What is a BC-645-A Receiver Transmitter?

[k4kyv]

I was curious about a <a href="http://cgi.ebay.com/HALLICRAFTERS-R-46-MODIFIED-TURNTABLE-SPEAKER_W0QQitemZ320030948476QQihZ011QQcategoryZ15 02
QQcmdZViewItem" target="_blank"><span style='color:Blue'>Hallicrafters speaker/turntable</span></a> on e-Pay. When I viewed the item, I noticed the following item listed at the bottom of the page under other stuff the seller has up for bid:

SIGNAL CORPS BC-645-A RECEIVER TRANSMITTER NEW IN BOX (starting bid) US $9.99

If the item doesn't appear at the bottom of the page, it may be accessed at <span style='color:Blue'>Seller's Store - 8d 07h 32m</span> (http://stores.ebay.com/RIATLA_W0QQcolZ2QQdirZQ2d1QQfsubZ0QQftidZ2QQpZ2QQt Zkm). Scroll down to the very bottom of that page.

But when I clicked on the <span style='color:Blue'>link</span> (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320033244483&ssPageName=MERC_VI_ReBay_Pr4_PcY_BID_Stores_IT&refitem=320030948476&itemcount=4&refwidgetloc=active_view_item&usedrule1=CategoryProximity&refwidgettype=cross_promot_widget), I got the following error message:

Quote[/b] ]Dear User:

Unfortunately, access to this particular category or item has been blocked due to legal restrictions in your home country. Based on our discussions with concerned government agencies and eBay community members, we have taken these steps to reduce the chance of inappropriate items being displayed. Regrettably, in some cases this policy may prevent users from accessing items that do not violate the law. At this time, we are working on less restrictive alternatives. Please accept our apologies for any inconvenience this may cause you, and we hope you may find other items of interest on eBay.

Any ideas about what could be &quot;illegal&quot; about this item in USA? Apparently it must be legal in other countries since e-Pay didn't pull the listing.

[KF0RT]

Must be something with your ISP?

It displays fine here...

73, Rob

[k4kyv]

Quote[/b] (KF0RT @ Sep. 30 2006,09:57)]It displays fine here...
Can you tell me exactly what the radio is?

[W0LPQ]

Some IDIOT, cut the top of an R-46 speaker to fit a turntable on it ... ruined that cabinet quickly...

Bill, W0LPQ

[k4kyv]

I'd bet the accoustical feedback between that turntable and speaker makes it a good audio oscillator.

As for the error message, I do have some non-USA language and keyboard settings on my computer. Maybe that makes e-Pay think I'm in some country that restricts access to military radios?

[KF0RT]

Quote[/b] (k4kyv @ Sep. 30 2006,11:14)]Quote[/b] (KF0RT @ Sep. 30 2006,09:57)]It displays fine here...
Can you tell me exactly what the radio is?
I really don't know much about WWII mil surplus gear, but that's what it is.

I wonder if I can direct link to the pics here...

Link 1 (http://www.nmia.com/~elecsurp/DT55.JPG)
Link 2 (http://www.nmia.com/~elecsurp/DT67.JPG)
Link 3 (http://www.nmia.com/~elecsurp/DT52.JPG)

Maybe someone here knows more specifics about what this actually is -- HF transceiver I'm pretty sure, but it appears to be missing the control head. Built in 1942.

73, Rob

[W0LPQ]

Rob, finding a control head would be ... interesting. Not to mention the cost of mating connectors on this thing. If it is HF, then it is AM and not all that much power either.

Relic that should be sent to the CAF for one of their fleet they keep rebuilding..!

Bill, W0LPQ

[KF0RT]

Quote[/b] (W0LPQ @ Sep. 30 2006,11:46)]Rob, finding a control head would be ... interesting. Not to mention the cost of mating connectors on this thing. If it is HF, then it is AM and not all that much power either.

Relic that should be sent to the CAF for one of their fleet they keep rebuilding..!

