17-04-2012, 04:46 PM
I don't have a wobulator, so I use a "Frequency modulated sweep generator" 
Basically, a wobulator consists of an oscillator than can be swept, and another oscillator that does the sweeping. I have plenty of oscillators, so hook them all together. A wobulator would take much less space, but wouldn't look as cool...
Hacker advise against peak tuning, but it will get the job done.
It might be whiskers - unfortunately, when a whisker makes contact, it might cause a small amount of leakage rather that the dead short we've come to expect. It just depends. In that R707 I did recently, only the first transistor in the module had any obvious leakage (a few 10s of K-Ohm IIRC), but it was enough to upset it when used in AM mode, where said transistor is the oscillator. So, I'm in the habit of treating them first - you can't apply logic until you *know* that there is no funny business going on...
I've tried lining these up in the past, and have never succeeded in getting the RF alignment spot-on on both wavebands.
Oh, and suspect any ceramic disc capacitors that are square (with coloured lines to mark their value). These things pretend to be resistors - or worse, they sometimes pretend to be resistors! Only last night one nearly got me, but I'm wise to their evil ways now
Basically, a wobulator consists of an oscillator than can be swept, and another oscillator that does the sweeping. I have plenty of oscillators, so hook them all together. A wobulator would take much less space, but wouldn't look as cool...
Hacker advise against peak tuning, but it will get the job done.
It might be whiskers - unfortunately, when a whisker makes contact, it might cause a small amount of leakage rather that the dead short we've come to expect. It just depends. In that R707 I did recently, only the first transistor in the module had any obvious leakage (a few 10s of K-Ohm IIRC), but it was enough to upset it when used in AM mode, where said transistor is the oscillator. So, I'm in the habit of treating them first - you can't apply logic until you *know* that there is no funny business going on...
I've tried lining these up in the past, and have never succeeded in getting the RF alignment spot-on on both wavebands.
Oh, and suspect any ceramic disc capacitors that are square (with coloured lines to mark their value). These things pretend to be resistors - or worse, they sometimes pretend to be resistors! Only last night one nearly got me, but I'm wise to their evil ways now
