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 Post subject: BC-342-N
PostPosted: Nov Sun 05, 2017 11:26 pm 
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Location: Costa Mesa, California
I hoisted the BC-342-N up onto the workbench this weekend and gave it a quick tune-up. I had never seen the inside before, so was quite impressed with the whole concept of enclosed modules. The swing-out power supply was interesting--making it easy to work on and providing access to the bottom slugs of the IF transformers. Someone had written "Danger RF" on the back of the tuning adjustments for the RF amplifier and antenna sections--which I found odd. Fortunately the oscillator was pretty well aligned and a small tweak of the trimmers sufficed for all but one band. I ended up just changing the filter caps--a previous owner had installed a double 30 MFD can many years ago, so I replaced that with a couple 10 MFD electrolytics. The originals were 8 MFD. I also changed out the bleeder resistor which had drifted up from 65 K to several hundred K. I did not try and check any other parts, other than an inspection to see if anything looked burnt or was leaking.

After alignment, everything worked well on the radio and I was very happy with the quietness and ability to receive SSB and AM.

Norm


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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 12:00 am 
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inch for inch, the densest radio ever built, I had one a few years ago and loved it. Amazingly heavy for it's size, sold in an attempt to gain some elbow room in my shop, now I have another that needs some work, "running when parked :roll: .

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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 12:01 am 
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Location: Morris Plains, N.J. 07950
That's great that it works so well, Norm. Consider yourself lucky. A full recap on a BC-342 is a major job. One tip: I hope when you swung the power supply out, you saved and reinstalled all the spacers. If they're not there, the underside of the chassis can short out by making contact with metal on the power supply. In a pinch, wooden dowels can substitute for missing spacers. I'm sure you can figure out how I know this!

The area under the chassis and on the back of the RF deck is quite crowded, so installing new caps can be a challenge. The smaller mylar caps come in handy for this application. Pulling the three RF boxes to get at the caps inside is a major challenge, although nowhere nearly as bad as some people describe it.

It doesn't look like that one has been modified too badly. The "snout" in the lower right has been removed, and it looks like one of the jacks on the right-hand edge has been replaced with a toggle switch. I wonder what that switch does? The antenna connector on the upper left has also been changed out. At least no one installed an unsightly after-market S meter. Your plastic dial cover looks to be in good shape; they are often yellow and deformed.

Here are a couple of good videos on recapping a BC-342:

https://www.youtube.com/watch?v=0jaiebGjPJo

https://www.youtube.com/watch?v=ydd_JNQmcf8

Not only are BC-342 great performers, but they're living slices of history.


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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 1:12 am 
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Thanks, Joe. Yes, I did make sure all the spacers went back in place. I enjoyed the videos you posted. The switch below the speaker and phone jack just switches the audio between them and between the two RCA jacks below. I haven't determined what they do. This radio seems to work with the original caps and I don't plan on using it, so will probably leave it as it is. The plastic dial sheet with the line is quite deformed--but is in the correct place and there is a glass cover on the front. I replaced the #47 bulbs with LEDs so that there will be no heat in the compartment going forward.

Norm

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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 1:32 am 
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Location: Morris Plains, N.J. 07950
If you ever decide to go into the dreaded RF boxes, let me know. I found a few short-cuts and work-arounds that might help.

I have a real soft spot for the BC-342. In fact, whenever I see one for a good price at hamfests, I pick it up. To me, they are the quintessential military radio from WWII.


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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 3:08 am 
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Location: Southern Ga. zip 31768 US
I have one of those BC 342-N`s mfg. by Farnsworth that was said by the previous owner to have been used in the south pacific during the second world war. I purchased this radio about 10 years or a little longer ago and replaced what was needed, other than a few of those .05 caps that were way down at the bottom of those stated dreaded RF boxes (3) I think.
I never was able to figure out a way to get those out without taking this receiver apart as described, so I just left them in, all the rest of the caps like them (most) were leaky and were replaced. This radio was really a good performer in the ham bands I listened to but has been boxed up for several years now.
I think to save space they crammed all this really tight but heavy. Very nice looking receiver.
Rodney,,


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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 4:16 am 
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I'll have to take a look at what you guys are talking about with spacers on the power supply. I bought a 312-D with the AC supply that looks identical to the 342 and I removed the supply hinge pins to get the box out so I could replace the power toggle switch. Afterwards I just lifted the power supply box to align the hinges and screw the pins back in. I have no idea what spacers you guys are talking about. I'm hoping its a design change between yours and mine and I have nothing to worry about.


