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TADD-1 ECO (Was: Re: [time-freq] RE: time-freq Digest, Vol

Christopher Hoover ch at murgatroid.com
Sun Sep 10 02:22:11 UTC 2006


On Sat, 09 Sep 2006 11:01:51 -0400, John Ackermann N8UR <jra at febo.com>
wrote:
> OK, I made the following changes:
> 
> R4 changed from 10k to 1k
> 
> R6 removed
> 
> R1 and R8 both changed from 15k to 47k
> 
> and it made a dramatic difference.

I made this change on two boards.  I can confirm that it works quite
well, John.

I also hacked a third board to use the inverting configuration that I
described in a previous message.  That works well, too.   You can make
the existing layout work decently enough for this config if you pull C8
and use the existing R1/R8 divider alone for IC1's non-inverting input.
Then pull R14 and R15 and drop in the dc block cap across the R4/R6/C8
node and the R13/R14/R15 node.  Adjust R4 as needed.

I'm running +7 or +8 dBm now on my outputs now, but I can get more.  My
primary TADD-1 is driven by my HP Z3801A and its outputs go to several
instruments in the same rack, but one output goes to the next rack where
it drives a pair of TADD-1's.  Those TADD-1's drive a bunch of
instruments in that rack.

The whole deal is working happily now.

Cheers,
-ch





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