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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 4:43 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 10199
Location: Santa Rosa, CA
1. What fuse rating are you using? Slo-Blo?

2. When you say you "set" the Variac at 3 volts, I hope you measured that and didn't accept the dial reading?

3. Variacs are hard to set exactly at low voltage. A carbon brush rides on the wire turns and the difference between one turn and the next can be significant.

4. Some Variacs blow fuses on start-up regardless of load. https://antiqueradios.com/forums//viewt ... f=8&t=3973

Rich


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 5:11 pm 
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Joined: Jun Tue 23, 2015 4:37 am
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Location: SE Iowa 52626
Rich, W3HWJ wrote:
1. What fuse rating are you using? Slo-Blo?

2. When you say you "set" the Variac at 3 volts, I hope you measured that and didn't accept the dial reading?

3. Variacs are hard to set exactly at low voltage. A carbon brush rides on the wire turns and the difference between one turn and the next can be significant.

4. Some Variacs blow fuses on start-up regardless of load. /viewtopic.php?f=8&t=3973

Rich


Rich, the fuse was a 4 amp Fast Acting fuse....probably should have tried a 5 amp in it or even a 4 amp Slo-Blo. I measured the output with three meters and the dial on my variac does not turn easy thus it stays where you put it. Actually, this variac can be set to within .1 volt or less with no problem. I will read your link a bit later but right now I am on the run.

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 5:21 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 10199
Location: Santa Rosa, CA
Quote:
Actually, this variac can be set to within .1 volt or less with no problem.


Amazing!

Since variac brushes usually span at least a couple of turns, I wouldn't think you could get that accurate.

Image

Rich


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 5:36 pm 
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Joined: May Sat 30, 2015 11:49 pm
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Location: Keystone Heights, FL, USA 32656
IGot2P wrote:
Jeff, I saw that question about not realizing there was paper on the plexiglass...some people should not be in the gene pool. :)

Tonight was a completely different experience with the radio. Now I am not sure that my current power supply is causing any problem to speak of. When I first tried the radio with my current power supply I actually got a couple of stations (first time ever) on the very low end of the dial scale. Unfortunately, the stations were on top of each other and very garbled. There was some noise in it but not near like it was before. That radio is so "touchy" that if I touch anything, even the face, I get static, the station fades out, etc. I think that I need to go back to square one and clean every tube pin, check the coils, etc. and even re-solder some of the joints.

Don

Yes, funny, she took the paper off of one side and still couldn't see through the Plexiglas.

Sounds like some sort of progress, noise is good. Sounds like signal is leaking into the radio, not coming through the antenna circuits. Need to check resistances of coils, tuning caps, connections, etc.

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 6:09 pm 
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IGot2P wrote:
Not sure I can find a power resistor like that...Don


In the sub-ohm range, I've made power resistors using plain old bare steel wire from the hardware store. It comes in a 35-50 foot roll for a couple of bucks. I believe it's galavanized, as it solders fine.

This is just FYI, as I think a transformer is the right approach in this case IF your power supply is indeed bad.


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 6:41 pm 
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Location: Keystone Heights, FL, USA 32656
Maybe this: https://www.tubesandmore.com/products/t ... pen-25-vct.
The 10 amp one.

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 19, 2020 9:45 pm 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 720
Location: SE Iowa 52626
Rich, W3HWJ wrote:
Quote:
Actually, this variac can be set to within .1 volt or less with no problem.


Amazing!

Since variac brushes usually span at least a couple of turns, I wouldn't think you could get that accurate.

Image

Rich


Rich, I just posted a short video on Youtube at https://www.youtube.com/watch?v=5AUVHr3jlF8 that shows my variac in action. It jumps around some on me because I was both holding the camera and adjusting the variac but you will get the idea of how close it will adjust.

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 1:59 am 
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Joined: May Tue 30, 2006 4:46 pm
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Location: Santa Rosa, CA
Wouldn't have believed it possible!

