Just picked up a 1930s Battery operated Coronado

[vortalexfan]

Originally Posted by Electronic M

Both at once...

Are you sure the two batteries should be connected in parallel? Because I'm only getting 1.5 volts connecting them that way...

I've also tried connecting 2 sets of D batteries in parallel and I'm only getting 1.4 volts, so not even close to the correct amount of volts needed to power the radio's filiments...

[vortalexfan]

Well I was able to rig up a temporary battery rig for my radio and it works...Sort of.

I hooked up my signal generator up to the radio and it picks up the 456 kHz IF Signal fine (all though it picks it up all across the whole dial and not just around the 550 area of the dial), and I tweaked the IF cans and surprisingly enough they are peaked where they are supposed to be, I tried adjusting the Oscillator and Antenna adjustments on the tuning capacitor and they didn't seem to make any difference and the 600 kHz oscillator adjustment is under the chassis so I couldn't adjust that.

But I can't get it to pick up any radio stations I can't even get it to pick anything up from my signal generator tuned to various stations on the AM Band, hooked through the antenna, and the antenna coil tested fine when I tested it.

Any ideas as to what may be going on?

[Electronic M]

Originally Posted by vortalexfan

Are you sure the two batteries should be connected in parallel? Because I'm only getting 1.5 volts connecting them that way...

I've also tried connecting 2 sets of D batteries in parallel and I'm only getting 1.4 volts, so not even close to the correct amount of volts needed to power the radio's filiments...

Note I didn't advise you to put the batteries in parallel....I only advised you HOW to connect them in parallel.
The trouble with using standard alkaline D cells to supply the 2.2V filaments is that new alkaline cells are 1.5V so parallel will not give you enough voltage and series will give you too much (unless you use used batteries that are down to ~1V ). The only advantage of parallel connection is that the batteries will last longer.
One thing you could do for the filaments is connect the batteries in series and build a LM317 circuit to regulate 3V down to 2V...A filament rheostat is another solution.

Got an oscilloscope to check if the converter or oscillator tube is oscillating? And do you have a decent length of antenna wire 15-40' hooked up? If you have an antenna and the IF works then either the local osc is dead or the RF path between the antenna and the Mixer/Converter is bad....If you passed IF down the antenna and it didn't seem attenuated in comparison to injecting it at the 1st IF then that favors the Osc being dead.

[vortalexfan]

Originally Posted by Electronic M

Note I didn't advise you to put the batteries in parallel....I only advised you HOW to connect them in parallel.
The trouble with using standard alkaline D cells to supply the 2.2V filaments is that new alkaline cells are 1.5V so parallel will not give you enough voltage and series will give you too much (unless you use used batteries that are down to ~1V ). The only advantage of parallel connection is that the batteries will last longer.
One thing you could do for the filaments is connect the batteries in series and build a LM317 circuit to regulate 3V down to 2V...A filament rheostat is another solution.

Got an oscilloscope to check if the converter or oscillator tube is oscillating? And do you have a decent length of antenna wire 15-40' hooked up? If you have an antenna and the IF works then either the local osc is dead or the RF path between the antenna and the Mixer/Converter is bad....If you passed IF down the antenna and it didn't seem attenuated in comparison to injecting it at the 1st IF then that favors the Osc being dead.

No but someone else on here said to connect 2 D cells in parallel to get the voltage I needed for my filaments, you just happened to reply when I asked about how to connect batteries in parallel.
Anyways Rechargeable NiMH batteries are 1.2 Volts which if I connected 2 of those together I would get 2.4V which would be the correct voltage I need for the tube filaments, and they make NiMH Rechargeable D cells that are as high as 12,000 mAh, which would be more than enough juice to power the filaments.

I'm guessing the oscillator isn't running because the tubes aren't getting enough filament juice.

[dieseljeep]

Originally Posted by vortalexfan

No but someone else on here said to connect 2 D cells in parallel to get the voltage I needed for my filaments, you just happened to reply when I asked about how to connect batteries in parallel.
Anyways Rechargeable NiMH batteries are 1.2 Volts which if I connected 2 of those together I would get 2.4V which would be the correct voltage I need for the tube filaments, and they make NiMH Rechargeable D cells that are as high as 12,000 mAh, which would be more than enough juice to power the filaments.

I'm guessing the oscillator isn't running because the tubes aren't getting enough filament juice.

Those tubes aren't that easy to source. They only used them for few years.
The 1C6 can be replaced with a 1A6.
I checked over my 2 volt battery set. At the time, I built the power supply using a transformer from a scrap VTVM. I didn't have a regulator chip at the time, so I just used discrete components.

[decojoe67]

Battery radios are the most underated old radios around. When I first started collecting I too didn't give them a second look with all those ragged wires and clips hanging out of the back. The truth is they're unique looking sets and perform very well once restored. You also don't get AC line interference, so the audio is clean. The only drawback with the wooden models is that there's usually no dial lamp, or, at best, a dim one.
Unfortunately, very often, either a surge or an attempt at hooking an AC line to them was not uncommon. Usually what happens is an instant blow-out of all the tubes. In my experience of dealing with portable battery radios, it's a 50/50 chance that the tubes are good. I've replaced the tubes on these many times.

