[winkydink]

Hello

First off thanks to everyone who help me last year with my slew of radios. The gifts were delivered for Christmas and they were a big hit !

I have a 1948 model 48-200 that I am working on. I need some help fine tuning the set.

Some background. I purchased this set from a repair person in Delaware who did much of my recapping last year. I only purchased the chassis. I have since found a case, but alas there is no antenna. The set has been recapped and also has been aligned by Radiotiques.

In looking around the web, I stumbled across a link to make a homemade loop antenna for these type of radios.

http://antiqueradios.com/forums/viewtopi...&highlight=

I followed the instructions and my results are shown in the image below. I used 28 gage wire which I purchase from Radio Daze. (http://www.radiodaze.com/product/13594.aspx )

One other complicating factor. Although the radio was purchased in about 2 months ago, I only had the opportunity to open it up the other day. I discovered that the speaker cone had been ripped during shipping. I repaired the cone using a techique found on this forum using glue and tea bags and the result is also shown.

I also have not checked to see if any tubes are weak.

Now the problem. I can tune stations in, but they are not sharp. Now to me if this were a "speaker" problem (because of the repaired cone), I would expect buzzing but not a lack of sharpness.

I also know that getting the antenna right, is very important. I have created a circumerence the same as the inside of the radio and have 17 loops. I tried counting the number of loops for a 48-200 and 46-200. Can anyone tell me how sensitive this is . If I am over or under by a loop or two, would this cause some distortion ?

What other things can I check for (I will test the tubes). Do I need to try to re-align (I have a signal generator).

I am going to try very hard to trouble shoot (and hopefully solve) this with the phorums help.

As always suggestions are welcome.

[Radioroslyn]

Now the problem. I can tune stations in, but they are not sharp.

What do you mean???
The # of turns on the loop will not cause distortion but will cause low sensitivity. If your loop is working correctly it should have a nice peak in sensitivity when the adj the trimmer on the tuning condenser around 1400kc.
GL
Terry

[winkydink]

7estatdef

can you point me to an older post or web article or youtube video which describes (in general) how to adjust the trimmer on the tunning condenser.

Still green here and trying to learn some things with out screwing up my radio too terribly.

Thanks.

[Radioroslyn]

Well the simplest way to figure it out is that one of the wires from the loop goes to it.( the trimmer) Tune dial to a station near 1400kc and then adj trimmer for max volume. Should peak near middle of the range of the screw. Not all the away in (if so then take a turn off of the loop) or all the way out (Add a turn to the loop) till your in the middle. Perfect!!
GL
Terry
ps r u in PA??

[winkydink]

The trimmer screw was very nearly all the way tight. When I tighten the screw the volume did get louder, but it tightened all the way before I believe it would peak.

My conclusion would be that I need to remove a loop and try again, as recommended by 7estatdef. I will try that in a day or two.

Yes Terry, I am in PA (State College)

Thanks

-Jim

[codefox1]

Yup! Almost there.

[winkydink]

Here is the latest update.

Upon the suggestion of Jeff from Radiotiques I also tested to see if the repaired speaker was a problem. So I desoldered connections used aligator clips and tested using the speaker on a "junk" Philco 47-204. The sound was very good. This is where I have stopped.

I still need to remove a loop and adjust the trimmer for max volume, so that the screw is in the middle of the range. I also need to see if I can easily remove the speaker from the 47-204. I also don't know if this speaker will fit in the 48-200 case.

Lots of unknows, but I am making some progress.....

[winkydink]

I have managed to remove the speaker from my "junk" 47-204. The speakers look to be the same size with one exception. The speaker from the 47-204 mounts via a bracket to the top of the chassis. (see picture).

The speaker on the 48-200 mounts via 2 screws at the front of the speaker. I am not sure if this speaker will fit in the 48-200 because of the bottom bracket. It looks like it is welded or soldered on. Does any one know a safe way of removing the bottom bracket in case I need to [without damaging the speaker]

Also the 47-200 speaker was connected to the radio via 3 wires. Positive and Negative, and then a 3rd wire as shown in the photo. What is this extra wire ? Another ground ( ???? )

The speaker on the 48-200 only seems to have 2 wires, though I will check when I take the damaged speaker out. Anyone have a suggestion as to what to do with the 3rd wire ?

Lastly a question. Since it seems like the distortion was caused by the torn [and then "fixed"] speaker. Is it possible that the speaker would be OK after a period of time, and that it is "stiff" because the glue and tea bags that I used for the repair ? Would it losen up if it were played for a while and sound better ? I am just curious if anyone has any experience in this area ?

[Steve Davis]

Jim, I would use a pair of pliers and bend the brackets until they break off. What I wouldn't do is saw, file or grind or anything that could create metal particles that could possibly get into the voice coil slot.

Steve

[winkydink]

Well it turns out that the speaker on the 48-200 was attached by a home brewed method of using the 2 screw holes at the bottom of the speaker, with non philco supplied brackets.

I looked back at a photo of a 48-200 that I restored and gave away for christmas and the speaker is not attached that way.

There are holes in the 48-200 chassis for the bracket on the 47-204 speaker and it fits like a glove. So that problem is solved.

The final issue I have is that 3rd GREEN wire which was attached to the chassis on the 47-204 at 1 end and to an inner connection point near the cone on the speaker.

Q: should I attache this green wire the same way it was connected on the 47-204 ?????

Thanks again.

[winkydink]

New speaker is in the 48-200 and the red and blue wires have been resodered and shrink wrap tubing was applied.

I still have the green wire issue. The photo shows that the green wire goes to different place on the speaker than the red and blue wire.

I did not notice this before, but there is a cut off green wire on the 48-200 leading to somewhere in the chassis, but I am not sure where.

Logic would seem that I should just connect the two green wires together and problem solved. But I would like to know what the green wire is for and what it should actually connect to.

Additionally, the radio is working great. Nice and clear voices, sound, music and very easy to tune. The home made antenna (now off the cardboard) works well and is ready to be attached to the inside of the case.