[1000mp] ARRL REVIEW ROOFING FILTER

[Mike Schatzberg]

Hello Yaesu Fans:

It would be interesting to note, whether they left the factory default IF
gain set as Yaesu provided the radio, or whether they lowered the gain
before making the measurements.

I would also assume from the numbers, only an assumption of course, that the
noise blanker modification had not been done to this radio, based upon the
reported results.

I found that a 50 microvolt signal on 10 meters was S9 on the Mark V meter
with the preamp on and tuned, prior to the mod.  After the mod, 50
microvolts was S9 plus 15 DB.  Lowering the factory default number in menu
9-1 by three numbers, returned the reading to S9.  I finally decided upon 2
number reductions as being the best signal to noise adjustment while using
the digital product detector in the Mark V.

I would think if this adjustment were made, the noise floor might well be
lowered by 10 DB, rather than the 7 DB stated in this article.

I have recommended this change to several colleagues who have also installed
the mod, all report improved results with this adjustment, which is contrary
to the Inrad instructions.  Inrad states you should increase the IF gain if
you reduced your setting for their earlier IF amp mod, and return the
setting to the factory default..  I also note that in the RSGB article,
recently published, that they too have recommended adjusting the IF gain
downward from 2 to 3 numbers from the factory setting.

I would be interested to hear anything further about this as I do not have
any access to the ARRL article.

73 and Happy Dxing,

Mike Schatzberg
WB2AJI
----- Original Message ----- 
From: "D. J." <dalej2 at mac.com>
To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
Sent: Thursday, December 23, 2004 1:44 PM
Subject: Re: [1000mp] ARRL REVIEW ROOFING FILTER


> Dirk,
>
> Here are some numbers:
>
> MKV noise floor before the INRAD roofing -123 and after -130
>
> Blocking at 20 khz spacing before 130 db   after 146 db
> 5 khz spacing before 105 db after 130 db
> 1 khz spacing before 104 db after 106 db
>
> IMD dynamic range 20 khz spacing before 88 db after 93
> 2 khz spacing before 69 after 79
> On Dec 23, 2004, at 10:51, ON4ADZ wrote:
>
> The report says "improvement is notable".
>
>   I have it installed in my own MKV and It's a noticeable improvement
> without affecting the normal SSB audio.  AM even sounds ok to my old
> ears.  I highly recommend it.
>
> 73
> Dale, K9VUJ
>
>
> > Dear
> >
> > I am intrested in a summary of this arrl only member review.
> >
> >
> > With thanks,
> >
> > ON4ADZ
> > dirk
> > on4adz at skynet.be
> >
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