Bill, W0LPQ
There appears to be a fair amount of info on the net about this thing, Bill. An IFF transponder maybe, whatever that is. Could be that there are no controls.

Apparently, it's UHF.

Another link. (http://www.qsl.net/kp4md/bc645.htm)

73, Rob

[N7CPC]

IFF means &quot;Identification Friend or Foe&quot; and I don't think they had them in WWII. Level of radar sophistication not being up to it.

[W0LPQ]

Craig I think toward the end of the war they did. This is the military version of a transponder that commercial/corporate/private aircraft use. It uses a different frequency, since the 1 gig range had not really been investigated as of then.

Relatively low power. ATV use is interesting however. Radar as such does not interrogate the system, it is the narrow antenna on top of the radar dish that does the work. Now the systems use 1090/1030 Mhz.

Yes it does require a control head to input the code numbers that are/were used and select the mode desired.

Bill, W0LPQ

[n0jaa]

I found a little information on this item and a companion dynamotor...

BC-645-A Transceiver and PE-101-C Dynamotor (http://www.nf6x.net/greenradio/pe-101-c/pe-101-c.html)

[ka5piu]

Hello.

The &quot;old&quot; IFF system runs at 200 to 225 MHz, same as the 220 band.
IFF predates RADAR by quite a few years, at least in the modern sense.
The very early RADAR ran at HF.
http://www.centennialofflight.gov/essay....h39.htm (http://www.centennialofflight.gov/essay/Evolution_of_Technology/radar/Tech39.htm)
The early IFF system worked by pinging the transponder with a coded poll.
The unit would respond only to the correct code and reply with 2 framing marks at tight timing.
By measuring the timing marks and reply the aircraft could tell how far the other unit was.
The later system, as pointed out, operates in the 1030 MHz
and 1090 MHz bands, the ground RADAR normally has the transponder antenna on top of the main antenna.
There were several assn' of old crows who took the time to teach me this ages ago.
The IFF system and the military aero band, 200 to 400 MHz is still in use in most of the worlds military.
This is mode X, also supported in the 30 to 76 MHz band.
The Vietnam era UH1b would normally have the ADF unit and and antennas mounted on the nose of the aircraft.
There is a KY something or other crypto device that would support crypto and IFF.
The guard channel in that era was 40.5 MHz for ground.
The good thing is that this works well for ground troops.
Prior to this was the AN-PRC 8,9,and 10 series of pulse generator encoding for ground IFF.
The current distress beacons run at 243.0 MHz if &quot;open&quot;.
If closed, mode X with GPS support.

[W0LPQ]

The APX-72/APX-100 transponders (aka IFF) were used starting the mid 60's, with the -72 starting first, then tne -100 coming along in the mid 70's. #Both are 1030/1090 Mhz and have a mode control switch labled 1/2/3/4/C.

Modes 1-4 are strictly military, Mode C is the typical transponder that encodes altitude with what was called Gray or Gillham code. #Ground based units (airports etc) could read out their altitude as being reported by an Air Data Computer or Encoding Altimeter.

We had to interface with these units on 2 programs that I was involved with at Collins. #

The UH-1 had a Collins 37R-2U UHF/VHF blade on the nose. #Typically the ADF antenna was mounted underneath the sctructure. #There was also a DF-301E which was a UHF ADF system. #That had to be flat mounted underneath also, since there was no actual room on top and due to rotor modulation, which made things pretty useless on top.

The HF was usually a wire coming out the bottom running along either the side or bottom of the tail boom.

There is a web site with further info.

http://www.fernblatt.net/index.html

Edit to add:

PRC-8 -- Radio set, 20-28mHz, FM, 1w
PRC-9 -- Radio set, 27-39mHz, FM
PRC-10 -- Radio set, 38-55mHz, FM

[ka5piu]

Hello.

