MILITARY COLLECTOR GROUP POST, May 21/98 INDEX: PRC-74 SELECTABLE SIDEBAND; Jim Karlows Contribution MEMBERS WRITE; WW-II Forest Service Radios, PRC-25 Troubles, Saturday/Manuals Day(MCGP Paper Trail), REVISED MUSEUM DOWN SIZING LIST; HUMOR; *********************************************** PRC-74 SELECTABLE SIDEBAND; Jim Karlows Contribution After a struggle with suppliers for the parts for the conversion, I finally have a robust enough conversion to add LSB to the PRC-74 without allot of tweeking and fine tuning. I think now I can offer this to members of the group and be confident that, after installation, the conversion will provide a high level of satisfaction. The cost to group members is $ 35.00 plus $ 3.00 for shipping. Included are parts for the conversion, as well as a detailed instruction sheet to make the conversion. Total time to complete the job should be about 2 hours. The way the conversion works is as follows: The PRC-74 uses a 1750 KHz IF frequency. In the USB mode, a 1750 KHZ injection frequency is used to feed the product detector on receive, and to develop the USB IF signal through the 1750 KHz IF Filter. Because 1750 KHz Filters are nearly impossible to get, in the LSB mode, this conversion shifts the injection frequency to 1747 KHz. This is done by adding a small 1747 KHz crystal controlled DIP oscillator in available space in the frequency standard module. In the LSB mode, power is removed from the 1750 KHz standard and the DIP oscillator is turned on, providing the LSB injection frequency. In order to maintain correct dial calibrations when the mode is switched to LSB a small trimmer capacitor and reed relay are added in the synthesizer. In the LSB mode the relay is energized, switching in the trimmer cap which moves the synthesizer down 3 KHz, compensating the frequency synthesizer to maintain dial calibration in the LSB mode. The only cosmetic changes to the radio for the basic conversion is the removal of the two binding posts on the front of the radio. The "ANT" binding post is replaced with a BNC connector. The "GND" post is replaced with the LSB/USB switch. This is not a business for me,only a hobby. It is something I can share with other group members that will make the PRC-74 more fun to use. The price I charge just covers the costs for the parts, including the custom made DIP oscillators and reproduction costs for the instructions. I have about 5 kits left, with my current parts inventory. If more people are interested than I have kits, I will place an order for more parts. The DIP oscillators are the long lead item, with about 4-6 weeks required for delivery. Jim Karlow ed) While similar conversions of the PRC-74, and PRC-47 have been known of for some time, many(in the case of the PRC-47) and all( for the PRC-74) suffered from one major drawback. This was the shift of the displayed frequency on the radios dial when used in LSB, a real pain in the ass. Jim has succeeded in overcoming this common failing. He also has a completed design for the PRC-70, though it is possible that this one need be installed by him do to it's technical nature, but I don't know this for sure. Rumor has it,a similar design in the works for the GRC-106, I can't wait to see! *********************************************** MEMBERS WRITE; WW-II Forest Service Radios, What is the nomenclature of your set. I just picked up a book on radios in the Forestry Service and might be able to help. Joe Pinner ed) I've been told of a book that detailed at least one of the Forest Service radios, and was promised the loan of it several years ago, but it never happened. The particular radio in my collection is the Forest Service Type SPF built by Spokane Radio Company, Spokane Washington, is marked U.S. Army Signal Corps, and has a Phila 43 order date. It's a small thing capable of operating both AM and CW, and is housed in a gray wood box. Other than that, I don't even know it's frequency range. The only references to it I've ever seen were in two old WW-II vintage magazines. One was in the September 1944 issue of Radio News where it is pictured in use by a Forest Service licensed operator, the title of the article was "Radio Theory Review for FCC Operator Exams", I might add that this same issue also contains one of the very few pictures existing of an MAB in service. The second was an RCA tube add that contained a picture of it with a battle seen in the background complete with bombs exploding, and parachutist, though it is very doubtful this radio was ever used in such an environment. Two possibilities exist for the reasoning behind it's Signal Corps markings. First is the fact that all manufacturing, and especially that of electronic equipment, was very tightly controlled during WW-II, and all products had to be approved through Philadelphia or other official depot. The second is in the fact that Forest Service responsibilities were taken over by the Army during WW-II, partially because of the Japanese balloon bombs which were kept highly classified so as to minimize their intended psychological effects. Several historic documents also mention a Forest Service radio that was forced into service by the OSS in it's early days for lack of a more suitable, or available radio. While I do not believe that this was an SPF, it would be very nice to know exactly which one it was, especially as there has been much debate over the subject. ----------------------------------------------------------------------------------- PRC-25 Troubles, Hi Dennis, Can you or anyone on the list recommend someone to repair my PRC-25. It's been out twice, repaired(?) and returned to me. The repair facility I've had the unit to is very well known, cooperative, friendly, and willing to try again. Seems the radio works for them after their repair but by the time UPS has played with it and I do a field check its