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telstar 14th Jun 2021 1:32 pm

Strad 511
Hi, at long last I finally sorted the fault on the Strad 511 radio. The cause of the fault was the valve base for the 7C7 audio pre - amplifier. It had become tarnished inside the socket, so I gave it a good dose of WD40. This eventually cured the fault. It was causing poor connections including hum. When measuring voltages on the anode it made a sound like it was the grid of the valve. This was the only socket that had this problem, the others being O.K. So I gave these others the WD40 treatment
It was initially confusing to work on the radio as it varied from the layout on the later model on Trader 1014. One of the large resistors across the main electrolytic capacitors measured 12.6 K ohms instead of its designed 10 K ohms. This metal resistor had lost all of its colour code and yet the first resistor (after the 7Y4 rectifier) still measured 180 ohms (but lost its colour coding).
Most of the carbon resistors in the radio had exceeded their tolerance limits (30%), and this included grid stoppers.
The wax capacitors were replaced with modern ones, but the electrolytics were the only ones that did not require replacements.
I also decided to give the loudspeaker wires a longer replacement.
Still some work to do on flattening the back card, and the whistle effects on BBC Radio 4 L.W.

telstar 15th Jun 2021 1:10 pm

Re: Strad 511
1 Attachment(s)
Here is a photograph of the Strad 511 radio.
I bought this from an outdoor stall at Leeds Market when radios were sold there in the 1990's. There are no radio dealers there now, only a stall for record players.
You don't see many of these radios, but I remember seeing a picture of a Strad 511 in one of my dad's service sheets, and this prompted me to buy the radio.

MALC SCOTT 15th Jun 2021 5:11 pm

Re: Strad 511
I have the Rent-A-Set version of this model.

Electronpusher0 16th Jun 2021 5:53 pm

Re: Strad 511
Malc just beat me to it, I also have a rent-a-set version, see this thread


telstar 17th Jun 2021 1:27 pm

Re: Strad 511
Hi Malcolm & Peter.
Good to know that you have the Rent A Set version.
There is also a Rolland version I believe (unless that is the one)
It is a wonder that Beamish museum do not have exhibits of Strad radios at their place (since it is not far from where the radios were made)

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