Quote:
Originally Posted by paulsherwin
It seems a bit of a palaver when sig gens can be bought for almost no money. Alternatively you could build a single transistor oscillator using a scrap IFT and align to that - there's no need to align to precisely 465kHz so long as all stages are aligned to a common frequency. You don't even need to modulate the signal if you measure the DC voltage at the detector.
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Yes, it's true Paul - signal generators can often be had for little money.
There's recently been a working Advance E1 in reasonable cosmetic condition listed twice with a starting price of £10.00 but no bids. Heavy, large, old, but internally it will be pristine. (Collection only due to size and weight). Trouble is, that many who want/need a signal generator tend to be novices at the early stages of setting up a workshop, so probably won't have other equipment to check the generator for accuracy or waveform etc, such as a frequency counter or 'scope. One thing tends to lead to another, and instead of the generator being an aid to aligning a receiver undergoing restoration, it becomes a project in its own right.
The circuit that is the subject of this thread can be simplified by omitting the output stage and that option was in the original design though I omitted to show that earlier, so I've attached it below. Just two ICs, two controls, the crystal resonator and filter. But you're right of course - it's possible to peak up the IFs without a signal generator, and I rarely find that IFTs have been tampered with on valve radios, though the same can't always be said for transistor sets. I think mixer/oscillator stages tend to pose more of a problem.