Fringe & non fringe area TV's..

[colly0410]

I know some set makers made TV's with extra sensitivity & flywheel line sync for fringe area's, but what other improvement's (if any) did they incorporate?

[Terry]

I think that's about it!

Usually just an extra IF stage plus, as you say, possibly the addition of flywheel sync but I can't think of anything else.

I will be interested to see if anybody can come up with specific examples of other extras, though.

[ppppenguin]

I don't know if they narrowed the IF bandwidth for a fringe set. Trading resolution for reduced noise. The prewar EMI TRF sets such as the 702 could be aligned for different reception conditions, from wideband with low gain for local to narrow band with high gain for fringe.

[colly0410]

Never thought about narrowing the video bandwidth for fringe reception, be a bit like some communication receivers that had switchable bandwidth for distant stations..

[Murphyv310]

Hi.
Murphy had "A" versions of the V310/320. Like others it had line flywheel sync and tweeks to the IF stages, it also had gated AGC whereas the non fringe models were straight sets. I've a 310A and two 320A fringe sets and they all have a slightly lower HF response, maybe tuned for a narrow bandwidth for more gain.

[colly0410]

Would gated back porch AGC work better that the more usual mean level AGC in fringe conditions on 405 lines?

[Murphyv310]

Mean level agc was never a good option, in fact a straight Tuner/IF stage was a better option. Both the Pye V4 & the Murphy fringe sets with gated AGC work very well with low signals. Once lower than the threshold of a signal that gives AGC action the RF/IF stages run at maximum gain.

[colly0410]

Read somewhere (Practical Television or similar I think) that they had 'swamp area' TV's that were for use only in strong signal area's near TX's, can't remember what make/model, I presume it would be a band 1 channel 1 only TV made as cheap as possible for the London area, although would've worked OK in Belfast & other channel 1 area's..

[peter scott]

See this thread: https://www.vintage-radio.net/forum/show...p?t=150590&highlight=murphy&page=2

Peter