I was looking at the Brian Cuff subforum and after reading through it, wonder if his GEC 8161 Mirror Lid TV recreation ever got finished? Its appears he gave it to somebody else.
I searched more generally than VRAT and found nothing.
Its appears he gave it to somebody else.
Indeed, when Brian realised he had little time left, he passed it onto Mike @cathovisor to finish. Mike collected it from Brian back in Aug 2016, no idea what became of it. I've often been curious of its fate too.
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Hi all,
It is safely in secure storage wrapped in a multitude of blankets at the moment until such time as I can devote my energies to it: at the moment my priority is making a living as a member of the so-called "gig economy". My two pre-war Baird sets are also standing silently awaiting their turn.
The last thing I acquired for the GEC - and I'm not sure if it was mentioned in the thread - was a genuine 12" GEC electrostatic black and white tube for it, which allowed me to dispense with the CV1085 mixed-persistence CRT that was in use. Somewhere I have paperwork relating to GEC CRTs of this era (I have a feeling it may have been a dealer publication) and notable was that the 16" tube had a very short life indeed, being classed as obsolete by 1939 so a 12" tube may have even been a period mod for the set.
Before the pandemic I had made contact with an owner of a BT8121 and had arranged to do exacting measurements of the coils in the receiver chassis as I know Brian was having trouble getting a sensible gain/bandwidth compromise - however, I have also seen it mentioned that it was very unlikely this set's vision receiver was flat to 3 MHz; 2 MHz being more likely.
There are always going to be compromises with this set as part of the receiver was contained in a modified version of a more conventional radio chassis: which of course, we do not have. Similarly, a degree of liberty can be taken with the overall sensitivity of the set as we're no longer eking out every last microvolt from AP now.
Rest assured, it is safe, well protected and it is not going anywhere other than where Brian wanted it to go eventually, which is Dulwich. I'm sure Brian wouldn't want me to give up on it, but I'd wager he'd want me to get cracking on it!
Hi.
Was not David Boynes involved with getting all the measurements for Brian and a lot of stuff sorted for him. I also sent him a load of period bases and bit and pieces for this project.
Hope it doesn't languish under a blanket too long, we are all getting older and I for one would have like to see the end result!
Cheers,
Trevor.
MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member
Hi.
Was not David Boynes involved with getting all the measurements for Brian and a lot of stuff sorted for him. I also sent him a load of period bases and bit and pieces for this project.
Hope it doesn't languish under a blanket too long, we are all getting older and I for one would have like to see the end result!
He was indeed, Trevor. It's another David I know who has the 12" version and it is he whom I shall be visiting when circumstances allow, notebook and pencil in hand. I'm acutely aware of us all getting older; I have a funeral to attend on Tuesday, whilst yesterday I was chatting to a (staff) colleague who will hit forty years' service at the BBC in December - he was in the dormitory room next to mine when I was a trainee in 1984 and I remember D Block like it was yesterday!
Dunno about you, but as I watch the snow fall here I'd rather be under a blanket!
One of the problems Brian encountered was achieving sufficient bandwidth in the vision IF amplifier. It was determined that my BT9121 and the Brian's BT8161 employ similar coils in the vision IF amplifier. In fact the response curves are similar, or should be. It is the position of the vision carrier that differs. In the BT8161 the 4Mc/s carrier is positioned on the lower flank of the response curve and in the BT9121 the 6Mc/s vision carrier is on the upper flank.
The BT8161 sound IF is 500Kc/s and as the vision IF is aligned to the upper sideband there is a wide trough between the vision and sound. In the BT9121 the sound IF is 2,5Mc/s.
Till Eulenspiegel.
One of the problems Brian encountered was achieving sufficient bandwidth in the vision IF amplifier. It was determined that my BT9121 and the Brian's BT8161 employ similar coils in the vision IF amplifier. In fact the response curves are similar, or should be.
This was one of the reasons I bought a very different sweep generator to what Brian was using in order to determine exactly what was going on. Of course, the thing came from a vintage radio event so was faulty, but I think I can get it going again: we used to use an identical model (but modified by the BBC to lock to field drive) for sweeping the frequency response of cameras.
