[TenTec] Re: [Ten-Tec] Alas, not for me

[Joe Giacobello]

Bob, are Sherwood's data for the FT1KMPs with the 4 KHz Inrad roofing 
filter installed?

73, Joe

Bob Henderson wrote:

>----- Original Message ----- 
>From: "John Rippey" <w3uls at 3n.net>
>
>  
>
>>Finally, with the new roofing filters forthcoming from INRAD, a bunch of
>>older radios soon are going to have sterling dynamic range capabilities,
>>and you won't have to jump through hoops like the mods required on the
>>TS-870, or shell out big bucks.
>>    
>>
>snip
>  
>
>>I wonder if George's new filters will have the effect of discouraging
>>introduction of new ham rigs since the older ones are being given such
>>powerful new legs?
>>    
>>
>snip
>
>This will be an interesting one when the full story is told.  Certainly so
>far as the FT1kMP is concerned.  The roofing filter from Inrad has a 4 kHz
>b/w which makes quite a good choice for SSB but is a lot of b/w for CW.
>Interestingly, the filter requires some additional amplification to get over
>its insertion loss and I understand that Inrad have opted to include enough
>amplification to get over that loss and add a little bit more.  What price
>that extra amplification?
>
>Figures published by Rob Sherwood
>
>http://www.sherweng.com/Dayton_2004/Dynamic_Range_Data.pdf
>
>show the following dynamic range numbers at 2 kHz:-
>
>TT-Orion 1 kHz roofing    92db
>FT1k MkV        70db
>FT1k            69db
>FT1kMkV Field     60db
>
>Sherwood also states that an additional 6-7db improvement in IMD at 2 kHz is
>obtained with the Inrad 762 filter.  This puts Orions range at 2 kHz up to
>98db or better.  That's a full 28db better than the FT1k MkV and 38db better
>than the Field.
>
>That's a big gap and one that can only widen when the roofing filter mod is
>added.  The question is by how much?  As a CW man, I wonder whether the
>benefit in improved IMD at 5 kHz will outweigh the deterioration in IMD at 2
>kHz.  I have an MP but for now my roofing filter dollars will stay in my
>pocket.  Time will tell.
>
>Bob, 5B4AGN
>
>
>_______________________________________________
>TenTec mailing list
>TenTec at contesting.com
>http://lists.contesting.com/mailman/listinfo/tentec
>
>
>  
>