I need to find out where I can get a battery eliminator, or how to build one for my Silvertone model 1923. Using 9 volt rechargeables seems to be too much of a pain to put together & keep recharging, so I would rather go this route if someone knows how I could do it. Thanks.
Regards, Larry

Larry, here's the Cadilac at $150: http://www.arbeiii.com/

AES sells a kit, K-101A, for $56:
http://www.tubesandmore.com/

By the way, I have an ARBI power supply, which works great. I also have "inherited" one of the battery-eliminator kits from AES.

I didn't assemble the AES kit, somebody else did. And, my version of the kit might not be identical to the current version. BUT, the AES power supply causes a minor hum/noise on both of the radios I've used it with, while the ARBI causes no hum.

I've tried shunting additional caps across the AES unit's caps -- no joy. It's possible that the AES unit, which unlike the ARBI, isn't in a metal enclosure, is radiating RFI. But when I move the AES power supply around, it doesn't seem to affect the noise.

I'll add a testimonial to Doug's advice. I have three commercial battery eliminators (including a kit from AES and an ARBE III). I also get a noticeable hum from the AES kit, but it works. I have another model which I ordered on-line (it's a lesser version of an ARBE III) and it's OK but doesn't have the voltage ranges an ARBE III has. If you're going to work with TRF battery radios on a regular basis, save yourself aggravation with the lesser models and buy the ARBE III. It's worth every penny.

Jeff

Hi

A comment about hum from these radios.. Early battery radios use audio interstage transformers. These transformers can pick up hum from a power supply transformer even a foot or more away. Try rotating your power supply to see if hum changes.

You don't need an exact 135 volts to an output tube. Down to 90 volts should still operate.

Norm

:By the way, I have an ARBI power supply, which works great. I also have "inherited" one of the battery-eliminator kits from AES.
:
:I didn't assemble the AES kit, somebody else did. And, my version of the kit might not be identical to the current version. BUT, the AES power supply causes a minor hum/noise on both of the radios I've used it with, while the ARBI causes no hum.
:
:I've tried shunting additional caps across the AES unit's caps -- no joy. It's possible that the AES unit, which unlike the ARBI, isn't in a metal enclosure, is radiating RFI. But when I move the AES power supply around, it doesn't seem to affect the noise.

Would shielding help on the eliminator that hums?

:Hi
:
: A comment about hum from these radios.. Early battery radios use audio interstage transformers. These transformers can pick up hum from a power supply transformer even a foot or more away. Try rotating your power supply to see if hum changes.
:
: You don't need an exact 135 volts to an output tube. Down to 90 volts should still operate.
:
:Norm
:
:
:
::By the way, I have an ARBI power supply, which works great. I also have "inherited" one of the battery-eliminator kits from AES.
::
::I didn't assemble the AES kit, somebody else did. And, my version of the kit might not be identical to the current version. BUT, the AES power supply causes a minor hum/noise on both of the radios I've used it with, while the ARBI causes no hum.
::
::I've tried shunting additional caps across the AES unit's caps -- no joy. It's possible that the AES unit, which unlike the ARBI, isn't in a metal enclosure, is radiating RFI. But when I move the AES power supply around, it doesn't seem to affect the noise.

Ed, shielding the battery eliminator might help some, but maybe not really solve the problem. The ARBE is pretty quiet and, contrary to what I said in an earlier post, it's not housed in a metal case -- it's in a plastic box with an aluminum lid.

Norm talked about the audio xfmrs in the receiver picking up power line hum. I guess this would be through induction. However, this does not seem to be the cause of the noise from my AES kit. First, it's not a pure hum, more like hash. Secondly, the amplitude of the hash doesn't seem to change as the eliminator or receiver is moved around or turned. And thirdly, if the interferance were getting directly into the radio from the power line, why doesn't it happen when using the ARBE?

My theory is that the battery eliminators produce RF, which causes noise in the set. The eliminator ckts use linear, 3-terminal voltage regulators, which have many transistors and zeners inside, switching and doing there devilment. The bridge diode ckts for each of the three voltages, A, B, and C, are busy chopping up the 60-Hz AC waveform, producing harmonics galore.

And then multiple windings on the same transformer core are used to supply AC for the A, B, and C supplies. So harmonics on any one winding can get induced on the other windings.

Then, we have up to six conductors running from the eliminator into the radio, all of which can carry RF and inject it into undersirable places.

Personally, my theory is that these eliminators need RF chokes in their ouput. I don't know what's inside the ARBI box because the lid is fastened with one-way screws, but my "used" AES unit has no noise suppression other than the usual DC filter caps.

:Would shielding help on the eliminator that hums?

One more comment on the AES battery eliminator kit.

I traced the worst problem to the C supply. The C voltage isn't really regulated -- it's basically just a bridge rectifier followed by one zener and a pot acting as a voltage divider.

What I found was that when the radio's filament current was turned up, the C- would all of a sudden develop all kinds of noise and no steady voltage. My theory is that transformer is too puny, with poor voltage regulation, and the C voltage jumped back and forth around the voltage of the zener. Naturally, this would make the radio go wild.

My kludge fix was to slap a 4-uF cap across the C terminals on the AES eliminator. I could have replaced the zener with one with a lower voltage.

Let me repeat my earlier disclaimer. I "inherited" my AES battery eliminator, so their current design may be improved. My sense though is, that there is no assurance that AES actually uses and tests all the antique radio stuff they sell. Maybe they're all guitar players.