[ARC5] Re: [Milsurplus] Re: SCR-274-N Transmitter Dial Accuracy

[D C *Mac* Macdonald]

It's probably the same one I have.  9.56 Mb pdf file???
 
73 - Mac, K2GKK/5
Oklahoma City, OK
 
> Date: Tue, 8 Jul 2008 16:10:24 -0500> From: jhhaynes at earthlink.net> To: kk5f at earthlink.net> CC: arc5 at mailman.qth.net; milsurplus at mailman.qth.net> Subject: [ARC5] Re: [Milsurplus] Re: SCR-274-N Transmitter Dial Accuracy> > I have a portion of the maintenance manual for the B-25 C and D> airplanes, published by North American Aviation. It must be something> I found on the net, as I don't have a hard copy but a pdf. The B-25> was pretty small as bombers go, but it had a full radio complement.> SCR-274N, 3 receivers and 2 transmitters for command, BC-375 and BC-348> for liaison, radio compass receiver, IFF set, marker beacon receiver,> and a BC-221 frequency meter. The manual doesn't go into how all this> was used, so I don't know if the BC-221 was used only with the BC-375> or if it was also used with the SCR-274N transmitters in flight.> Those transmitters are in a rather hard-to-reach place, but then they> would be hard to reach on the ground as well as in the air.> > It says the command receivers are BC-453, 4, and 5. They are controlled> remotely from a 3-position box at the co-pilot's side of the airplane.> It says the transmitters are BC-458-A (5.3-7.0 mc) and BC-459-A> (7.0-9.1 mc) but that BC-457-A (4.0-5.3 mc) may be substituted for> either of these. That's curious since the standard tower frequency> was 4495 kc, but then maybe the people at NAA writing the manual didn't> know all about it either. Or maybe the standard tower frequency was> not all that standard.> > It lists various models of BC-348 receivers by various manufacturers,> as well as 1TA20D by Stromberg-Carlson. I had never heard of that one> before, but they don't say anything about it being any different from> the BC-348s.> > The picture shows six tuning units for the BC-375, in addition to the> one in the radio. There's also a trailing wire antenna.> > Jim W6JVE> > jhhaynes at earthlink dot net