Ultra V1770 - my first telly and Im struggling

[Exiled Yorkshireman]

Thanks Mike.

[Mike Watterson]

Note the sound IF can be almost peaked (it's wider band than AM Radio, so 20 kHz wide), but the video wants more than 3 MHz (vestigial sideband), so I think the IFT must be slightly staggered, rather than peaked which is too narrow. Easy with a noise source and spectrum analyser, or tracking gen and spectrum analyser. It was historically done with a wobbulator. The scope X sweep frequency modulated the IF generator and diode detector fed the Y axis. I had a Meguro or some such Japanese one for AM/FM radio for a while with built in swept IF generators and marker oscillators to mark centre and band edges.

No doubt you can magic the DDS Sig gen you have and a scope (or PC scope via sound card) to do the same thing.

Alternately for the video (audio is straight forward), you roughly put all the video IFTs in alignment and then fine tune using the test card gratings. Back in the day I only had the test card to align the IFs.a

[Exiled Yorkshireman]

There's a fairly comprehensive alignment procedure documented in the manufacturer's service data, Mike, so I think I'll start with that first. Thanks for the tips though, I may well need them.

[Mike Watterson]

I hope the maker's alignment points out that there are two "peak" positions for each coil and only one is correct. If the upper coil is tuned with core at bottom and lower coil has core at the top then the coupling is increased and this is usually wrong. Normally the  peaks where the  top coil has core at top and bottom coil has core at bottom is correct.

   

See diagrams here on 3rd post. Link to 2nd post on Radio Museum.

Indeed it's excellent you have manufacturer's literature as the R&TVS and Trader sheets don't detail alignment, just quote the frequencies.

Of course your IFs are around 38 MHz rather than 10.7 MHz or 455 kHz, but the principle is the same.

[Exiled Yorkshireman]

Yes, Mike, the alignment instructions give starting positions for the cores. Mind you, they don't tell you why. Thanks for that excellent piece of information.

[Mike Watterson]

Yes, Mike, the alignment instructions give starting positions for the cores. Mind you, they don't tell you why. Thanks for that excellent piece of information.

Ha!

Well, that's good!

[PerdioPal]

The elastic strands from "knicker elastic" are ideal for cores.

[Mike Watterson]

The elastic strands from "knicker elastic" are ideal for cores.

I'd imagine so.

I look forward to further progress reports.

[Exiled Yorkshireman]

Well, I think I've gone as far as I can without a real signal source. I'm going to build a Hedghog L and take it from there. I'll report back as and when, although it may take some time. Especially as I have two cancers to deal with.  Mind you, working on the old telly has been helpful in taking my mind off the fact,

[ppppenguin]

I reckon it's worth spending a fairly modest amount of money to get a fully built Hedghog from Stephen (Freya) in Cornwall.

Thank goodness Frank in Ireland designed the Hedghog, now that Darryl has stopped making the Aurora. Both are excellent turnkey solutions to providing signals for 405 line TVs. Both use the Motorola (later Freescale, then NXP) MC44BS373 modulator chips. These had been declared obsolete some years ago but supplies seem to be still available.