BC-611's for a new radio addict?

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BC-611's for a new radio addict?

Postby dlk » Sat Apr 07, 2007 8:27 am

I have become addicted to fixing up tube radios as a consequence of working on my SCR506 and SCR508 systems. While these projects are unfinished at present (the 508 transmitter is fixed, the 506 transmitter is getting closer, the 508 receivers need help, and the 506 receiver appears to be "OK" but is untouched by me), these systems are too large for me to drag from the barn into the house to work on. (For that matter I am not sure how I will drag the nearly 200 pounds of the 506 into my M8. I also will not use them really..just the intellectual challenge of fixing them up.) I have therefore contemplated getting a pair of BC-611's to fix up and expand my radio horizons.

As I am a "radio rookie" I really know little about the BC-611's in terms of problems they have, parts availability, value, etc. I do have the TM (well...a copy of a TM).

Are they easy to work on?

Are parts available?

How much can they be purchased for?

What specialized test gear is needed?

What do you think?
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Postby willy » Sat Apr 07, 2007 9:25 am

Tubes and cristals are to be had.
But test equipment is very hard to find but every once a while people will sell off there equipment and if you are the one to buy go for it.
But the rewards are very limited on these type off radio's.
I have a FT51 I believe a adaptor the replace the A baterie with 2 D cells
and the B baterie you can make out off 10 - 9 volt batery's
Good luck
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Postby petesilfven » Sat Apr 07, 2007 3:09 pm

Don't ever assume that a 60 year old crystal will oscillate. It's kind of a crapshoot.
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BC-611

Postby Tom Chirhart » Sat Apr 07, 2007 4:10 pm

Well in order to use the BC-611 your best bet is to get a ham license and put them on 3885. I found a pair of BC-611 E's already on 3885. They were manufactured by Electrical Research Laboratories in 1944. I also have the SRC-543-D/BC-669 transmitter/receiver with power supply also made by ERL in 1944 so it's a nice match but I have to put the 669 on 3885 someday. The 611's can be pricey. I visited a military patch swap meet a year ago and missed a mint pair for $250 but that's a once in a lifetime deal. There are battery adaptor kits available using 9VDC and D cells, do a google search and you can find them. I have not bought the adapters and won't untill I get them all ready. (IF I ever find the time) The BX-49 has the TX/RX crystals for the 611's as well as the coil sets for but if you operate on 3885 and can get the TX/RX crystals and the coils :? then the BX-49 would only be for show n tell. 73 Tom K4NCG
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Postby wa5cab » Sat Apr 07, 2007 11:40 pm

(Wish I could figure out how to indent an excerpt and interleave the response. Doesn't appear possible on this board.)

BC-611's are a pain to work on compared to most larger sets (voice of long experience speaking). Some parts (tubes for example) are still pretty readily available. Others much less so. Typical going price for one radio in good condition is $150-$200. And that's my definition of good condition, not that of some yahoo who doesn't know a BC-611 from an MB.

In order to tune a BC-611 successfully, the chassis must be inside of a test case. If you tune it outside of the case (except for the receiver IF's), putting it into its case totally detunes it.

There were two test sets built for working on the BC-611, the IE-17-(*) and the IE-37. The IE-17-E is the preferred set, and consists of I-135-E, F or G Test Set, CS-81-(*) Test Case, FT-252 Test Stand and A-82-(*) Phantom Antenna. Plus a transit case and some minor components. The I-135 has a cable with a connector that plugs into the bottom of the radio chassis. And a multimeter that can be switched to measure the various voltages or functions, a microphone and earphone, an audio oscillator to modulate the transmitter, and a crystal test oscillator. The CS-81 has cutouts or holes over the coils or capacitors that must be adjusted. The FT-252 holds the CS-81. The A-82 you can get by without, as it is only used for a final check of modulation versus transmitter loading.

The IE-37 might be called the poor man's tuning set. It consists of a CH-312 test case (with cutouts for tuning) and a bottom cover similar to the one on the late BC-611-F, with a phone jack and a couple of pin jacks. With it, you use the internal batteries to power the radio under test, and another radio with a second special bottom cover (also part of IE-37) as both a detector for tuning the transmitter you are working on and a signal source for tuning the receiver. With the I-135, you use external batteries or power supply (I use a power supply).

You can make an ersatz test case out of a radio case and a late -F bottom cover (all original CS-81's were made from BC-611 case castings). But I wouldn't do it unless the case were damaged such as not to be usable on a radio. Instructions for drilling and slotting are in the 1945 TM 11-235. And use a standard signal generator for tuning the receiver and a field strength meter for tuning the transmitter.