Rich


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 2:40 am 
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Joined: Jun Tue 23, 2015 4:37 am
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Location: SE Iowa 52626
jrehkopf wrote:
IGot2P wrote:

Sounds like some sort of progress, noise is good. Sounds like signal is leaking into the radio, not coming through the antenna circuits. Need to check resistances of coils, tuning caps, connections, etc.


Well, here are the resistant results of the coils. I found it interesting that when I first checked the resistant of A1 to A2, A1 to A3, and A2 to A4 I got in the 30k range but then I checked them again a bit later after a thorough cleaning and they were totally open. Yes, I used two different meters both times with the same results. The coils were still in the circuit when tested both times. I don't have a clue as to what they should test but they all do test nearly the same.

Don


Attachments:
COILS.jpg
COILS.jpg [ 278.82 KiB | Viewed 1045 times ]
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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 4:35 pm 
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Location: San Rafael, CA. 94903
Three sets of what sounds like good connections. Two coils, four terminals on each.
73,
-marc


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 4:46 pm 
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Joined: May Sat 30, 2015 11:49 pm
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Location: Keystone Heights, FL, USA 32656
In the upper left edge of your photo I think are the Ant and Gnd terminals. What is the resistance measured between those two terminals? I think should be about 2 ohms.

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 7:02 pm 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 720
Location: SE Iowa 52626
jrehkopf wrote:
In the upper left edge of your photo I think are the Ant and Gnd terminals. What is the resistance measured between those two terminals? I think should be about 2 ohms.


You nailed it Jeff, 1.6 ohms.

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 8:17 pm 
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Location: Keystone Heights, FL, USA 32656
OK, like marc says, the coils measure good. I think this schematic is close. (excuse the drawing attempt on the 3 trimmers capacitors, I think this is how they are wired.)
Edited to add capacitors.
Attachment:
Liberty Elec 6.jpeg
Liberty Elec 6.jpeg [ 180.72 KiB | Viewed 915 times ]

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


Last edited by jrehkopf on May Mon 25, 2020 3:38 pm, edited 3 times in total.

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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 9:41 pm 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 720
Location: SE Iowa 52626
jrehkopf wrote:
OK, like marc says, the coils measure good. I think this schematic is close. (excuse the drawing attempt on the 3 trimmers capacitors, I think this is how they are wired.)
Attachment:
Liberty Elec 6.jpeg


After I finish cleaning all of the pins and contacts I will give it another try. I really think that it might have something to do with the center tap that is shown coming from the transformer. Of course, I do not have a center tap so I need to find out which wire it is and what voltage I should connect it to.

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Wed 20, 2020 11:29 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1379
Location: Keystone Heights, FL, USA 32656
At this point I am not sure what you are using for the A filament voltage supply. If DC try with A- connected to ground circuit; B- and C+ also connected to gnd. Then try with A- not connected to gnd, B- still connected to gnd.

Are C- voltages connected?

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Fri 22, 2020 5:52 am 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 720
Location: SE Iowa 52626
jrehkopf wrote:
At this point I am not sure what you are using for the A filament voltage supply. If DC try with A- connected to ground circuit; B- and C+ also connected to gnd. Then try with A- not connected to gnd, B- still connected to gnd.

Are C- voltages connected?


Jeff, after cleaning and putting everything back together I basically get nothing more than I had before. I have all the wires connected to my ARBE-III plus the two filament wires connected to my original DC power supply and I can only get one or two stations very faint on the low end of the dial (they are coming through the antenna). I have tried about every possible combination of connections with no joy. I still do not have the black wire connected but have tried it everywhere. I need to track it down and see where it really goes. Also, when I wiggle my 2nd AF tube it seems to change the reception somewhat plus causes static so I will have to take a good look at that socket and the related connections.

Yes, the C+ and the -4.5C are connected.

It is almost midnight thus I am not going back out to my shop tonight and tomorrow I have several errands to run so if will probably be late tomorrow when I get back to it.

