13-03-2012, 09:38 AM
For all that I got this working I was disappointed with it as it needed a stupidly large aerial to pick up even strong signals; 300W from 9 furlongs away with nothing worth talking about in between. Yorkie brought his over which seemed about the same but I still thought it ought to be better.
With the recent talk of making new backs I was prompted to have another look at it.
The first thing I did was check the IF alignment. This seemed quite a bit out as when I first connected the sig gen there was hardly anything coming out of the speaker but when I'd finished it was uncomfortably loud. The sound quality now seemed better but not the sensitivity.
I couldn't do the RF as the cap trimmers look like they've had some sort of caps soldered on. Besides that there's no calibration mark due to the drum on the tuning capacitor being a replacement.
I then tried swapping the EF39 for one out of my Ferguson and it then worked much better. The Fergy seems perfectly happy with the 'duff' valve.
I don't know if it gives a clue to its maker but the IF cores stick of top and bottom rather than being accessed via holes in the back of the screening cans.
- Joe
With the recent talk of making new backs I was prompted to have another look at it.
The first thing I did was check the IF alignment. This seemed quite a bit out as when I first connected the sig gen there was hardly anything coming out of the speaker but when I'd finished it was uncomfortably loud. The sound quality now seemed better but not the sensitivity.
I couldn't do the RF as the cap trimmers look like they've had some sort of caps soldered on. Besides that there's no calibration mark due to the drum on the tuning capacitor being a replacement.
I then tried swapping the EF39 for one out of my Ferguson and it then worked much better. The Fergy seems perfectly happy with the 'duff' valve.
I don't know if it gives a clue to its maker but the IF cores stick of top and bottom rather than being accessed via holes in the back of the screening cans.
- Joe