The radio in the UH1b I am looking at has &quot;ARC-131&quot; listed in the aircraft manual.
In the avionics bay is &quot;Receiver-Transmitter, Radio&quot;
&quot;P/O Model FM-622 A&quot;
This is in an aircraft that was marked &quot;Air America&quot; at one time.
I trained on one just like it, marked &quot;Southern Air Transport&quot;
We did NOT use the UHF aero band, none of the aircraft were equipped with UHF.
To home in on the VHF beacon, the radio would be set to home, watch the needle, it would point the way.
ALL of the aircraft had and have HF and VHF aero, 108 to 149.975, AM or FM.
SOME aircraft had and have 30 to 76 or 88 MHz FM carrier or 150 Hz tone.
The exception is the CH 47, that thing has coverage from 1 MHz to at least 512 MHz with no gaps.
We are not part of the military, so the aircraft have no visible weapons.
But, where else can you fly in high heel cowboy boots one day and Arabic sandals the next?
NO dress code, if it fits in your footlocker, you can bring it back.

[k4kyv]

I accessed the e-pay site on the same computer using my wife's Windows XP profile, and the item came up normally. But under my own profile I still get the error message, both with IE and Firefox.

Evidently there are certain countries where such a radio would be illegal to sell, and e-Pay thinks I am located in one of those countries, but not my wife.

Strange.

[W0LPQ]

Collins with an avionics dealer, installed TCAS-II (Collision Avioidance) on the Southern Air C-130's on site at Rickenbacker. Shortly after, the outfit ceased to exist. We got our money for the equipment, but think the avionics dealer got stuck for some. I was directly involved with that fiasco.

The ARC-131 was made by Magnavox. Radio set, 30-76mHz, 920 chan, FM, 1 or 10w, 28 VDC at 4 amps.

Early UHF radios were replaced by the ARC-159 (Collins) or ARC-164 (Magnavox).

[ka0gkt]

IIRC, the BC645A is an IFF (Identify Friend-Foe) transmitter. #There was an article back in the late '50s or early '60s in CQ 73 or Ham Radio magazine (I don't remember which) to convert that unit for use as a 70 cm Fast Scan ATV transmitter.

Indeed, IFF was in use during the second world war; the first active system used by the allies employed radio energy generated onto the target aircraft and then used for the return signal. This is the basic method now used in all modern cooperative IFF systems.

Around 1940 an active system, designated the Mk I, was put into service. It used a receiver aboard each aircraft that broke into oscillation and acted as a transmitter when it received a radar signal. Because of the variety of radar frequencies used, it had to be mechanically tuned across the radar bands in order to be triggered by any radar that was illuminating it. This mechanical tuning requirement and other factors limited its performance. The system was developed further by the addition of a separate transmitter that was tuned through the radar bands simultaneously with the receiver and was triggered by signals from the receiver. This greatly increased the strength of the return signal and the return range. Known as Mk III, it also could be programmed to respond in one of six different codes thus providing some further degree of identification.



73 DE KAØGKT/7

--Steve

[ka5piu]

Hello.

I was in a &quot;sanitized&quot; section of Southern Air.
We would fly out of a major cities &quot;normal&quot; airport, land at a military base for the 'hop' and go to the final.
For me, that would mean San Antonio International, on to Kelly AFB, and onward.
We had removable N numbers that look perfect once on.
The CH-47 aircraft look a lot like civil aircraft, the avionics was just a touch off, but nothing totally out of place.
What is now declassified is the really neat water based paint.
http://www.magiccolors.net/
We got a head start with Mary Carter paints.
The stuff we had was a lot like tempra paint, but an oil emulsion, the oil would rise to the surface and act as a protective layer and give it the sheen.
High pressure like in a car wash would break the bond.
The paint came with a cardboard color wheel, to help select
the paint mix for whatever color you wanted.
15 cans and you could come up with any color.
Our portable radios were at first things like the HT-220 but the current crop are hacked ham talkies and GSM cell phones, nothing looks out of place to the average joe.