Fault finding in an RF Signal generator.
I was given a dead 'Advance E2 Radio Frequency Signal Generator' and I decided to get it working and I thought you might be interested to see the process I went through to get it going again.
Self oscillatory oscillators can be the very devil to fix as either an open circuit or a short circuit can stop them dead and that's without thinking about including any other manmade or man-introduced faults or simply out of spec components. The only good thing one can say about having to fix a self oscillatory oscillator is at least the faults in front of you, it's not (normally) being influenced by any other external force, although once or twice with high powered RF oscillators (200kW) I've had the feeling that Old Nick was having a hand in things.
So, if you start off with the knowledge that the fault is in front of you then all you've got to do is work out just where it is, as it turned out this fault wasn't as difficult to find as I originally thought it was going to be, but it was compounded by miss information and the fitting of incorrect replacement parts.
If you do have to fault find in a self oscillatory oscillator circuit then probably the easiest option is to remove all power from the faulty oscillator and then drive its circuits with another test oscillator and work through the circuit with the test oscillator and an oscilloscope.
If your interested in Radio then pleases have a look at my other videos, you'll find a No 19 set. Spy Radio, Vintave radios and a series called About Radio in which I talk through every component in an old GEC radio.
Here's the full link to 'About Radio ... Part 1 by Andy Davies. Removing the chassis.'
[ Ссылка ]

If you're interested in this series of videos then I recommend that you also take a look at Rick McWhorter's channel.
This is the full link to one of the videos by Rick McWhorter
[ Ссылка ]
(AllAmericanFiveRadio) Do download his book, it's free but the information is priceless! Rick has put a huge amount of effort and a lifetimes worth of experiences into his videos, I think you find them interesting and entertaining, but be warned, you'll get hooked! I have.

Thanks to 'frsimem' (Paula) from the UK Vintage Radio Repair and Restoration web site for pointing out that the ECC82 has a B9A base whereas the ECC91 has a B7G base and to 'WME bill' Bill m0wpn also from the UK Vintage Radio Repair and Restoration web site for helping me out with the replacement valve.

Kind Regards ... Andy gw0jxm

свернуть