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Author Topic: Anyone else like a wider CW filter option?  (Read 4202 times)

Posts: 186

« Reply #15 on: February 04, 2010, 04:36:58 AM »

That's why I enjoy my IC-746pro ............ the filter options are great. I have a choice of 3 from a single button push and I can set/tailor them. I have mine set for 2.1 KHz with wide skirts for general SSB use and 1.9 KHz with tight skirts for SSB in QRM and general CW use and 400Hz with wide skirts for CW in QRM use.

It gives me the sound I like that's not too tireing for routine use and the selectivity I need for QRM conditions. But the best thing is that it's easily selectable in a couple seconds and a button push if I change my mind for what I want/need.

Posts: 60

« Reply #16 on: February 06, 2010, 05:23:44 PM »

My old SX-101A had a 500 cycle, er, hertz setting but the filters were LC not crystals so the skirts were broad.

I tended to use the 1.0 or 2.0 setting because it sounded better and I could hear more of the band.

Later I experimented with high-pass and low pass audio filters feeding a stereo amp and widely separated hi-fi speakers against the far wall.  The separation was about 15 feet.  I was about 20 feet from the wall.

I was using a Heathkit solid state stereo amp and Acoustic Research speakers.

The effect was astonishing.  I could almost "see" CW stations move across the wall as I tuned up and down the band.

They would start on one side and slowly move.

The narrowness of the filter was almost a disadvantage because I look over at the right, copy the CW station there and ignore the ones that were off to the left.

This is called the "cocktail party effect", where you can pick out people by their physical position in the room even though a dozen conversations are going at once.

For this to work, you'd need a large room.  I don't think stereo headphones can create the ambiance and 3-space sensation.

de ah6gi/4

Posts: 7718

« Reply #17 on: February 06, 2010, 08:53:10 PM »

No. 400 Hz for tuning around. 200 Hz for copying thru noise. That does it for me.

Posts: 17

« Reply #18 on: February 08, 2010, 09:26:30 PM »

I also like being able to open up the bandwidth, depending on what I'm doing with the receiver, and how crowded the band is.  If the receiver is just on for ambience I like approximately 1.2KHz.  Of course, while listening to something specific I narrow the bandwidth as required.

I do find it easier to use the maximum bandwidth consistent with the desired reception.  The IF DSP rigs with multiple filters are a joy.  I have found that positioning a manual notch just above the desired reception can help a filter with wider skirts, and is particularly useful in conjunction with the passband tuning with a slightly wider (say 500 Hz) filter.  As mentioned above, adjusting the AGC in conjunction with the RF gain can really get you in the pocket for longer ragchews with stations with good signals on a steady band (he said with a straight face).

Good stuff these current receivers.  73 Ric K5RIX

Posts: 340


« Reply #19 on: February 09, 2010, 12:52:18 PM »

I have an FT901DM which is fantastic for CW with the 2.1 SSB filter.  I use the passband tuning for narrower filtering, and for really crowded condx I use the tunable audio filter, which is really very good...almost no perceptible ringing.

I do like to hear what's going on a few kc away, so I use the widest bandwidth I can for the conditions.


Posts: 1840


« Reply #20 on: February 19, 2010, 03:16:22 PM »

I'm running a Flex radio, and if I want to "see" what's on the band I just look at the panadapter.  I usually run my filters at 25hz which gives me best SNR.  The radio will tune down to 11hz filters and you actually can tell a difference between 11 and 25 but the difference is minimal and tuning becomes extremely critical at 11hz.  The filters do not ring.  The Flex system is set up with a dual channel AGC that allows you to set the AGC threshold to the band noise so weak signals do not pump, but strong signals do not overshoot.  With this setup I can hear signals that are just a couple dB out my band noise, even if there is someone s9+ as little as 100hz away as long as they are not producing much in the way of clicks or sidebands.  

The radio uses a kind of phasing method to demodulate and I have even copied S2 signals UNDER S9 carriers directly on freq by turning on the auto notch filter and notching out the offending carrier, and then copying the phase noise generated between the CW signal and the carrier.  I've made more than one DX contact using this precise method with a tuner upper on the DX freq.  It is the best CW set up I've ever experienced.  If I want to read the mail wide band style, I can go up from 25hz to 15khz in one hz steps.  Reminds me of the Hallicrafter's S40B days, where 40M CW occupied about 3/8 of an inch on the dial.

73  W9OY

Posts: 18

« Reply #21 on: March 01, 2010, 06:14:06 PM »

When working CW on the analog satellites a wide filter is a necessity. Not all stations use full duplex doppler compensation and if you set the filters too narrow the station your working can drift right out of your filter passband. I'm running a TS-2000 and start off with the filter set to 1K and if the other guy has a nice stable signal I'll dial down to a 500 Hz filter to improve the S/N ratio.


John K2ZA

"CW from space, the final frontier..."

Posts: 179

« Reply #22 on: March 30, 2010, 12:30:07 AM »


Yes.  I set one filter to 1000 Hz for general tuning with my IC-746PRO and employ a poor man's panadaptor (my digimode waterfall) to spot signals I can't even hear.  The filter between the headphones keeps track of those I can.

If I'm seeking a clear spot for a transmit frequency, it is nice to see exactly where the neighbors are & how much elbow room exists between them.  If there's too little room for their comfort, I'll just move along to another spot. 

Or, if I hear a station I want to call, I just click that trace on the waterfall & hit the "ALIGN" hot key.  In an instant, I have that signal in the center of my pass band and I'm zero beat, too (isn't CAT great?).  If necessary, I can instantly shut out the world by choosing a narrower filter.  I have 3 adjustable choices with the IC-746PRO, and my presets are usually 500 Hz and 250 Hz in addition to the 1000 Hz general tuning filter. 

There have been times when I've set a narrow filter and tuned for stations.  For the life of me, I can't remember what prompted me to do it, but the effect was like searching for something in a dim room with one eye closed.   Smiley  73

Gary, K9ZMD/6

Posts: 113

« Reply #23 on: April 09, 2010, 07:39:54 PM »

I subscribe to the philosophy that the best filter is the one between your ears.  A bandwidth of 1 kHz works well, especially when there is a lot of qrn that would ring intolerably with 500 Hz or 200 Hz.  A bandwidth of 2 kHz also works well but I can find little additional benefit from immunity from ringing at that increased bandwidth.  I usually leave bandwidth, in a homebrew receiver, at 2 kHz unless off-frequency qrm is really bad.

Hope this info is useful.  73 de John/AD7WN
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