FWIW, I-135-B is for the BC-721, but I have only ever seen two of them. I have never seen an I-135-A, C or D.

On the crystals, 3885 KC ones are becoming quite scarce. But if you ever come across a dud, don't throw it away as aside from corrosion or physical damage, they are 99-44/100% repairable. I have come across a lot of dead FT-243's. But I have never seen a bad crystal unless it had been physically cracked after being removed from the holder. There are in each FT-243 two brass contact plates with thin legs that go down into the pins where they are soldered to the pins. Every dud I've ever opened up had one or both legs broken off right where it leaves the plate. I've repaired many by salvaging plates with intact legs out of crystals made for sets no one is ever interested in. But the donor and the recipient pretty much have to have been made by the same contractor as they mostly all used different shape plates. Sorta like having to have the same blood type.
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Postby petesilfven » Sun Apr 08, 2007 8:22 am

Gunner, I just finished reading a brand new book titled: "Crystal Clear - The Struggle For Reliable Communications Technology in World War II." It's a really fascinating book on how crystal-controlled communications gear enabled us to have spot-on frequency control without the need for manual calibration by technicians. It made everybody a radioman.

More than that, it's almost a textbook on the handling and repair of WWII crystals, and the possibility of grinding one's own to change the frequency if needed. There are also charts of the various crystal series, and possible interchangeability.

Crystal Clear
Richard J. Thompson, Jr.
IEEE Press, Wiley Inter-science
ISBN 0-470-04606-6
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Postby dlk » Sun Apr 08, 2007 8:37 am

Crystal Clear
Richard J. Thompson, Jr.
IEEE Press, Wiley Inter-science
ISBN 0-470-04606-6[/quote]


I have heard about this book....it is available on Amazon....looks very interesting
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Postby petesilfven » Sun Apr 08, 2007 8:39 am

If you go on Amazon, look where it says "new and used from $XXX" and you'll find other retailers about 20 bucks cheaper.
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BC611's here in Australia

Postby Mike Kelly » Tue Apr 10, 2007 4:31 am

I and some friends have a had a few BC 611's in the past .

One particular model , E I think , has a common fault , the coils in the IF cans go open, and you have to spend hours pulling the can off the chassis to fix it . It's a very common fault with them .

I had trouble with filament batteries always going flat . They only lasted and hour and thats it . I made up the HT battery using ten 9V batteries , taped them up and it worked quite well . We had ours on 3530 , in the CW end of the band , I used to copy CW with the BC 611 .

They came onto the surplus market here in the late 1950's . I recall an old movie with Spencer Tracy and Katherine Hepburn , she plays a frustrated sporting star and on the golf course they use a BC 611 in one scene .

They are getting pricey here also , $200-300 each for a good BC 611 .

Mike VK3CZ
visit the Morris Commercial military website at: www.geocities.com/vk3cz
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Postby wa5cab » Tue Apr 10, 2007 3:47 pm

Mike,

It's the BC-611-F, which has the double slug-tuned IF transformers. And that is a common fault in ones I've had through here, as well. Some are repairable, some not. It depends upon how far from the coil pie the wire breaks.

The BC-611-E and earlier 1st IF works fine as a replacement for both of the ones in the -F. Unfortunately (Murphy's Law), the one that I have 100's of is the 2nd IF, which is not usable. One of these years, I may have to look into the practicality of build a good 1st IF out of two 2nds.

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BC-611

Postby willy » Tue Apr 10, 2007 4:06 pm

Robert,
I have 2 complete without the plug ins NOS chassis in box E type.
Any good valeu in that or should I keep because they matuere at higher rate like CD's do (money that is)
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Postby wa5cab » Tue Apr 10, 2007 4:39 pm

Willy,

My "retail" price for NOS BC-611-C or BC-611-E chassis (the only two models I have NOS) is $40.00 without coils, crystals, tubes, shields or antenna. In other words, less everything you can remove without a soldering iron or drill.

Whether they will be worth more or less in a decade I couldn't say. :-)
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Postby upandrunnin » Mon Apr 16, 2007 8:41 am

I dont mean to jack the thread but, If anyone here has a set of 611's that they are willing to part with, please let me know. I would even take a set that has been completly gutted for parts. I am mainly looking for the "look" of the radios for a display. Please let me know.
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BC 611

Postby willy » Mon Apr 16, 2007 8:52 am

upandrunning,
Do a search on BC 611 one member made some out wood may he made more it would fit your needs
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