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Author Topic: Best CW Filter for FT897D?  (Read 4454 times)
G4JJP
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« on: March 17, 2011, 01:53:10 AM »

Recently returned to CW after 40 years(!).  Got myself an FT897D, and it has a DSP filter that makes morse code sound like it's in a train tunnel, and I'm amazed at how close some people transmit to each other! Anyone using an FT897D? What's the best CW filter to fit to separate these signals without trying to read morse in an echo chamber?

G4JJP
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KC9TNH
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Posts: 304




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« Reply #1 on: March 17, 2011, 10:40:15 AM »

I would try these folks. Their knowledgeable service is first-class. They've probably done their best service to QRP with a cheaper-than-Yaesu 500Hz CW filter for the 817 but do all kinds of stuff.
Ralph & Co are good people.
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73
Wes -KC9TNH
"Don't get treed by a chihuahua." - Pete
KD8DEY
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Posts: 352




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« Reply #2 on: March 17, 2011, 02:18:03 PM »

looking online at reviews etc Inrad seems to have the most highly regarded filters and they have CW filters for that radio in 300 & 500hz flavors.

http://www.inrad.net/home.php?cat=126
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STAYVERTICAL
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Posts: 875




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« Reply #3 on: March 18, 2011, 06:01:54 AM »

I have an FT897D and fitted the 500hz Yaesu filter (which is actually a Collins mechanical filter).
I chose the 500hz filter over the 300hz because 500hz is a commonly used digital modes bandwidth and it is not far from 300hz in any case.
Very easy to install (just take off the top cover and plug in the filter onto pins already fitted - no soldering required).
The FT897D has two places for optional filters, so if you really want, you could fit both a 300hz and 500hz filter if desired.
I have the second slot populated with a 2.3khz Yaesu mechanical filter, but would not say it is really worth fitting.
A second filter of 300hz would be my choice if I had to do it over.

I use the DSP setting "DBF" which gives a CW peaking filter and personally find it very useful and easy on the ears, but that may just be my preference.
Using the 500hz filter and the DBF DSP setting makes for a pretty good CW environment.

73s
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VE3WMB
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Posts: 289




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« Reply #4 on: March 19, 2011, 07:34:29 AM »

I agree with STAYVERTICAL. The 500 hz mechanical filter is the best place to start (either the Yaesu (Collins) or INRAD). If you go with the 300hz filter you will likely find that it is a bit too narrow to have engaged while tuning around.  You can always add the 300 hz filter as the second filter later on if you feel that you really need it.

Likely part of your dissatisfaction with just the audio DSP filtering in the FT897D is that even though
the DSP audio filtering may filter out the audio of of interfering stations, those stations are still within the passband of your 2.8 KHZ IF filter and thus they will have an impact on the AGC, causing it to pump. No doubt you have
experienced this. Usually you will hear a bit of a thump and the station you are trying to copy drops out because
the rig is responding to the overload caused by the stronger interfering signal, thus drastically reducing the
receiver gain.

Personally I find that the FT897D with the 500hz Collins filter + the DBF feature of the
built-in DSP audio filter works pretty well for CW operation.  If you find that the DSP filtering is too narrow for
your liking I believe that the bandwidth can be varied by one of the internal menu settings so you might want to
experiment with this once you have a narrower IF filter installed.

Best of luck

Michael VE3WMB / VA2NB

I have an FT897D and fitted the 500hz Yaesu filter (which is actually a Collins mechanical filter).
I chose the 500hz filter over the 300hz because 500hz is a commonly used digital modes bandwidth and it is not far from 300hz in any case.
Very easy to install (just take off the top cover and plug in the filter onto pins already fitted - no soldering required).
The FT897D has two places for optional filters, so if you really want, you could fit both a 300hz and 500hz filter if desired.
I have the second slot populated with a 2.3khz Yaesu mechanical filter, but would not say it is really worth fitting.
A second filter of 300hz would be my choice if I had to do it over.

I use the DSP setting "DBF" which gives a CW peaking filter and personally find it very useful and easy on the ears, but that may just be my preference.
Using the 500hz filter and the DBF DSP setting makes for a pretty good CW environment.

73s
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AA5TB
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Posts: 81


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« Reply #5 on: March 25, 2011, 01:15:11 PM »

I agree with Michael but I use the 300 Hz mechanical filter from W4RT with my FT-897D and I'm very satisfied with it, not that it's a better choice.  The 500 Hz filter should be fine too.  It's really a personal preference which one to use. 

In regards to using the DSP audio filter I find that if you turn the RF Gain back to the point where the S-meter shows about the same level as an offending station and then turn up the audio to compensate that the DSP filter works almost as well as the mechanical filter.  Strong out of pass band signals won't "pump" the AGC then.  It tend to always keep the RF Gain turned back anyway as it restores the dynamic range of the signals I'm receiving and gives my brain that much more data to help discriminate different signals and is less fatiguing.  Again this is just a personal preference. 

The mechanical filter has just enough group delay through it that the AGC doesn't respond instantly when listening through it and there tends to be a mild pop at the beginning of the CW notes if the RF Gain isn't turned back just a bit, usually not enough to be bothersome.  The DSP filters doesn't experience this effect but the filter skirts aren't as good as the mechanical filter.

73,
Steve - AA5TB

I agree with STAYVERTICAL. The 500 hz mechanical filter is the best place to start (either the Yaesu (Collins) or INRAD). If you go with the 300hz filter you will likely find that it is a bit too narrow to have engaged while tuning around.  You can always add the 300 hz filter as the second filter later on if you feel that you really need it.

Likely part of your dissatisfaction with just the audio DSP filtering in the FT897D is that even though
the DSP audio filtering may filter out the audio of of interfering stations, those stations are still within the passband of your 2.8 KHZ IF filter and thus they will have an impact on the AGC, causing it to pump. No doubt you have
experienced this. Usually you will hear a bit of a thump and the station you are trying to copy drops out because
the rig is responding to the overload caused by the stronger interfering signal, thus drastically reducing the
receiver gain.

Personally I find that the FT897D with the 500hz Collins filter + the DBF feature of the
built-in DSP audio filter works pretty well for CW operation.  If you find that the DSP filtering is too narrow for
your liking I believe that the bandwidth can be varied by one of the internal menu settings so you might want to
experiment with this once you have a narrower IF filter installed.

Best of luck

Michael VE3WMB / VA2NB

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N0EQ
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Posts: 74


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« Reply #6 on: April 25, 2011, 02:34:39 PM »

My experience with an 857, very similar to an 897...

I have the 2.3 SSB filter and the 500 CW filters installed.
I ALWAYS find myself reverting to the stock CFIL filter
that comes with the Yaesu.

DBF and DNR audio filters bring most all of the band pass
to where I want it. If then, there's another REALLY close
station, I simply IF shift it a bit.

AF up, RF down/adjust as needed.

Both aftermarket filters were a waste of money for me.


Craig 'Lumpy' Lemke

www.n0eq.com
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W8JX
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Posts: 6143




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« Reply #7 on: April 25, 2011, 04:02:01 PM »

I cannot speak to quality of filters for 857 and 897 but I have long used at least a 500hz rock filter even before there was AF or IF DSP. Can make a big difference at times. Hard core CW user use a 270hz or so filter. I like 500 because it does double duty as a wide digi filter that works with Domino and RTTY too
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