16-24 bolt and cut the head off, or else buy a 5/16-24 stud, and insert it in the threaded hole. You do not want it sticking out of the brass adapter more than a half inch or else it won’t screw all the way into the radio. Now you have an adapter that can enable the AT-272A to be used on the PRC-25 and 77 instead of the AT-892. It is almost identical and seems to work just as well. Good luck!
  11. I used to have one of those. I was not too impressed with it. It uses some relatively hard to get tubes.
  12. An interesting aspect of FAC activities is what occurred in Burma. The earliest close cooperation between air and ground units occurred there, since use of aircraft for both supply and close support was intrinsic to operating behind enemy lines. The USAAF Air Commandos were equipped with P-51A's still fitted with HF SCR-274-N radios. The RAF units had gone over to the SCR-522 VHF set - and thus could not talk to the ground units - and they asserted they had no need to, since they could properly brief their pilots before takeoff. But the P-51A's still had the SCR-274-N, could talk to the ground units, and the Air Commandos considered that using ground observers to call in air strikes to be a great idea. The result was that backwater war in Burma was way ahead of the rest of the Allies.
  13. I have one of those, as well as a few of the Detrola set that was similar in terms of use but a bit different in design. I do not believe that the terminal strip on the back is original. The original had the phone jack on the front, the antenna jack on the left side and a wire coming out of the back. That's all. The case would short out that terminal strip if installed. Here is little write up i did on those sets: The Cutest Aircraft Radios They Ever Made: The Detrola Model 438 and the BC-1206 In the 1940’s the standard aircraft radio navaid system in the U.S. was the AN Range. The AN Range predated the widespread use of Automatic Direction Finding receivers and used the 200-400 KHZ aircraft navigation band. Use of the system only required an ordinary AM receiver tuned to the band. Pilots would tune in the station that best corresponded with their destination, listen to the signal, and hear either the Morse code signal “A” which indicated they were to the left of the desired course, the Morse code signal “N” that indicated they were to the right of the desired course, or a continuous tone, which indicated they were right on course. Everyone with an aircraft sophisticated enough to have a radio used the AN Range, and so many light aircraft were equipped with only receivers for the 200-400 frequency that most control towers were set up to transmit on 278 KHZ for the purpose of giving landing and takeoff clearances to aircraft. For this reason, when the USAAF adopted the SCR-274N “Command Set” receivers and transmitters early in WWII, a standard equipment set consisted of a BC-453 receiver for 190-550 KHZ, a BC-454 receiver covering 3-6 MHZ and a BC-455 for 6-9.1 MHZ, together with a couple of transmitters, enabling coverage of both the AN Range as well as the standard control tower frequencies and other required military communications. When the USAAF got to Europe, it found that the RAF had adopted VHF for fighter aircraft communications, using a crystal controlled set known as the TR1143. The Americans had to be compatible with the British when it came to fighters, and VHF gave far superior short range communications anyway, so the U.S. built the British set as the SCR-522, and adopted it as the standard radio for fighters, at least in Europe. VHF was a big advancement but it caused a bit of a dilemma, especially for fighters operating in the U.S., which had to still use the AN Range for navigation. Overseas, low frequency beacons were less available and a lost fighter pilot would call for DF steer from a ground station. But fighters flown in the U.S., at least, had to have the low frequency receiving capability. Problem was, the SCR-522, while no more bulky than the SCR-274N receivers, transmitters, and modulator, still took up virtually all of the available room in the aircraft. Also, the fighters deployed to Europe would not necessarily require the low frequency capability, so an easy add-on capability was desirable to keep things as standard as possible. The answer to this problem were the two cutest aircraft radios ever built; the Detrola Model 438 and the BC-1206. Both the Detrola and the BC-1206 were designed to operate directly from 24VDC, without a dynamotor, and to be set up so that they could fit into a standard aircraft 3 inch instrument panel hole. They were small enough to be mounted directly in the cockpit with no more than a power lead and an antenna connection. Using their headphone jack, the sets could be plugged directly into the same audio circuit used by the SCR-522, so switching between radios was not required. They could be installed or removed within minutes without affecting the VHF installation. The Detrola went into the later model P-38, P-51, P-47, and some P-63’s, fitting right into the cockpit, possible because the remarkably small receivers were only about twice the size of the control boxes used for the larger radios. The P-51 and P-47 had the little set right next to the pilot’s seat, facing upward at an angle, while on the P-38 it was to the right of the pilot’s seat, almost resting on the floor, facing up. On the P-61 it was in a rather strange installation behind pilot’s right shoulder, the dial facing forward. The P-63 manual I have describes the Detrola as a “portable” installation, even though it is bolted down under the main radio panel at the bottom of the instrument panel and the P-38 manual says the Detrola “may still be installed.” Presumably this indicates the possibility that the set was yanked out when the aircraft was deployed overseas. Interestingly enough, none of these installations used the set’s ability to be installed in an instrument panel hole. All installations used long wire antennas; on the P-51D, the Detrola antenna is the long wire coming through the hole in the top of the bubble canopy and stringing back to the tail. In contrast to the Detrola use and installations, the only manual I have found that mentions the BC-1206 shows it installed in a side instrument panel hole in a P-80A, the early model Shooting Star jet fighter. The two sets fulfilled an identical function and were clearly made to identical specs, but are actually quite different electronically. I have always assumed the Detrola and BC-1206 were just related models of the same radio but recently found out they are very different. The Detrola Model 438 was made by the Detrola Company, and employs five standard WWII type octal tubes, including a VT150 oscillator/mixer and a couple of 6L6’s for audio output. The BC-1206 was built by Setchell Carlson and uses five 14 volt loctal tubes like the 14A7 and 14J7 and a 28D7 output tube. Both have an unusual antenna spring loaded lead socket on the left lower side near the front, use a combined volume/on/off switch, and have a ¼ inch headphone jack on the front. While the tuning knob on the Detrola simply operates a geared pointer against a frequency dial painted on the face of the set, the BC-1206 has a window over a dial to show the selected frequency. While the Detrola was used extensively in the U.S., I don’t know if it actually went to combat. However, the period photos of P-51’s in Europe show the long wire antenna, even though an SCR-522 usually can be seen behind the pilot, so one would presume those wire antennas were hooked to something Postwar, the Detrola and BC-1206 were replaced in refitted WWII aircraft and the newer jets by the BC-453 and/or the new ADFs such as the ARN-6 and ARN-7. No doubt the larger sets were much better receivers, - but they were not half as cute!
  14. You can download a copy of the SCR-536 BC-611 handi talkie Technical Manual, TM 11-235 at: http://bama.edebris.com/manuals/military/bc611/ Good luck!
  15. The latest FAQ on the CMP website says that they will NOT be selling the 1911's
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