Rare Canadian Bakelite SW Farm Radio PH-102 (same as Rogers Majestic RM-503), made around 1954 by Philips Canada, converted to AC, Serviced and Perfectly Working

In a Nutshell
Rare Canadian Short Wave Radio converted from Battery to AC Operation

Note added Oct.18, 2011:
I just bought another one (pict.s 32,33), leave it as a battery set and charge $50 less as for the AC converted one.

Introduction:
This Canadian PH-102 is a very rare radio. I just uploaded it to the radiomuseum (ref.1), where there only was a phantom picture. The radio was made by Philips for their Canadian subsidiary Rogers Majestic, who themselves made the same radio under the name RM-503 (see pict.28). The latter can also been seen at ref.2, where however it is wrongly dated as being from 1952, since the patent sticker goes up to 1956. Mine has as last year 1954 (pict.27), and the schematics (pict.s 29,30) can be found in the RCC (Radio College of Canada) files under 1953/54. Both radios exhibit a rare Union decal on the back (see above picture).
Anyhow, it's a beautiful bakelite radio, that has a unique front grille made from transparent lucite with the dial integrated, and two matching lucite knobs with brass brights. It is an all-wave receiver including 2 SW bands, with a 2-point tone control. Its only handicap today, 56 years after its birth, is that it is a farm- or battery set, needing an "A" battery of 1.5V and a "B" battery of 90V. To make it more attractive I built a custom battery eliminator (pict.s 21-24, 29, lower right, see techies), so it works now on 115V AC - and got a dial light (pict.31)! The modification can easily be undone and the original wiring (pict.28, lower right) is included in the sale.

Additional information:
ref.1: http://www.radiomuseum.org/dsp_modell.cfm?model_id=182867
ref.2: http://www.radioatticarchives.com/radio.htm?radio=8958

About my radio:
The cabinet is as shiny as bakelite is when it is just made. The radio was probably stored and not used because of the messy storage batteries. Also the 4 original Rogers tubes (pict.25) look unused and test like new. The radio's chassis is in very good condition and was thoroughly cleaned and electronically serviced. A battery eliminator for both voltages (1.5 and 90V) was integrated (see techies). The radio works with excellent sensitivity, selectivity and volume. Please e-mail me (Kris) for any questions, ich spreche Deutsch, je parle Français.

For the techies only:
I refer to pict.29, lower right. The A-battery eliminator uses the innards of a commercial DC-Adapter, the DC voltage of which should be chosen higher than the tube's heater voltages (1.5V) by the least possible amount. The resistor R₁ drops the voltage down to the required value; its value is dependent on the voltage mismatch, the number of tubes to be heated, and the heater currents and has to be determined empirically. Since the tubes are directly heated, any remaining ripple on the voltage will be audible, which is why the filter capacitors C₁ and C₂ should be chosen as high as possible.
The DC plate voltage of 90V is not far from the AC line voltage of 115V. Therefore a simple battery eliminator can be built without using a transformer. The B-battery eliminator uses one or more (in series or in parallel) cheap Christmas tree bulbs (120V/5W) to drop the voltage from 170V (=120V∙√2) to the requested tube plate voltage. For 90V plate voltage the (one) bulb is powered with 80V and glows only slightly, it's there also to protect the tubes from surge currents, since the resistance goes up with current and temperature. As is the case here, this bulb(s) can even serve as a dial light(s) (pict.31), since most battery sets don't have one. Filtering the B voltage is by far less critical, since the gain of a pentode like the 3V4 is only weakly dependent on plate voltage. So simple half-wave rectification and smaller filter capacitors C₄ and C₅ can be chosen, without risking to hear too much hum. The power plug of the radio has to be polarized, because no transformer is used. The cold end of the plug is not directly connected to the chassis.

Here are the specifications:

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