again non-operational. . (It still will not transmit and in all probability it's the A20 or A11 module.) Anyone have any ideas or should I just retire the set to the display/paperweight pile. Thanks to all in advance. Hal ed) Hal, the PRC-25 is a relatively simple radio to work on, especially if you have some replacement modules. If all the suspect modules have been replaced, and your trouble persist, the problem is most likely on it's main chassis. Intermitents in this area are often hard to find because the MFP treatment applied to these radios is unusually thick. This to the point that some interconnecting wires are submerged in it. Persons not familiar military radio equipment, MFP, or servicing equipment that has been treated with it often make the mistake of thinking they can burn threw it with their soldering iron to effect repairs. You can't! The stuff must be cleaned off first. Solder will flow on this stuff almost as nicely as it does on the desired connection creating the elusion of a satisfactory joint. This is common to all radios that have been MFP'd. I suggest that if all the associated modules have been replaced, yet the same condition persist, then get yourself some Freeze Spray from your preferred source. Spray each suspect connection then wait to see if condition changes either for better or worse, once it does, you've found your problem. If after you've tried this but still no luck, then spray a small area of the mother board itself. Hairline cracks in the copper trace are a common fault, and again the MFP will make isolating them more difficult. Wiggling, bending, banging, and heat are also useful methods of finding intermittent failures, but not usually as effective as the freeze spray. Use the stuff sparingly as it's getting expensive as hell, at it will use up FAST. If all the above fails, and you do not have replacement modules, you can often remove the modules shield, place it back in the radio, and repeat the above on the suspect module itself. This will not be very easy in some cases. Dennis ---------------------------------------------------------------------------------- Saturday/Manuals Day(MCGP Paper Trail), Dennis, if you can, please try out the manuals day. I have read your news letter, trying to get in the flow without making a bunch of useless comments but the manuals thing is perfect. Breck Smith ed)NEVER be afraid of sending me "useless comments", I can use nearly anything sent me. If not, the delete key is close at finger! Whatever you call it - I like the idea. I am always searching for a manual for something that I have. 73 Joseph W Pinner HI DENNIS THE SATURDAY MANUAL DAY SOUNDS REAL GOOD TO ME. I DON'T HAVE A LOT OF MANUALS, BUT WHAT I DO HAVE I WOULDN'T MIND MAKING COPIES OF THEM FOR COST PLUS POSTAGE. I WOULD HAVE TO GO TO ONE OF THE LOCAL COPY PLACES TO HAVE THEM DONE. AS FOR THE TITLE I LIKE "THE THINGS HILLARY DIDN'T SHRED." TODD H. ed) OK were gonna du it. I'll come up with a format in the next couple days, in the mean time you can all start working on your entries. I think we'll go with Lenox's first title of "Paper Trail" with my addition of MCGP on the front for "MCGP Paper Trail" how's that? Sorry Hillary.........NOT! One thing I do know in regard to the format, your line should start with the item of interest, followed by the title line, then TM or applicable number, and end with the publication date. This will make searching the list much easiar. Examples: AT-150/SRC, Antenna, Instr Book, Navships 91338, Jun.50(copy) B-17 Flying Fortress, by H.P.Willmott, HB, Bison Books Lmtd.1980 Military Communications,1st ed.HB,Jane's,1979-80(HB denotes hard back) GRC-106, Radio Set GRC-106,di sup & gen sup maint man.TM11-5820-520-34,Feb.72 In the case of manuals wanted, and an original only is acceptable, the line should end with (OO), nothing is needed if a copy is ok. If a manual offered is a copy, the line should end with (copy). While it would be nice to be able to put these in alphabetical order, I don't kow if this would be feasible or not. We'll see if there is enough input received to begin posting on this comming Saturday. Once this post is began, ALL entries for printed material in the Sunday Group Want's/Trade's will be deleted. Regardless of whether or not your input has been received for the Paper Trail. So get busy. Dennis *********************************************** REVISED MUSEUM DOWN SIZING LIST; The Louisiana Museum of Military History, due to financial realities will be will be moving to smaller quarters. We have been asked to help liquidate some of the Commo gear. Below is the first list of equipment that's been made available. If you have an interest in any item contact Joe below via email and he'll pass along any needed info. AM-1780 untested but good condition $ 25 AM-2060 with cable $ 95 AS-2851 30-80 log periodic complete $ 125 BB-451 NOS with electrolyte kit $ 185 BB-451 used $ 100 BC-639 untested but good condition $ 35 CPRC-26 with most accessories $ 70 CU-2267/GR Five unit multicoupler - with two spare F-1482 $ 125 CY-6121/PRC-74 Wet cell battery box $ 25 DY-105 untested but looks good $ 45 DY-105 no dynamotor $ 25 GRA-71 almost complete $ 125 GRC / VRC lots of cables ASK GRC-109 details later GRR-5 ASK MD-522 with cables $ 100 PPS-4 complete except for optical sight $ 300 PRC-25 with accessories $ 300 PRC-41 with antenna / PP-3700 AC supply - working $ 175 PRC-68 with handset, antenna and battery - working but a little rough $200 PRC-68 with handset, antenna and battery - working, good condition $ 235 PRC-77 with accessories $ 350 PRC-90 with battery - working $ 100 PRC-90 with battery - no 282.8 transmit $ 50 PRR-9/PRT-4A working w/manual copy $ 50 R-392 good condition with power cable $ 200 R-442 working, good condition $ 225 RT-524A unchecked $ 300 RT-524A working $ 500 RT-68 no meter $ 40 RT-858/PPS-6 