OldRadios

This radiogram was made in 1963 and the only information on the set was that it was a “Dual”. The radiogram has a Garrard deck with a stereo crystal pick-up. It has separate FM and AM tuners – which I think is unusual for a set of this period. It has a multitude of inputs and outputs for speakers and tape decks. Perhaps the most unusual feature is that each half of the stereo amplifier can be used independently for AM, FM and the gramophone. Thus, you could, in principle, be listening to AM with your left ear and FM with the right.

I think the idea was so that you could have speakers in different rooms with different stations on each. The set was in very nice condition, so I spent a bit of extra time cleaning up the chassis.

Technically, the FM tuner consists of an ECC85 VHF RF/Mixer/Oscillator followed by two EF80 the first being an IF Amp, the second being a limiter. FM detection was carried out by germanium diodes. The AM section consisted of an ECH81 Mixer/Oscillator followed by EBF89 IF Amp/Detector. There was also an EC91 triode valve carrying out some unknown function (I couldn't locate the model, so I couldn't find the circuit diagram). Maybe the EC91 was the local oscillator, and the triode of the ECH81 was a buffer – but I didn't trace the circuit, so I don't really know.

The stereo amp consists of two identical amps using half of an ECC83 and an EL84. Power supply rectifier was the EZ81, now made by JJ valves, who also make all of the audio valves in this set. Also made by JJ, but not in their web catalogue, is the EM84 tuning indicator used in this set.

The set uses Philips intermediate frequency transformers. These are very small indeed, and when taken apart reveal minuscule windings. The ferrite cores for these are stuck to the ends of the brass tuning adjustment screws. I love the way these perform so well and the neat design. Most unfortunately, I don't love the way the piece of ferrite falls off the brass adjusting screw, causing all sorts of amusing problems. In this case, the AM section of the set would only work if the set was upside-down.  In the past I have gotten into all sorts of trouble attempting to drill holes to remove the loose piece of ferrite and glue it back on to its ferrule. This time, I simply let the ferrite fall back into place, then secured it with beeswax. This means that the transformer is no longer adjustable, so that IF alignment is no longer optimum, but the set works well enough, even so. I am trying to contact a German supplier of valve IF transformers, but so far no luck. Plan B is to make my own. (The chassis has been given a good clean!)

The original Ronette pick-up was replaced with another which looked identical, but wasn't. The new pick-up is presumably metric, whereas the original was imperial. We couldn't resist playing some old 45s from the 60s and were rewarded with pure nostalgia – the sound of a 45 being played on a crystal pick up. Loud, harsh, everything true to the original, reminding me of the cheap plywood and vinyl record players costing 20 quid that we used to play in our teens.