[vortalexfan]

Originally Posted by decojoe67

Battery radios are the most underated old radios around. When I first started collecting I too didn't give them a second look with all those ragged wires and clips hanging out of the back. The truth is they're unique looking sets and perform very well once restored. You also don't get AC line interference, so the audio is clean. The only drawback with the wooden models is that there's usually no dial lamp, or, at best, a dim one.
Unfortunately, very often, either a surge or an attempt at hooking an AC line to them was not uncommon. Usually what happens is an instant blow-out of all the tubes. In my experience of dealing with portable battery radios, it's a 50/50 chance that the tubes are good. I've replaced the tubes on these many times.

I agree this is a very nice looking set and is also supposed to be based on one of the best designed sets Arvin made at the time, the Phantom Series.

And I think once I recap this set, and get some proper Rechargeable D cells and a good battery clip for this set I think I should be able to get this thing going.

[vortalexfan]

Originally Posted by dieseljeep

Those tubes aren't that easy to source. They only used them for few years.
The 1C6 can be replaced with a 1A6.
I checked over my 2 volt battery set. At the time, I built the power supply using a transformer from a scrap VTVM. I didn't have a regulator chip at the time, so I just used discrete components.

I'm curious, if I were to use some 1.2V NiMH rechargeable D batteries to power the filaments in this radio (2 1.2V batteries in series would give me 2.4V roughly) what kind of diode or what size of dropping resistor would I need to drop the extra .3V to get the voltage down to the 2.1V I need for the tube filaments?

Or would it not matter in this case?

Thanks for your help.

[Kevin Kuehn]

Originally Posted by vortalexfan

I'm curious, if I were to use some 1.2V NiMH rechargeable D batteries to power the filaments in this radio (2 1.2V batteries in series would give me 2.4V roughly) what kind of diode or what size of dropping resistor would I need to drop the extra .3V to get the voltage down to the 2.1V I need for the tube filaments?

Or would it not matter in this case?

Thanks for your help.

Any silicon diode such as the 1N400 series will drop around .6V which in my book will be close enough. I'd go so far as to suggest that two Alkaline batteries in series with the same diode will be close enough too. If you're worried about a few tenths of a volt, then put two diodes in series and when the batteries run down you can short across one and get any remaining life out.

[vortalexfan]

Originally Posted by Kevin Kuehn

Any silicon diode such as the 1N400 series will drop around .6V which in my book will be close enough. I'd go so far as to suggest that two Alkaline batteries in series with the same diode will be close enough too. If you're worried about a few tenths of a volt, then put two diodes in series and when the batteries run down you can short across one and get any remaining life out.

I've got several 1N4007 diodes would those work?
Would I tie the diode across the negative or positive lead of the battery clip?

[fixmeplease]

Ive done a few of these 90V but the filament was 1.5v. Anyway I use 60 AA batteries for 90V power. I have soldered in connections for 45V too for other radios. I doubt the AA's cost much more than the 9V ones but you have to solder holders together and yes more time involved. About every 3 years +/- 1 they need replacing if they are a good brand.

I like the sound of the battery radios. They dont have much static type sounds as they arent hooked to your homes power supply. If your fortunate enough to have a long wire antenna that will increase the sound too. My outdoor antenna is about 90 feet long.

[dieseljeep]

Originally Posted by fixmeplease

Ive done a few of these 90V but the filament was 1.5v. Anyway I use 60 AA batteries for 90V power. I have soldered in connections for 45V too for other radios. I doubt the AA's cost much more than the 9V ones but you have to solder holders together and yes more time involved. About every 3 years +/- 1 they need replacing if they are a good brand.

I like the sound of the battery radios. They dont have much static type sounds as they arent hooked to your homes power supply. If your fortunate enough to have a long wire antenna that will increase the sound too. My outdoor antenna is about 90 feet long.

Reminds me of what I did in the mid-50's. I would dig through the trash bin behind the TV shop for battery packs for a Zenith TO or similar. The "A" side was usually dead, but the "B" side was good for about 75 or so volts.
That side was usually sealed in tar and lasted quite a while.

[fixmeplease]

American ingenuity!

I did forget to add that the smaller voltage battery will often just last hours as they have draw. The 90 volt pack will last for the life of the batteries. I did buy a cheap brand of AA's and I got what I paid for, they lasted about a year.

[dieseljeep]

Originally Posted by fixmeplease

American ingenuity!

I did forget to add that the smaller voltage battery will often just last hours as they have draw. The 90 volt pack will last for the life of the batteries. I did buy a cheap brand of AA's and I got what I paid for, they lasted about a year.

On a side note and slightly OOT, it always amazed me that anyone would buy a battery only tube radio. "B" batteries were never cheap!
I'm referring to the time when most homes had electricity. Portable, battery only radios were made until about 1956.
Three way portables were only about $5 to $8 dollars more and you can use them all year.

[jr_tech]

Originally Posted by dieseljeep

On a side note and slightly OOT, it always amazed me that anyone would buy a battery only tube radio. "B" batteries were never cheap!
I'm referring to the time when most homes had electricity. Portable, battery only radios were made until about 1956.
Three way portables were only about $5 to $8 dollars more and you can use them all year.

In my case, it was for safety... as a kid, I was always taking my radio into the bathroom, a battery only set with no cord was much safer. “B” batteries were great xmas and birthday gifts

jr