The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: "Steve Andrew"
Subject: Re: 10.7MHz video demodulator
X-Newsreader: Microsoft Outlook Express 5.00.2615.200
Date: Sun, 19 Jan 2003 22:33:47 GMT
NNTP-Posting-Date: Mon, 20 Jan 2003 09:33:47 EST
Organization: BigPond Internet Services (http://www.bigpond.net.au)
Michael Black wrote:
> John Woodgate (firstname.lastname@example.org) writes:
>> I read in sci.electronics.design that Steve Andrew
>> wrote (in <6OjW9.2073$m47.10729@news-
>> server.bigpond.net.au>) about '10.7MHz video demodulator', on Sat,
>> Jan 2003:
>>> I cannot say what bandwidth your R8500 has at 10.7MHz
>>> but my ICOM R7000 bandwidth is around 5-6MHz so you should be able
>>> to receive the sound and colour carriers as well.
>> It sounds suspiciously like masochism to design a 6 MHz bandwidth
>> with a centre frequency of 10.7 MHz. The asymmetry problems must be
> I suspect it's not designed there, just incidental.
> Likely, there is a roofing filter at some higher IF, and that
> to be 6MHz or so wide. Though, who knows whether that wide an IF
> is due to design limitations, or they deliberately made it that wide
> for the sake of this TV adaptor. If the latter, it seems pretty
> since it must impact on the rest of the design, and TV sets are
> good for that sort of thing. More likely, if it's deliberate, it's
> there for panadaptor type things (a visual representation of the
> signals in that 6MHz or so band segment) and the TV adaptor is again
> So the point that being tapped is at the output of the mixer that
> brings the signal down to 10.7MHz, before any filtering (or minimal
> filtering) comes into the signal path. There may be a good reason
> the overall design which makes the output point at that frequency
> rather than at the higher IF.
The 10.7MHz IF output is taken directly from the second mixer without
any filtering that I'm aware of. (ICR-7000). Frequency response
extends from 10.7MHz to roughly 16MHz. I don't know if this is
intentionaly done to be used with a TV adaptor or a panoramic adaptor.
I've found another article that covers the ICR-7000 being used for AM
Further info can be found at
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup