[rec.video] VCR's sensitivity to UHF

mbutts@mntgfx.mentor.com (Mike Butts) (04/05/88)

 In article <3230001@hpindda.HP.COM> chikarma@hpindda.HP.COM (Sanjay Chikarmane) writes:
> ...
>While its reception of the VHF channels is very good, I find that
>it is virtually unable to tune in to the UHF channels. I can receive
>these channels quite well on my TV, ...
>

While we're on the subject, I've had trouble with limited dynamic range on **VHF**
on two current VCRs.  On a new Quasar (Matsushita) unit, and on a new JVC unit, 
both middle-priced and both with "digital" (i.e. synthesized) tuning, I've seen 
serious grainy-ness (i.e. video noise), which looked like a weak or mistuned signal,
due to an overly **strong** signal.  This is only on some VHF channels, not all.

The signal source was admittedly stronger than most: a multi-element beam on the
roof looking at the towers, about 5 miles away.  (The beam is to eliminate ghosting,
not, obviously, to increase signal strength.)  I found that the signal was much 
improved with an attenuator.  Across the supposed 20db range of a Radio Shack variable 
attenuator, I can get grainy-ness at either end, too strong or too weak.  
In the middle it's nice and crisp.  Awfully poor dynamic range, if you ask me.  
I also observed the UHF weakness others have mentioned, so I had to kludge up a split 
un-attenuated bypass path for my UHF.

Neither the synthesized Sony monitor/TV, nor the 1983 analog-thumbwheel-tuned 
Magnavox (Matsushita) VCR, has these problems.

I hope someone else can improve their reception with these pointers.

P.S. I love the JVC VCR, otherwise.

 
-- 
Mike Butts, Research Engineer         KC7IT           503-626-1302
Mentor Graphics Corp., 8500 SW Creekside Place, Beaverton OR 97005
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These are my opinions, & not necessarily those of Mentor Graphics.