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eHam Forums => Elmers => Topic started by: RADIOPATEL on November 01, 2017, 12:45:39 AM



Title: Filter for FT 817
Post by: RADIOPATEL on November 01, 2017, 12:45:39 AM
Dear Experts
I have FT817 qrp radio. I wish to work CW and digital modes. Can I use 300Hz filter for digital as well as CW. I tried however I did not found precise answer at other forums hence I request you all Experts to help me select the filter. 500 Hz I feel wide for CW work.
Tnx in advance.
VU2DCI - Dinesh Patel Mumbai India.


Title: RE: Filter for FT 817
Post by: G8YMW on November 01, 2017, 05:31:03 AM
Hi Dinesh,
Should work well


Title: RE: Filter for FT 817
Post by: AC2EU on November 01, 2017, 06:21:54 AM
As long as your digital mode BW doesn't exceed 300Hz it will work.


Title: RE: Filter for FT 817
Post by: W9IQ on November 01, 2017, 07:16:49 AM
Be aware that for some of the more popular digital modes, the software is designed to work with a 2.5 kHz or so bandwidth even though the modulation method uses much less. The new FT-8 mode is an example of this. The software performs digital signal processing to narrow the bandwidth as needed during receive. The wider bandwidth allows the software to find other signals in the passband without needing to "tune around".

You will actually loose some features of the software if you attempt to use it with a narrower filter. Your SNR reporting to the other station will also be off by 9 dB or more.

- Glenn W9IQ


Title: RE: Filter for FT 817
Post by: RADIOPATEL on November 02, 2017, 06:36:19 AM
Thanks to all three hams.

Dear OM Glenn, Shall I use 300Hz filter for CW and by pass the same for digital modes? Is there a need of wider filter? My radio is FT 817 QRP radio.

73

TNX
VU2DCI - Dinesh Patel



Title: RE: Filter for FT 817
Post by: W9IQ on November 03, 2017, 05:06:38 AM
Dinesh,

Your proposal.should work just fine. I don't think a wide filter is warranted.

- Glenn.W9IQ


Title: RE: Filter for FT 817
Post by: KM4DYX on November 03, 2017, 05:06:26 PM
Thanks to all three hams.

Dear OM Glenn, Shall I use 300Hz filter for CW and by pass the same for digital modes? Is there a need of wider filter? My radio is FT 817 QRP radio.

73

TNX
VU2DCI - Dinesh Patel

I'm an 817 operator as well. Digital modes work just fine without a filter. My CW filter is 500Hz; your 300Hz will work great.

73,
Al


Title: RE: Filter for FT 817
Post by: K0UA on November 03, 2017, 05:13:48 PM
Your narrow filter will work well for some modes but not for others.  Example for PSK31 it should work well, but keep in mind where its center frequency is as you try to work a station and you have it on wide, you need to figure out where that station is located and if you click in the 300hz filter where will that station be on the waterfall, and will they be chopped off.  For FT8, JT65 and MSK144 you will want to use your widest filter all the time.  Some other modes will be too wide for your narrow filter and will be chopped off even if they are centered in the passband of your filter.  Example an 500hz Olivia signal.


Title: RE: Filter for FT 817
Post by: KC1BMD on November 08, 2017, 07:21:57 AM
I tried it but don't bother using the CW filter with PSK31 for some reasons cited above. I chose the 500Hz CW filter because on reading about it, some thought the 300Hz filter too tight, but YMMV.