i found this old transistor radio in a box of junk and changed the battery holder and a few caps and it plays although it seems to be a poor radio.i know little about these as my collecting area is 20s and 30s sets but wonder if its anything collectable or just a piece of junk.butch

I believe the 8-BT-7J is one of RCA's earliest transistor radios. Very collectible and not junk.


(picture courtesy radiotvnut)

Dave

you might need to look into it further. see why its not performing. looks pretty cool. if you dont want it...

it is the same as the one in the pic but not as shiny or scratch free.i guess i'll play around with a little but i remember buying a similar one in the 50's and it never picked up many stations out here in the sticks either.butch

Hey Butch,

That's a good looking early RCA---maybe a little TLC on yours & you could set it on that great Zenith Chairside you're almost done with ! I sure like that model...

I have an RCA 9-BT-9E from the same time-frame---after electrolytic cap replacement and repair of poor PCB trace connections around tuning cap, its a pretty good performer for a six transistor set...

John

I have a half dozen of the 8-BT units; two each with Turquoise, pink, and grey back covers. They use RCA 2N140, 2N139, and 2N109 Transistors for the converter, IF, and audio output, two IF's, and a decent size metal variable tuning cap.

I've recapped them all, leaving the originals in place, and mounting the new ones under the circuit board. Once recapped, IF's retuned, and the trimmer on the antenna gang of the tuner peaked, they offer what might be expected of a mid-fifties 4 Transistor set in performance. Nothing to get excited about, but their good looks make up for it, lol.

Butch, recap all 5 of the Electrolytics, tune the IF's and antenna trimmer, and maybe shine the case with a plastic polish.

On my sets, I've left in the original battery snap connectors (designed for round Transistor batteries with a connector on each end), and added a modern dual snap connector for using current 9 volt batteries.

i looked a little closer and saw i'd missed the 2 10 uf lytics that sit side by side.i changed those and it made a great improvement.i'll have to check the resistors for any that drifted next.i also need to pick up a 100uf cap all i had on hand were 220 uf but one of these seems to work well as i tried 2 in series to get close to 100 and then just 1 and can't tell any difference so i doubt the 100uf will matter much.i'll see what some mirka 5000 grit liquid sanding gel will do for the case .i have some small buffing pads that work on my cordless dremel tool at low speed.thanks for all the encouragment its making this a fun project.butch

The 220 uf should be fine. It is likely a battery bypass cap and may even maintain performance better than 100 uf as the battery ages.

Dave

i have 1 ques. the cap out on the dogleg by the speaker in this set is a 6 v. 30uf lytic it looks out of place and before i replaced it it had been done before, looking at the poor soldering job.it doesn't seem right to me but then what do i know?butch

The cap by the speaker should be an axial unit, black in color, rated at 100 Mfd, 10 volt.

i guess next to the speaker was a poor discription.this one is next to the 2- 2n109 transistors on a little square of circut board out on the end.there are also 3 resistors next to it.a 100ohm 220 ohm and a 4700 ohm.i am thinking of getting a schematic for this so i have some idea what i'm talking about.i know it is a simple set but i'm kind of simple when it comes to these as all i've ever worked on are the older vacuum tube types.butch

Hey Butch---the schematic is on page 115 of the 1957 Beitmans. There used to be a site that offered the entire Beitmans for free download, but if you'd like, PM me an e-mail & I'll send page to you...

The cap you're referring to is C12 & is on schematic as a 25 uF...

Was really surprised to see that this was only a 4-transistor set---was wondering why Fifties made that comment about 4-transistor performance ! Didn't realize that RCA made anything less than 6 at that time...

John

I have a 9-BT-9J that I recapped and tuned up. This one adds both an IF and AF amp, and has three IF cans and two audio transformers, over the previous 8-BT design. The Ferrite antenna was also changed, from a rectangular shape to a slightly longer rod style. Physically, the case is the same width and depth, but just slightly taller.

The reception difference IS noticeable, and it's a very good performer.

i polished it up and aligned it and it does play a lot better but it still isn't much for pulling in weak stations however i think it does well for what it is.i took a pic but its kind of dark it looks like the one dave posted above except with a small chip on the center left.

Looks good, butch.

Given the color of the dial retaining screw, I presume the back half of the case is either grey or turquoise.

The models with pink colored backs had red colored retaining screws.

Also, the upgraded models had a chrome strip with "RCA Victor" printed on it at the vertical midpoint of the grill, a silver dial background, and an earphone jack.

Hey Butch---looks like it cleaned up well ! Glad you got it going...

John

yes the back is gray and i did get most of the scratches polished out.it does look way better than when i started.i owe a big thanks to john for sending me the schematic .i figured out right away that i was injecting the if signal at the wrong point and a correct alignment helped a lot.
this project has got me wondering if i should try fixing some of the other old transistor sets i have held onto over the years .ive been so absorbed in the old tube type i've igored these and wonder if it would be appropriate to post a pic of them to get an idea of which are the type that you guys find worth having.i don't know a newer solid state type from the older ones myself with looking inside for ic chips.i do know my dads old royal 1000 transoceanic is transistor as it was purchased in the early 60's and of course it says all transistor on it.butch

What, I don't get credit for opening your eyes to change all the caps, lol?

This is an antique radio board...There's nothing that restricts the displaying and discussion of crystal or Transistor sets.

Any Transistor radios you have with Civil Defense marks would have a value, in that the newest of them would be 50 years old. Those with IC's are only worth fixing if they have a practical value for you.

i'll have to dig around in my junk sheds the only one i had in the house was a zenith 755.it is one of those leather covered sets which although it is transistor it doesn't look very collectable its kind of a common looking am only portable.oh i almost forgot
thanks for reminding me to change all the lytics fifties.it seems like once i got up in my 60s i don't remember things that good anymore.butch