Does anyone have some decent information concerning a parts list or parts specs. used in a Radiola 18. All I can find on this radio are some sketchy values, no voltages or wattages for parts.

Hi, Marty. I have a Radiola 18. When I worked on it, the Rider's schematic was sufficient: http://www.nostalgiaair.org/PagesByModel/317/M0040317.pdf

Maybe the filter caps in your power supply are OK? If not, you can replace them with either 160-V or 450-V caps.

What parts are you missing information on?
Doug

:Does anyone have some decent information concerning a parts list or parts specs. used in a Radiola 18. All I can find on this radio are some sketchy values, no voltages or wattages for parts.

None of the resistors show the wattage and none of the capacitors show voltage ratings. Did you replace some of the filter caps with electrolytics? I would NEVER run a radio with 80 year old capacitors.

:Hi, Marty. I have a Radiola 18. When I worked on it, the Rider's schematic was sufficient: http://www.nostalgiaair.org/PagesByModel/317/M0040317.pdf
:
:Maybe the filter caps in your power supply are OK? If not, you can replace them with either 160-V or 450-V caps.
:
:What parts are you missing information on?
:Doug
:
::Does anyone have some decent information concerning a parts list or parts specs. used in a Radiola 18. All I can find on this radio are some sketchy values, no voltages or wattages for parts.

Well, the maximum voltage shown on the schematic is less than 100V. That's why I said 160- or 450-V caps should be fine. I normally just stock 450-V e-caps and 600-V film caps.

I'd have to remove my chassis from the cabinet, which is a pain, to refresh my recollection about the set. But I think the reisistors are wire-wound - no reason to replace them unless they are open. If any have to be replaced, you can estimate the maximum voltage across them by studying the schematic, and figure the wattage from there (double for conservatism).

And, I seem to recall that most of the caps are mica - no reason to replace those either unless they are shorted.

I did not replace the filter caps. Many old sets like this are OK, and I bring them up on a variac to be sure. But if you wish, go ahead and unpot the original filter caps and replace them. The values are shown on the schematic, and you can just use 450-V caps. I would use electrolytic filter caps for replacement even though the originals weren't e-caps. Suit yourself.

:None of the resistors show the wattage and none of the capacitors show voltage ratings. Did you replace some of the filter caps with electrolytics? I would NEVER run a radio with 80 year old capacitors.
:
:
::Hi, Marty. I have a Radiola 18. When I worked on it, the Rider's schematic was sufficient: http://www.nostalgiaair.org/PagesByModel/317/M0040317.pdf
::
::Maybe the filter caps in your power supply are OK? If not, you can replace them with either 160-V or 450-V caps.
::
::What parts are you missing information on?
::Doug
::
:::Does anyone have some decent information concerning a parts list or parts specs. used in a Radiola 18. All I can find on this radio are some sketchy values, no voltages or wattages for parts.

There's an article on a Radiola 18 restoration on this site by Bill Jeffrey. Might be of some use.

http://www.nostalgiaair.org/References/Articles/Singles/Radiola18-2.htm

Ken

Have you guys seen the article/thread on this months page by Bill about old capacitors. Very informative. Some of the Atwater collectors have updated their sets with modern hidden components which provide better reliability and performance. That is what I am looking for in my RCA set.

:There's an article on a Radiola 18 restoration on this site by Bill Jeffrey. Might be of some use.
:
:http://www.nostalgiaair.org/References/Articles/Singles/Radiola18-2.htm
:
:Ken

:Have you guys seen the article/thread on this months page by Bill about old capacitors. Very informative. Some of the Atwater collectors have updated their sets with modern hidden components which provide better reliability and performance. That is what I am looking for in my RCA set.
:
::There's an article on a Radiola 18 restoration on this site by Bill Jeffrey. Might be of some use.
::
::http://www.nostalgiaair.org/References/Articles/Singles/Radiola18-2.htm
::
::Ken

The filters in the 1927-1930 light socket Radiolas are 600 volt paper condensers, well potted (vaccum potted, in fact) into their respective cans. They very seldom fail, excepting, perhaps, in the few sets with UX-250 output tubes. On these sets the condensers are operated with a much smaller safety factor (the plate supply to the 250 in some of these units is 450 volts at modern line voltages). In the usual run of Radiola sets, however, the safety factor is more than ample (after all, the sets with UX 171 outputs have a 175 volt plate supply, and the UX 245 units 225 volts at modern line voltages). As for resistor ratings, well, the grid leaks (where used) don't dissipate any power, and so a 1/4 watt or 1/2 watt, 2.2 meg units will suffice. A one watt unit will be adequate for the voltag dropper in the detector circuit, and a five watter will be overkill for the voltage dropper for the RF amplifiers.

When in doubt, calculate power dissipation in the circuit using Ohm's Law, E=IR (Voltage = Current (in amperes) X Resistance), I=E/R, R=E/I. Once you know current through and voltage drop accross a resistor, it is a simple matter to calculate the power dissipated in it, just multiply voltage by current (in amperes) to determine watts.

If you cannot find a value for a resistor in a vaccum tube power supply circuit, it is generally safe to assume that most tubes are operated at the rated voltage and current levels specified in the RCA oe Sylvania tube manuals. Knowing the voltage available at the output of the power supply filter, and the rated plate or screen voltage and current of a given tube, one can easily calculate appropriate dropping resistor or voltage divider values. In resistance coupled amplifier circuits, it is always safest to use the values in the RCA tube manual's resistance coupled amplifier charts.

Sorry for this lonng-winded post. I know that this information will be obvious to many on this board, but hope that it can be of use to some of the new collectors who may not yet have a strong electronics background.