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G0FTD > FT817 31.01.07 01:34l 45 Lines 1650 Bytes #999 (0) @ WW
BID : 080266029PZT
Read: GUEST DL1RX DH1NHM VE7HFY DG4IAK
Subj: FT817 trick (CW)/Audio filters
Path: DB0FHN<DB0FOR<DB0SIF<DB0ROF<DB0ACH<DB0ACC<DB0EA<DB0RES<DK0WUE<CE8FGC<
VK6HGR<ZL2BAU<GB7MAX<GB7PZT
Sent: 070130/2327Z @:GB7PZT.#24.GBR.EU [Kidderminster] #:26608 XSERV410h
Date: Tue, 30 Jan 2007 23:27:03 +0000
From: g0ftd@gb7pzt.#24.gbr.eu (Andy)
To: ft817@ww
Subject: FT817 trick (CW)/Audio filters
I originally made my passive audio filter as a companion for my FT817,
to see if it would be a practical alternative to purchasing the Collins 500Hz
xtal filter as well as a practical exercise in audio filtering.
I've sent the filter details, no need to yet again).
Well now I've started to use the filter (made month ago) with the FT817
I've found a useful trick to use.
Firstly the audio filter really is razor sharp - too sharp really.
40Hz bandwidth is a bit overkill, but it really does allow me to kill
the QRM and read cw signals that without the filtering are simply lost
in the noise. The big problem is tuning the darn signals in.
You only have to breath on the VFO dial and it's out the passband.
There no giving the VFO a quick twiddle over the band !
So the trick is this:
a)Set the FT817 menu for a 750Hz sidetone. This is close enough to the 730Hz
centre freq of the audio filter.
b)Tune in the CW signal whilst holding in the HOME key. The HOME key
continues to emit a 750Hz tone. Adjust the wanted CW signal to match
the 750Hz tone. The CW beat note is now almost matching the audio filter
and can easily be tuned by the required 20Hz to match the audio filter.
If this all sounds a bit odd for some readers,(not using ultra narrow filters)
I can assure you it makes life a lot easier otherwise safecracker's fingers
extraordinaire would be essential.
The FT817 menu can of course be set to other beat note freqs to match any
other filtering and for netting.
- Andy -
G0FTD @ GB7PZT
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