From: John Woodgate
Subject: Re: Improving a Grid Dip Meter
Date: Tue, 24 Dec 2002 21:12:00 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Tue, 24 Dec 2002 21:13:39 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Paul Burridge
wrote (in ) about 'Improving a Grid Dip Meter', on Tue, 24 Dec 2002:
>I have a fairly oldish (say 1970) GDM which can also function
>(theoretically at any rate) as a relative field-strength meter.
>However, it's pretty 'deaf' so the later functionality of it is
>impaired. The degree of dip when sussing out plain tuned-circuits is
>also pretty lousy. Taking the back off shows the amplifying section of
>this unit to consist of two elderly-looking tin-cased 2SB422
>transistors which for some reason are soldered in circuit with full
>inch-and-a-half leads. Seems a bit odd given the claimed top-end
>frequency response of 280Mhz. Anyway, what, in the view of the panel,
>are the most suitable up-to-date devices to replace 'em with in order
>to improve sensitivity?
Changing the transistors is most unlikely to produce any improvement,
assuming they are not faulty. To take advantage of modern devices, a
total re-design would be required.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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