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Article #18981Re: VCR's sensitivity to UHF (limited VHF dynamic range)
From: Mike Butts
Date: Mon, 04 Apr 1988 17:21
Date: Mon, 04 Apr 1988 17:21
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2250 bytes
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
...!{sequent,tessi,apollo}!mntgfx!mbutts OR mbutts@pdx.MENTOR.COM
These are my opinions, & not necessarily those of Mentor Graphics.
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!tektronix!sequent!mntgfx!mbutts From: mbutts@mntgfx.mentor.com (Mike Butts) Newsgroups: sci.electronics,rec.video Subject: Re: VCR's sensitivity to UHF (limited VHF dynamic range) Message-ID: <1988Apr4.102120.89@mntgfx.mentor.com> Date: 4 Apr 88 17:21:15 GMT References: <1884@rayssdb.ray.com> Organization: Mentor Graphics Corporation, Beaverton Oregon Lines: 36