VKCW.NET

Well after many, many years of not worrying about narrow filters I'm now converted. I never used to believe in putting the extra filtering available for transceivers but after finally chasing up a narrow CW filter for the FT1000MP I would never ever not think about the extra filtering. This evening I heard stations that you could never hear without one. I have now also placed one in the FT857D as well.
So happy days of CW now with lots less QRM and QRN.

73 & 77 de Michael VK2CCW

having never had the luxury of digital filtering,
most of my gear has had only mechanical filtering.

with the current rig, it was tricky to first decide which filter to use,
and then even tricker to get it.
the CWn does get used a fair bit, too - even if it sounds like a drain pipe ..
it's also a 500hz filter, & not the 2k version.

I had a FT-817 (wish I hadn't sold it) with the mechanical 500Hz filter. It was great. Made a huge difference to the rx performance. I think the 857 circuitry is similar to the 817??

I had the current rig TS-480 for two years before I purchased a filter. And yes now that I have them I would never go back.
I have 500Hz and 270Hz filters installed. No AGC pumping with close in signals.

73, David VK3GDM

Yes narrow filters you can beat them, after installing it I both the FT857D and FT1000MP would never go back as these chop the crap out of QRM/QRN.

73 & 77 de Michael VK2CCW

Interesting comments all. My own experience is that on the HW-8 I had (QRP heathkit VFO 80/40/20/15m if I remember correctly) and 3W output I think, it had a sort of audio filter where the CW would come right up loud when at the right pitch. Amazing and so sad I lost that in ST2. In my IC-735 from the start I had a narrow 250Hz filter, and used it often, though as Peter VK6IS pointed out the howling effect isn't very nice to listen to. Now I don't have a narrow filter, and as also pointed out, the mechanical filters are not always easy to FIND let alone they're usually rather expensive, but I hope to do so, I've been lucky enough to find one but it's in a radio with a gentleman who is too ill to remove it, and he's in another state so I can't get there to help. I know it'll make a big difference, as Michael pointed out it can also down QRM/QRN but most of the time I'd probably have it off, so I can hear off frequency calls, and use my own natural ear filters, and avoid the drain pipe effect. It can also be a difficult choise in many rigs in which filter to choose as you can only have one: 500Hz or 250Hz. 500Hz will have less drain pipe, but obviously be wider. Maybe 350Hz would be a good compromise if it were available. Or just as narrow as possible without the howling drain pipe. I've been off-air for so long that I would think DSP has become more common place and perhaps an external DSP or even an audio filter would be possible, and I may look into those possibilities. Any thoughts or exerience?

I use an old Kenwood without the CW filter.
I recently made an audio filter. A copy of a Hi-Per-Mite. It worked well and didn't 'ring'. It's back in the box with all my other homebrew.
I've got a Drake 2B as a back up receiver. It has a 500Hz passband option. It very good as you leave the tuning alone and move the passband frequency.

Peter
VK3BMG

The big advantage with narrow IF filters that are operating in the IF chain prior to the AGC, is that close in signals, out side the IF narrow filter passband, don't pull on the AGC and reduce the receiver gain.

This is the problem with audio filters operating in the audio chain after the IF. When you are trying to listen to a weak signal and have a strong unwanted signal inside the IF passband, the strong signal pulls the AGC and reduces receiver sensitivity and can mask out the weak wanted signal. AGC pumping..

So on a busy band a narrow IF filter is very handy.

I usually tune around with the wide filter and then switch to the 500Hz filter in QSO. Bring in the 270Hz filter if there's an unwanted close by.

I did use an adjustable audio filter on my previous rig (IC-718) which had very harsh/noisy audio chain. It also had a 500Hz IF optional filter, but needed the baseband filtering to clean it up.