RT only Make offer Russian 62R1 VHF cargo pocket transceiver with mike and dipole wire antenna - ASK Make offer Russian R-105M no accessories $ 100 Russian R-108 no accessories $ 100 TRC-77 untested but good condition $ 75 TS-323 good condition $ 35 TT-722/TG untested $ 50 ITEMS NOT FOR EXPORT All reasonable offers will be considered All items plus shipping Payment to: Glen Thibodeaux c/o Louisiana Museum of Military History P. O. Box 92110 Lafayette, LA 70509 If folks would just contact me directly, I will take care of getting things to Glen. Joseph W Pinner EMail: kc5ijd@sprintmail.com *********************************************** HUMOR; Subject: Air Traffic Control Humor The controller working a busy pattern told the 727 on downwind to make a 360 (do a complete circle, usually done to provide spacing between aircraft). The pilot of the 727 complained, "Do you know it costs us two thousand dollars to make a 360 in this airplane?" Without missing a beat the controller replied, "Roger, give me four thousand dollars worth." ------------------------------------------------ November 15, 1996 - What the...?! PSA was following United, taxiing out for departure. PSA called the tower and said "Tower, this is United 586. We've got a little problem; go ahead and let PSA go first." The tower promptly cleared PSA for takeoff before United had a chance to object to the impersonation. ------------------------------------------------ November 8, 1996 - Which Exit Did You Say That Was? A DC-10 had an exceedingly long landing roll out after landing with his approach speed just a little too high... San Jose Tower: "American 751 Heavy, turn right at the end if able. If not able, take the Guadalupe exit off of Highway 101 back to the airport." ------------------------------------------------ September 6, 1996 - Mmmm-mmm, Good! Tower: "Eastern 702, cleared for takeoff, contact Departure on 124.7." Eastern 702: "Tower, Eastern 702 switching to Departure... by the way, as we lifted off, we saw some kind of dead animal on the far end of the runway." Tower: "Continental 635, cleared for takeoff, contact Departure on 124.7... did you copy the report from Eastern?" Continental 635: "Continental 635, cleared for takeoff... and yes, we copied Eastern and we've already notified our caterers." ------------------------------------------------ June 28, 1996 - No, That's not what I Said! O'Hare Approach Control: "United 329, traffic is a Fokker, one o'clock, 3 miles, eastbound." United 329: "Approach, I've always wanted to say this... I've got that Fokker in sight." ---------------------------------------------------------------------------------- Jack goes to the doctor and says "Doc I'm having trouble getting my penis erect, can you help me?" After a complete examination the doctor tells Jack, "Well, the problem with you is that the muscles around the base of your penis are damaged. There's really nothing I can do for you except if you're willing to try an experimental treatment." Jack asks sadly, "What is this treatment?" "Well," the doctor explains, "what we would do is take the muscles from the trunk of a baby elephant and implant them in your penis." Jack thinks about it silently then says, "Well the thought of going through life without ever having sex again is too much, let's go for it." A few weeks after the operation, Jack was given the green light to use his improved equipment.He planned a romantic evening for his girlfriend and took her to one of the nicest restaurants in the city. In the middle of dinner he felt a stirring between his legs that continued to the point of being painful.To release the pressure Jack unzipped his fly.His penis immediately sprung from his pants,went to the top of the table, grabbed a roll and then returned to his pants. His girl friend was stunned at first, but then said with a sly smile, "That was incredible!Can you do it again?"Jack replied with his eyes watering, "Well, I guess so, but I don't think I can fit another roll in my ass." ---------------------------------------------------------------------------------- Three contractors were touring the White House on the same day. One was from New York, another from Missouri, and the third from Florida. At the end of the tour, the guard asked them what they did for a living. When they each replied that they were contractors the guard said "Hey, we need one of the rear fences redone. Why don't you guys look at it and give me a bid. "So to the back fence they went. First up was the Florida contractor. He took out his tape measure and pencil, did some measuring and said, "Well I figure the job will run about $900. $400 for materials, $400 for my crew, and $100 profit for me." Next was the Missouri contractor. He also took out his tape measure and pencil did some quick figuring and said, "Looks like I can do this job for $700. $300 for materials, $300 for my crew, and $100 profit for me. " Then the guard asks the New York contractor how much. Without so much as moving the contractor says, "$2700." The guard, incredulously looks at him and says "You didn't even measure like the other guys! How did you come up with such a high figure?" "Easy" says the contractor from New York, "$1,000 for me, $1,000 for you and we hire the guy from Missouri." *********************************************** (The preceding was a product of the"Military Collector Group Post", an international email magazine dedicated to the preservation of history and the equipment that made it. Unlimited circulation of this material is authorized so long as the proper credits to the original authors, and publisher are included. For more information conserning this group contact Dennis Starks at, military-radio-guy@juno.com) *********************************************** --------- End forwarded message ---------- --------- End forwarded message ----------