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Title: Nuvistaplug Post by: KE5YTV on November 22, 2009, 03:14:14 PM Hi Fellows. I'd like to do the Nuvistaplug upgrade on my SP-600. Can anyone furnish a source or info on building one. Thanks and 73's, Mike Bracey, KE5YTV
Title: Re: Nuvistaplug Post by: Pete, WA2CWA on November 22, 2009, 06:00:32 PM Go here:
http://www.mines.uidaho.edu/~glowbugs/SP600upgrd.pdf Title: Re: Nuvistaplug Post by: WBear2GCR on November 22, 2009, 11:04:41 PM Innertesting! Should be fairly simple to constuct! Applicable to any receiver!! Seems like the second stage is "grounded grid" - which seems odd to me. I'm wondering why they didn't use a cascode arrangement instead, or a true cascade if more gain was needed to be made up... maybe their arrangement keeps the noise figure lower... _-_- Title: Re: Nuvistaplug Post by: K4TLJ on November 23, 2009, 05:14:20 AM A 6GU5 can be used also. Retains or increases gain and drops the noise much the same. Socket rewiring is necessary. The screen dropping resistor usually is around 680K to 1 meg! Tie pins 2 and 7 together at the socket. The suppressor grid is usually directly grounded so must be lifted and tied to the cathode.
AGC may need to be reduced by a voltage divider. Title: Re: Nuvistaplug Post by: KE5YTV on November 23, 2009, 08:17:21 AM Thanks for your help and thoughts on this. 73's, Mike AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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