[Yaesu] Filter Improvements for FT-1000D

[Ed Senior]

Hi Joe - 

Thank you very much for your comments!  
I have interleaved a few follow-ups, below... 

73, Ed, W6LOL


----- Original Message ----- 
From: "Joe Subich, K4IK" <k4ik at arrl.net>
To: "'Ed Senior'" <eseniors at earthlink.net>; <yaesu at mailman.qth.net>
Sent: Sunday, May 08, 2005 11:31 AM
Subject: RE: [Yaesu] Filter Improvements for FT-1000D


> 
> Ed, 
> 
> > >
> > > 2800 Hz Inrad instead of the standard 2400 Hz Yaesu
> > > 2100 Hz Inrad as optional SSB
> > 
> > I take it you prefer leaning a bit more towards "high
> > fidelity" audio, vs. maximizing selectivity.
> 
> Yes, Hans likes the higher fidelity audio on SSB <G>.  Based 
> on their part number, each of the Yaesu filters (8.215 MHz and 
> 455 KHz) are actually 2600 Hz wide at the -6 dB points.  When 
> cascaded, they yield 2400 Hz overall at the -6 dB points. 
> 
That all makes sense, and I don't see much wrong with it if they 
are good filters.  But specifying BW at the 6dB points is kind of 
nonstandard, and I can see why some might want a little more BW. 

> > > 400/500 Hz Inrad as optional CW
> > 
> > I assume you feel the Inrad 400 outperforms the Yaesu
> > 500; but another recent poster seems disappointed to
> > find little difference.
> 
> This is an "apples to oranges" thing.  The original FT-1000 
> third IF filter option was a crystal filter.  Yaesu's current 
> offering for the MP/MKV/Field is a Collins mechanical filter - 
> it is exceedingly wide (look at INRAD's curves as their Collins 
> filter is identical to Yaesu's).  The INRAD 400 or 500 Hz crystal 
> filter has vastly superior skirt selectivity and I doubt that you 
> will see a lot of difference (about 50 Hz based on the curves on 
> the INRAD web site) between their 400 and 500 Hz units. 
> 
> I am replacing the 500 Hz Collins filter in the subreceiver of 
> my Mark V with an INRAD crystal filter because the Collins 
> filter is so sloppy and I will probably replace the 600 Hz 
> six pole (crystal) CW filter in the subreceiver of my FT-1000D 
> for the same reason.  
> 
I rarely use CW, and would never use CW in a contest; so the 
performance of the standard 1000D filter seems fine to me.  
The only reason why I might want to change it would be if 
I wanted a substantially wider BW, per Hans' idea.  

> > > Sub Rx:
> > >
> > > 2800 Hz Inrad (wire-in) instead of the standard 2400 Hz Murata
> > >
> > Is "higher fidelity audio again the concern?
> 
> No ... here the stock 3rd IF filter is a Murata ceramic filter.  
> Its skirts are quite sloppy (maybe four poles).  The wire-in 
> crystal filter does the same job as replacing the Murata ceramic 
> filter in the main receiver as part of the "D" package.   
> 
> I would use the INRAD 2100 Hz filter for this purpose.   
> 
Even though I have only worked split about a half dozen times, 
I can see where it would be nice to improve the Sub Rx.  

> BTW, the INRAD web site indicates the FT-1000D roofing filter 
> is available (delivery at Dayton).  Based on the results in my 
> Mark V, I would make a roofing filter the first filter addition 
> to an FT-1000/FT-1000D.  
> 
Now this sounds interesting.  But would this be a hack-type 
modification, or does the 1000D have an available "slot" for 
a roofing filter?  

> My personal recommendations are: 
> 
> FT-1000D: 
> ----------
> 1) INRAD roofing filter 

See question above. 

> 2) INRAD 400 Hz CW filter for the sub receiver 

If one replaced the Main Rx 500 Hz filter with one of these, 
could the standard filter from the Main be trickled down to 
this spot in the Sub?  

Also, if one wanted to minimize "unauthorized" mod's, couldn't 
one just add another standard 500 Hz filter to the (presumably open) 
"slot" in the Sub?  

> 3) replace the Murata ceramic filter in the sub-receiver 
>    with an INRAD 702 

That would be nice.  Would another of the original Yaesu 
XTAL filters (same as the Main) be another option? 

> 4) add the optional 250 Hz 3rd IF filter if necessary.

Would the benefit of this simply be that selecting a 250 BW 
would also give that BW in the Sub, instead of the Sub 
just staying at 400/500 Hz?    
>  
> FT-1000: 
> ---------
> 1) INRAD roofing filter 
> 2) INRAD 400 Hz CW filter for the sub receiver 
> 3) Replace the ceramic filter (SSB) in the 3rd IF 
>    with an INRAD 715C (2800 Hz Crystal filter) or 
>    the Yaesu XF-C if you can find it. 
> 4) Add the INRAD 400 or 500 HZ crystal filter to 
>    the 3rd IF 
> 5) replace the Murata ceramic filter in the sub-receiver 
>    with an INRAD 702 
> 6) add INRAD 1800 Hz and/or 250 Hz filter pairs depending 
>    on your own operating habits. 
> 
> 73, 
> 
>    ... Joe, K4IK 
>  
> 
> 
>