PILOT BS648

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PILOT BS648. This attractively designed radio was issued in 1948. It has seven wavebands - one medium, one long, and five bandspread on the short wave bands. These bandspread ranges are as follows:- Band 1 :- 13 to 16 mtrs Band 2 :- 19 mtrs Band 3 :- 25 mtrs Band 4 :- 31 mtrs Band 5 :- 40 to 128 mtrs Band 6 is the medium wave :- 200 to 550 mtrs Band 7 is the long wave :- 900 to 2000 mtrs The set is designed to be operated on a.c mains 110 - 130 volts, or 200 - 250 volt ranges,
40 to 100 c.p.s. The valve range includes :- 6SH7 (r.f amplifier); 6K8GT (frequency changer); 6K7GT (i.f amplifier); 6Q7GT (double diode triode amplifier); 6V6GT (power amplifier); 5Z4G (full-wave rectifier) There are 4 scale lamp bulbs (6.2 v @ 0.3amp m.e.s). My brother bought this for me - it originated from a waste tip in East Suffolk. There was no sound eminating from the energised loudspeaker, although the field coil was o.k. The problem was that the 6V6GT valve was duff - a replacement cured the problem. In the past, someone had mixed the 6 range octal valve range with the Mullard type ("red- E series"). The Mullard range are not the direct equivalent to the valves used in this radio! The 270k ohm resistor connected to the anode of the 6Q7GT valve had gone well out of tolerance, and two of the metal foil Hunts "Mouldseal" audio coupling capacitors had began to lose their plastic shell coating. I replaced them with polypropylene types. There are yet many wax-paper condensers in the radio, that will require replacement in due course, as they are horrendously "leaky". This will be carried out sometime in the future. There was a mechanical problem in this radio to be rectified - the closed metal speaker grille was loose in the cabinet. When I removed the loudspeaker and the baffle from inside the cabinet, I discovered that the wood screws securing the baffle and grille had been inserted in to over-sized holes in the cabinet. There had been previous attempts by someone to drill a number of fixing holes in the metal grille. I made a note of the right combination of holes that I required to fit the grille. In order to repair the holes in the cabinet for fitting the screws to secure the baffle & grille assembly - I filled the holes with araldite. I then coated the wood screws with industrial grease (thus preventing them from being glued in the holes in the cabinet). When the araldite adhesive had dried to its "plastic" stage, I then placed the screws in to the holes in the cabinet. Eventually the adhesive cured fully, and then the screw holes could be used to secure the grille & baffle assembly.