[TenTec] filters

Thu, 22 Apr 1999 01:43:57 +0100 (BST)

You CAN work CW effectively with only the stock TT SSB filters, but
under crowded band conditions it takes a fair bit of practice to do
it. Its much more comfortable to listen to a narrower bandwidth.

With an Omni-V there is only one spare slot at 9 mHz. For casual CW
I'd leave it empty and just fit a 500 Hz filter (TT or INRAD) in the
second IF at 6.3 mHz. The stock 9 mHz SSB filter is still in line and
limits the amount of crud reaching the 6.3 mHz IF strip. 

Once you are hooked on CW then get the 9 mHz 500 Hz filter (TT or
INRAD) as well, and fit that in the "narrow" slot. Two 500 Hz filters
in series (with the stock SSB filter ahead of them) do a good job
without being too narrow for everyday use. I use this combo all the
time; its very comfortable and non-critical for tuning. I rarely use
the TT 250 Hz filter, which I also have in the second IF. 

I have a 1.8 kHz SSB filter in the second IF as well. I find it is
occasionally useful, but I could live without it. I would be
completely lost without the two 500 Hz filters for CW though, because
I spend a lot of my time on 30/40m in the evenings, nights and early
mornings. I live next door to the European QRM machine and those 500
Hz TT filters in my OMNI-V have enabled me to copy stuff that others
were plainly struggling with. 

So whats different about the INRAD filters ?? 

Summarising what the data sheets and other users say, it seems that
they may well be built to tighter tolerances and therefore exhibit
better shape factors (steeper sides to the passband) and lower
insertion loss. If that is a correct assessment - and I do not have
any INRAD filters (yet), they will do a very good job indeed, but 
the bottom line is that only you can decide what you need, and how
much you can spend. 

Of course, it will always be a fact that none of these (expensive)
gizmos is worth much if the essential station accessory (the one
normally installed between the operator's ears) is not actually able
to tell the difference, or simply does not care. For that reason I
always suggest that anyone thinking of buying accessory filters
should first figure out exactly WHY. Then find someone who has the
same or even similar bandwidth filters and have a good listen, to make
sure that you are comfortable with them. 

As an example of what happens if you do not try to make a rational
assessment of what you really need, a radio club not too far from here
bought an OMNI-V. A solitary 250 Hz filter was also bought, because
every phone man knows that is the kind of filter CW men use for
contests. But no-one seems to have asked the CW men what they wanted
and surprise surprise, no-one liked using that OMNI-V on CW. Its
a nice radio; I tried it here and it sounded better than mine !! But I
could not live with just that one 250 Hz filter for CW. A bit
of thought and some planning would have avoided this situation. I
believe the club now uses a rice box as main rig ... what a waste.

John G3JAG  FISTS 6036

On 21-Apr-99 Joe L Blackwell wrote:
> 
> de Joe, AA4NN
> 
> About filters, they are wonderful and whether InRad or TT,
> they do the job.  If you don't work CW much, then you are
> a casual user of that mode and you don't need a 250Hz filter!
> Are you gonna rag chew with a guy who is down in the mud?
> Not likely.  If you are looking for CW DX, you may need filters.
> 
> But, with a 500Hz filter, don't forget you have Pass Band Tuning
> and when you get to be friends with that, you are really on to
> some good listening.
> 
> 73,
> Joe Blackwell, AA4NN
> This shack is all TenTec gear & CW only.
> 
> --
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----------------------------------
E-Mail: patents@dx0man.prestel.co.uk
Date: 22-Apr-99
Time: 00:30:54

Without CW its just CB ...
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