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Old 10th Apr 2021, 11:01 pm   #3
Gabe001
Octode
 
Join Date: Oct 2019
Location: Stockport, Greater Manchester, UK.
Posts: 1,646
Default Re: The taming of the shrew - the defiant "Defiant"!

.... And this was very underwhelming. The good news was that the lamp limiter was behaving as it should. I also had very faint reception on both bands (mw and LW).

At this point however, I had 3 problems

Volume was very low, even on gram
Sound was distorted
HT about 40v too high

In a nutshell, the ac2/Pen was low emission, and all the resistors were very much out of tolerance, so they all needed replacing. The paper caps would have to be changed too. The collectable Plessey 1uf metal cap measured 4uf with my meter so that had to be replaced too. In essence, I spent a day replacing all passive electrical components, put a new mains lead, earthed the chassis and cleaned the waveband switch. The volume control was very crackly at first but seems to have sorted itself out after some use.

Meanwhile, Jerry sent me a good ac2/pen. Things improved a lot. Volume came up and a lot of the distortion was corrected. HT was still high but closer to what it should be. This was unsurprising as the uu5 is more efficient than the original uu3. I was tempted to try and look for a UU3 but I'm not sure it would have been happy with 350v on the plates. In the end I used 2 470ohm 5w resistors to get the voltage down to where it should be. They don't get particularly hot.

I was almost there, but not quite. I was still unhappy with the sound quality.

The speaker voice coil was rubbing and I needed to recenter it. Never having done it before it took me a few hours. Things aren't perfect but the set sounds better now.
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