[Dark High]

Thanks for the advice Texasrocker, I have been very careful and I do ask a lot of questions. Maybe a short writeup about the basics of checking circuits and other helpful tips for us newbies would be a good sticky for the forum.

I have a couple of resistors that don't read what their suppose to read, I haven't isolated them yet from the circuit and checked it without being wired in. I have a question about resistors, if one is out of range, what would you expect to hear or whatever from the radio. Would I notice if one was out of range?

One of the things that I'm having trouble with right now as I check all the resistors and capacitors is identifying which one I'm testing. I look at the parts sheet that shows me where in the radio it is, but there are also a lot of other "parts" that look the same in the same spot in the radio. The schematics help some on tracing which one is which, but it can be very confusing.

I think I'm getting all my Am stations, though some are kinda feint. I'm going to do some finishing up with replacing some rubber parts and re string my dial cord. Are the fins in or out on the tuning wheel when positioning the string for the first time? Is "in" all the way at the bottom of the dial and "out" the top or right of the dial?

Thanks,

Jeff

[morzh]

I have a couple of resistors that don't read what their suppose to read, I haven't isolated them yet from the circuit and checked it without being wired in. I have a question about resistors, if one is out of range, what would you expect to hear or whatever from the radio. Would I notice if one was out of range?

One of the things that I'm having trouble with right now as I check all the resistors and capacitors is identifying which one I'm testing. I look at the parts sheet that shows me where in the radio it is, but there are also a lot of other "parts" that look the same in the same spot in the radio. The schematics help some on tracing which one is which, but it can be very confusing.

Jeff

Jeff

About resistors and caps:

1. ALWAYS check your parts when the power is OFF and it has been OFF for awhile.
2. The ONLY guarantee you are having a real reading is when the part is isolated from the rest of the circuit: for both types it is achieved by unsoldering one end. The other may stay connected.
3. With resistors, if the value you are reading before you isolated the part, is noticeably higher than what it is supposed to be, it is a sure sign of the part being bad.
The reason is, the rest of the circuitry is in PARALLEL with the part, and the ONLY thing it can do is to LOWER the reading, so if it is higher than the part is WAY OFF.
Still, unsolder one end - this will take the guesswork out of the process.

4. With capacitors it is quite uncertain while in circuitry, and you are likely to have unrealistic reading unless it is disconnected.

5. I don't know the old tolerances, but I would allow 5% for resistors and 10-20% for capacitors, as this is what it is today. (I mean, there are 0.1% resistors and sub-1% NPO/COG capacitors, but those are not one would use in a radio anyway).

6. Even if your old paper capacitor works, it is likely to actually gain capacitance (mine were 2x-3x times the nominal value) and develop some leakage. The common wisdom, even if all is working, is to replace them all, with possible exception of mica types, as mica is a mineral and does not age so badly. But Electrolytics and papers should go.


My own experience (small enough with antique tube devices, as I restored just one radio, but then I am an EE with 30 years industry experience, and done some tube amps when I was a kid, in 70-s) is: all my resistors (they were carbon type) have gone up in value up to 2x - 2.5x times, and it is bad, as it will screw up your DC regime, and all paper capacitors were 2x-3x the value, and some were asymmetrical when measured with regular C-meter, which indicates a leakage.

Mike.

[Dark High]

I'm still working on the radio and I've come across a new problem and I'm not sure I can fix it.

There isn't much to listen to on the AM band. I'd really not giving it much thought till now that I've got the radio playing and trying to tune in stations. I ran through the AM stations in the car last night checking to see whats on and it's slim pickings.

Oh well, it's still fun to have this older radio working, even if there's not much to listen to. I guess I should look into a AM modulator so I can play my own stuff.

-Jeff

[morzh]

Well, I am lucky: though I do have 4 or 5 stations, fairly weak, they'd be of no much interest to me otherwise, but one station is local, in Lakewood NJ, and is called "good times oldies" or something to that effect; it is off the chart strength-wise, and I barely rotate the volume to have my speaker booming. It plays mostly rock-n-roll, 40-s, 60-s, 70-s and it's great music, and clear enough to listen to.

Before I even repaired it I was afraid of the same predicament - I know AM is fairly deserted these days, when everyone seems to be on the UHF FM.
But I guess, God in his infinite grace decided to plat an AM Station in Lakewood, few miles from me, just to reward me for my sufferings.

[TA Forbes]

Your 40-180 is a 7 tube/3 band set. When you do get it right, which I am sure you will, it will sound better and get better reception than your car radio.

From where you live you should easily pull in stations from Atlanta at night, assuming that you outfit your set with a good antenna.

Additionally, with your two shortwave bands you should be able to pickup many overseas broadcasts, especially at night.

[Radioroslyn]

God is good! For a treat you can tune in 740kc at 10pm and hear a couple of old radio shows out of Canada.If you are still up at 11pm tune up to 900 and hear some more.I've been thinking about building a home broadcaster.Have got some interesting tubes to use, was thinking of using an 829B for the rf final. http://www.radiomuseum.org/tubes/tube_829b.html Full till it will make about 80watts of rf but not going to run it anywhere near full output. For the modulator was thinking of a 815 http://www.radiomuseum.org/tubes/tube_815.html Just because it's a cool looking tube. It's similar to a pair of 6L6's one one bottle. 6AQ5 for the oscillator and a 12AU7 for the low level audio.With 250-300v it should run 10w or so. One of these days I'll get around to putting it together.
Terry