RCA-Victor Floor-Mounted Battery Set (‘Farm Radio’)

[Gerry O’Hara]

I recently completed restoring an RCA-Victor Model 97BK ‘Farm Radio’. The set was given to me by someone at Maple Ridge who used to have it in ‘1930’s period décor’ room, but it had since been relegated to the garage and now they needed the space and wanted the set to go to a ‘good home’. It is now working very well after re-capping (papers and electrolytics replaced) and new bias cells fitted – no tubes were replaced. It’s a 7 tube set (no rectifier of course) with an RF stage and push-pull output, so it is quite a ‘potent’ performer.

The cabinet was in a rather distressed state on arrival, however, I decided not to strip it all: only the top was completely re-finished, the sides and front just touched-up with stain pens and carefully rubbed smooth with fine steel wool, leaving the original lacquer finish intact where it was still adhering well to the wood. The sides of the cabinet (which are not seen too much anyway) were given several coats of dark-tinted lacquer (to hide some of the imperfections), as were the base, speaker uprights and the edge of the cabinet top to act as contrasting highlights. The front was given a couple of slightly-tinted coats of lacquer and the top sufficient to tone the colour with the front panels. The entire cabinet was then given several coats of clear matt-finish lacquer (this tends to be more ‘accommodating’ to a slightly imperfect underlying finish than the semi-gloss I usually use). The result is a nice-looking radio…

This chassis has several bias batteries fitted needed in addition to the filament (2v) and late supply (135v) batteries. If you look at the chassis photo you can see a pack of 6 x AA cells at the right hand side providing 4.5v and 9v bias for the audio stages – these are my ‘modern’ replacement for two 4.5 volt cells originally fitted to the two chassis-mounted plugs you can see wires connected to near the battery pack. Underneath the chassis there are 4 button-cells for AGC and first audio tube grid bias – see photo (these and the AA cells will last for several years as there is virtually zero current draw on them). So, this set needed a total of 10 batteries fitted to work! The original ‘bias cells’ under the chassis would have been 1 volt each, so I replaced the pack of three of these with only two 1.5v alkaline ‘button’ cells to give the desired 3 volts, with a ‘button’ cell replacing the single bias cell in the grid of the first audio stage.

Mechanical work undertaken on the chassis included freeing the tuning mechanism, which was seized completely – I used WD40 to free/clean it and then applied thin machine oil to the mechanism to keep it running smoothly.

This is the most complex battery set I have tackled so far, as most are only broadcast plus one short wave band. By the time it was manufactured (I understand around 1938) most sizeable communities in North America had mains power, so there was little need for such sets. Canada was almost alone in manufacturing large battery sets like this one – still having a market on the Prairies and in more remote/smaller communities, however, most battery sets being produced from that time onwards were ‘portable’ ones – the iPods of their day I guess. Also, you tend to find that large battery sets were not used as much as mains-powered sets due to the expense/inconvenience of buying batteries (they were switched off when folks were not actually listening to the radio as opposed to just being left playing in the background) and therefore can tend to be in better condition – sometimes with the original tubes fitted – being set aside as soon as mains power was available and a mains-powered set purchased (maybe only a few years). So this model is a bit of a ‘last bastion’ for its genre.

The photos show a neat little power supply I designed and made for this radio (and other battery sets I have kicking around) – subject of a separate posting if anyone is interested.

Click on the photos for a larger image.

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[Dan Walker]

You did a great job on this one,,,,it looks very very nice inside and out..Thats a project you should be proud of.
I have several battery sets and they are different to work on Once again good work nice job,,,,, Dan

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