[UK-CONTEST] TS830 Filters

[Andy swiffin]

>>> "Ray Hills" <g3hrh at btinternet.com> wrote on 11/01/2006 09:10:12:
> For Andy, GM8OEG.  Can you tell me more about the audio filter you 
> used? (you can mail me at g3hrh at btinternet.com).  I also use a TS830.  

Hi,

I've been corresponding directly with Ray about this, but it did occur to me that there may be some on the list who might also be interested ( "big rigs" with hyper posh radios may press delete now).

My old Ts830 doesn't have the optional CW filter and although you can turn the bandwidth down to 500hz with the vbt it's still a nightmare trying to work a CW contest (or even a busy band) particularly if like me you get quickly brain limited when confronted with a pair of headphones full of competing CW sigs.

I thought an  add on Audio filter might help a bit and there are quite a few (similar) designs around, http://www.alg.demon.co.uk/radio/136/af_filter.htm is a good typical example.

In a fit of lazyness I took the easy way, though, and built mine from a kit.  Vectronics produce one (the 820K) which is pretty much identical to the design above, in the US its $20 or (predictably) £20 in the UK, available from wsplc.   With a bit of Vero and a couple of dual op amps you could probably build one for well under a fiver....... 

Variable bandwidth is achieved by simply switching out stages (ok, variable skirt really but the effect is the same) and it works very very well.

I wired mine directly into the audio line at the af gain pot on the 830.  I've been very impressed with the result, signals that are _just_ there in the midst of a crowd and totally uncopyable (by me) come out in solitary Q5 magic when the filter is switched in.

I guess most of the correspondants on this list have no need for anything as primitive as this, but there may some in your clubs with simpler or older rigs who may be interested.

Cheers
Andy
gm8oeg