[1000mp] Real S9

[Chuck Lewis]

Gee, Pete, I'm not trying to start a war here, but it seems to me that the 
gain distribution (affected by the I/F gain setting) should be set for max. 
S/N, not diddled with as a means to correct an S-meter mal-calibration. On 
the other hand, suggestions have been made that (after any Inrad mods, etc.) 
the I/F gain be adjusted until the main RCVR S-meter indicates the same as 
the Sub-RCVR reading. That would seem to be a way of returning the overall 
I/F gain to its factory setting. This seems fine as long as one assumes that 
the sub-RCVR setting is consistent with the best main RCVR S/N ratio: a bad 
assumption, IMHO.

Why wouldn't it make more sense to (somehow) establish the best S/N ratio by 
adjusting the I/F gain and THEN use the 50 uV standard to set the S-meter 
sensitivity? I've played a little with the I/F menu setting using barely 
readable sigs to reach a (subjective) optimal setting. That turned out to be 
fairly consistent with Inrad's suggested compensation when installing their 
I/F mod kit. My S-meter seems stingy, too, but it seems a bad trade to give 
up weak signal performance (and lose the "hiss reduction" we paid for in the 
Inrad kit) just to get the S-meter right when there's probably a dedicated 
S-meter sensitivity adjustment somewhere.

What am I missing here?

73,
Chuck, N4NM
(Who's wishing he had one of those VG-1 kits, too :>)



----- Original Message ----- 
From: "Pete Smith" <pete.n4zr at gmail.com>
To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
Sent: Sunday, March 25, 2007 2:58 PM
Subject: [1000mp] Real S9


>I just finished building the Elecraft XG-1 signal generator.
>
> So why am I talking about it here?  Because It puts out a calibrated 50 uv 
> on 7040.  After I built it, the first radio I hooked it to was my TS-930. 
> S9 right on the button.  Then I connected it to my Mark 5.  S6!
>
> I had thought for a long time that the Mk 5 sounded "dead" compared with 
> the 930, but put it down to DSP, etc.
> Not long after I got the MK5, I put in the Inrad IF mod, and then a couple 
> of years later I substituted the roofing filter.  The radio also has 
> cascaded 400 Hz Inrad CW filters.  In the course of doing all that, I 
> guess I had turned the IF gain down too far - anyway, using the XG-1, I 
> was able to reset it to ~S9 at 50 uV - certainly sounds like the band is 
> more open!
>
> I expect the VG-1 is going to prove very useful, anytime I want to check 
> the performance of my antenna switching or bandpass filtering - and for 
> $40, I can't imagine a cheaper way to do that.
>
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