[1000mp] ARRL REVIEW ROOFING FILTER

[Jay Bromley]

Hi Dale,
The Inrad instructions mentions that that mod would hurt wider band modes
since the roofing filter goes out to 4K.  Like you I didn't find this to be
the case at all and was also very surprise on how well AM sounded after the
mod.  I wasn't too impress with the Mark V as a SWL rig so adding
performance was more important to me than fidelity.  I mainly use this rig
for DXing.  I am very  happy to say  that the AM fidelity is still very FB
in the Mark V Field.  After looking at the Inrad graph of the stocking
roofing filter and comparing it to the Inrad roofing filter, the mod is a
keeper.  I am pretty picky when it comes to good sound, but if I am looking
right at the Inrad graph, the new filter seems to a true 4 K filter at the
peak and around 10 K at -60.  So a very good compromise over the stock
filter which was super wide!

73 de w5jay/jay..




> 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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