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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 4:25 am 
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Location: Morris Plains, N.J. 07950
The spacers are small cylinders that the screws go through to keep the power supply from hitting the underside of the chassis.


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 Post subject: Re: BC-342-N
PostPosted: Nov Mon 06, 2017 4:38 am 
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Besides the hinges, there are two long screws at the rear with spacers that screw into some posts on the supply to keep it from flexing when it is in the closed position--at least on my flavor of BC-342. The manual seems to imply that there were a number of different versions of the supply. The screws are offset from each other, one down beside the Mixer transformer and one out at the corner. You can see the corner one in my picture from the rear.

Norm

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 Post subject: Re: BC-342-N
PostPosted: Nov Wed 08, 2017 1:11 am 
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I see my 2 metal posts are there but no insulator spacers on the end. I think the only thing that saved mine from shorting out under the chassis was the 2 oil filled caps that were physically left in place. They acted as a spacer between the chassis and the top of the supply. But its still very close. I'll come up with something for the proper post spacers.


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 Post subject: Re: BC-342-N
PostPosted: Nov Wed 08, 2017 2:04 am 
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Check the surplus conversion manuals online; they have some simple mods you can do in the RF and audio section.

Thanks for sharing your post - seeing it made me drag out my BC-344 that's been sitting on the "pile" - can't help myself. :mrgreen:
Glad to see another one of these working!

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 Post subject: Re: BC-342-N
PostPosted: Nov Wed 08, 2017 1:44 pm 
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I seem to remember a discussion wherein someone said McMaster-Carr had spacers that would work.


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 Post subject: Re: BC-342-N
PostPosted: Nov Wed 15, 2017 9:01 pm 
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Location: Milwaukee,WI
My radio is a BC-312D but is probably close to the same as the 342 so I'll just continue this thread instead of starting a new one.

I am doing a replacement of all the micamold caps and there are I think 7 of them located on the 2 terminal strips under the chassis and above the power supply housing. Between faded dot colors and stiff wires in the way its difficult to read the values of those caps. To save me from more squinting and going back and forth between tracing wires, looking at schematic and pages of parts lists in the pdf manual, has anyone already done the hard work and identified the values of those caps? It would save me a whole lot of time and effort.


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 Post subject: Re: BC-342-N
PostPosted: Nov Sat 25, 2017 2:13 am 
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Duh. Luckily for me those caps turned out to be resistors in a mica cap looking body. So that means the only caps that didn't get replaced in mine are the ones located inside the RF units. I'll take my chances and leave them alone. Its a pain to remove the units and get at the caps.


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 Post subject: Re: BC-342-N
PostPosted: Nov Sat 25, 2017 3:29 am 
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I suggest at least measure those micamold/wirewounds; they should be 500 ohms. The RF chassis can be unscrewed and pulled up with the tube cap wires sliding through. The screen resistors also sometimes go out of tolerance and those can be accessed too. In fact, I've worked on three of these, and it's usual to find out-of-tolerance resistors.

Don't be afraid of separating those RF boxes, if you want to check parts; it's actually quite easy to slide them off the long flat tang that controls each unit's ceramic wafer switch.

Let us know how you progress! (I'm actually starting a fourth unit in this series, the BC344 low frequency unit).
cheers

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 Post subject: Re: BC-342-N
PostPosted: Nov Sat 25, 2017 1:28 pm 
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I watched a Youtube video on the RF boxes removal and taking out the long shaft was the easy part. Unsoldering all the leads on the top and back of each box are what I don't really want to tackle.


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 Post subject: Re: BC-342-N
PostPosted: Nov Sat 25, 2017 3:06 pm 
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FYI There are several other threads here about this radio; you may wish to search for those - lots of good info there.

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