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Fri 22, 2020 4:39 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1379
Location: Keystone Heights, FL, USA 32656
I went back and added some notations to the schematic I posted. Your photos of the coils really helped. I am about 90% sure the schematic matches your radio. I also listed the battery connections. I am pretty sure these are the correct connections:
Red=A+ 3v
Red=A-

Blue=B+ 45v
Pink=B+ 90v
Dk Green= B+ 135v
Yellow=B- and C+
Black=C- 4.5v
Brown=C- 9v

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 26, 2020 4:33 am 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 720
Location: SE Iowa 52626
jrehkopf wrote:
I went back and added some notations to the schematic I posted. Your photos of the coils really helped. I am about 90% sure the schematic matches your radio. I also listed the battery connections. I am pretty sure these are the correct connections:
Red=A+ 3v
Red=A-

Blue=B+ 45v
Pink=B+ 90v
Dk Green= B+ 135v
Yellow=B- and C+
Black=C- 4.5v
Brown=C- 9v


Jeff, we have stations...albeit not crisp and clear but I do have stations! I found that the capacitor in the gold box was way off so I stuffed it with a correct one. Also found a bad solder joint between the antenna and the first coil. I am still using my noisy power supply which I hope is causing a lot of the static and garbling. I should be getting my DC Step Down Buck Converter tomorrow (already have the six volt battery) and just maybe will be using it late tomorrow.

The stations that I am currently getting are all on the low end of the dial and seem out of place. For example, I am getting WHO Des Moines at about 25 on the dial but it is at 1040 AM which I would think would put it much higher than 25 on my dial. The dial is in relation to the variable condensers so it is not just dial adjustment problem. It also seems like the dial light is sucking too much power. I forgot to look to see if the amps go up when it is on but the volume certainly does go down so less voltage is getting to the filaments.

Oh yeah, I am only getting most of the stations at night which is quite normal as I am setting in what is called the Des Moines River Valley thus most all of my vintage radios act the same way.

Thanks for all of your help and I will keep you posted.

Don


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 26, 2020 4:58 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1379
Location: Keystone Heights, FL, USA 32656
Good to hear, great progress at last. You may know this but the radio may not tune much higher than about 1250. Also, low dial numbers = higher frequency. Can you list some other stations and dial settings?

If you have the nerve to try it maybe try adjusting the tuning capacitors to better track together. Set the small trim capacitors at a mid position. Tune in a station and then loosen the setscrews on the 2nd and 3rd capacitor shaft just enough so you can move the rotor plates. Hold the front tuner static with the knob and slightly nudge the other two rotors one way or the other with a chopstick to see if you can get the signal to get louder. This will be a touchy adjustment, tiny movement may cause big changes; be careful. Maybe tap, tap, tap with the adjusting tool instead of pushing.

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“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Back to the basic "basics" so bear with me
PostPosted: May Tue 26, 2020 7:22 pm 
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Posts: 14891
Location: S. Dartmouth MA 02748-1225 USA
According to the "schematic" note the quotes :roll: The radio is supposed to have trimmers for alignment of the tuning condenser sections. Shifting the rotors will reduce the overall rotation by what ever amount is done to achieve some sort of tracking. There is some risk of cracking pot metal rotors if they are potmetal...

Either at "0" or "100" set all the rotors the same.

Look for a station at "50" and align to that. If more stations and or sensitivity is greater above "50", choose "45" as the alignment and so forth...

The schematic seems to indicate that there were optional neutralizers, however if the RF coils are not tapped then these cannot be installed.

Further, seems that a poor solder joint held the radio back from initially performing. IMNSOHO re-solder everything,, even if it "looks" good. re-solder the pins of the tubes and tease the contacts of the sockets. Take a dead 4-pin tube or just its base, sandpaper the sides of the pins with very coarse sand paper in a circular motion, take that base and insert/remove at least 10 or more times for each socket. The roughened pins will burnish the socket contacts at the correct diameter of the pin, removing the tin oxide without removing excessive material at exactly the correct point of contact.

GL

Chas

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