K2- setting the filters
Locked
 
|
I have been operating my K2 as a CW only radio for a few months and have now
just added the KSB2 SSB board. When I only had CW, I set the filter widths and BFO settings as per the defaults advised and was very happy with it. However, since setting the default values suggested in the KSB2 book, I've discovered a few unanswered issues. Q1, Do I have to set FL1 to OP1? I was under the impression I had to. But a friend has set his FL1 to 2.4KHz. I know this is the filter that is used to transmit. Is it OK to narrow it down? Is there any benefit? Q2, Why does the book also say FL2 should be set to OP1 on SSB? Is this a typo? Q3, I have now set the filters using spectrogram. EVERYONE should do this, it is so easy and makes a huge difference. And the program is free! Do it !!!! I found that the default BFO values in the KSB2 book had CW and USB pretty much perfect, but LSB was way off (3 or 400Hz). Retuning with spectrogram has cured that and it sounds great on LSB now. Is it normal to be so far off? Q4, The filter widths are actually much wider than that set on the K2 display. ie 2KHz filter is actually about 3KHz wide. To get the same "sound" as my other HF rigs I am having to set the filter widths much narrower than expected. ie set the display to 1.2KHz width to get an actual 1.8KHz width trace on spectrogram. Is this normal? Can this be adjusted? Am I worrying about nothing? :o) Overall i am very happy with the recievers performance. The K2 has taken over as main radio, pushing japanese sets aside. But if anyone could advise on the above, that would aid my learing process. Thats one of the reasons why i bought it :o) Thanks all 73 Jack VK2CJC / MM0AXL Fists #9666 - CW QRP Club #753 - Elecraft K2 #6404 Mid North Coast Amateur Radio Group www.mncarg.org _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
On May 2, 2008, at 2:12 PM, Jack wrote:
> Q4, The filter widths are actually much wider than that set on the > K2 display. ie 2KHz filter is actually about 3KHz wide. To get the > same "sound" as my other HF rigs I am having to set the filter > widths much narrower than expected. ie set the display to 1.2KHz > width to get an actual 1.8KHz width trace on spectrogram. Is this > normal? Can this be adjusted? Am I worrying about nothing? :o) Interesting. On our K2 the reported filter width was narrower than reported by the K2. I set the 3dB points using an audio spectrum analyzer and found that using a setting of almost 1KHz to get a 500Hz- wide filter. No problem changing widths to anything I want but it seems that the reported widths and actual widths vary widely. The only way to know for sure is to sweep the filter or dump in noise and analyze with the audio spec-A. BTW, for people using Macs, you can do the same filter setup using CocoaModem's spec-A display. > Overall i am very happy with the recievers performance. The K2 has > taken over as main radio, pushing japanese sets aside. Same here. The IC-706 has been removed from the shack at school and has been replaced by the K2 and a cheap 2M mobile FM rig. > > But if anyone could advise on the above, that would aid my learing > process. Thats one of the reasons why i bought it :o) I would really like to hear why the actual filter width varies so widely from what the radio reports too. Brian Lloyd Granite Bay Montessori School 9330 Sierra College Bl brian AT gbmontessori DOT com Roseville, CA 95661 +1.916.367.2131 (voice) +1.791.912.8170 (fax) PGP key ID: 12095C52A32A1B6C PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Jack-123
On May 2, 2008, at 2:12 PM, Jack wrote:
> Q4, The filter widths are actually much wider than that set on the > K2 display. ie 2KHz filter is actually about 3KHz wide. To get the > same "sound" as my other HF rigs I am having to set the filter > widths much narrower than expected. ie set the display to 1.2KHz > width to get an actual 1.8KHz width trace on spectrogram. Is this > normal? Can this be adjusted? Am I worrying about nothing? :o) Interesting. On our K2 the reported filter width was narrower than reported by the K2. I set the 3dB points using an audio spectrum analyzer and found that using a setting of almost 1KHz to get a 500Hz- wide filter. No problem changing widths to anything I want but it seems that the reported widths and actual widths vary widely. The only way to know for sure is to sweep the filter or dump in noise and analyze with the audio spec-A. BTW, for people using Macs, you can do the same filter setup using CocoaModem's spec-A display. > Overall i am very happy with the recievers performance. The K2 has > taken over as main radio, pushing japanese sets aside. Same here. The IC-706 has been removed from the shack at school and has been replaced by the K2 and a cheap 2M > > But if anyone could advise on the above, that would aid my learing > process. Thats one of the reasons why i bought it :o) I would really like to hear why the actual filter width varies so widely from what the radio reports too. Brian Lloyd Granite Bay Montessori School 9330 Sierra College Bl brian AT gbmontessori DOT com Roseville, CA 95661 +1.916.367.2131 (voice) +1.791.912.8170 (fax) PGP key ID: 12095C52A32A1B6C PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
|
|
In reply to this post by Jack-123
Jack,
The KSB2 will always use its own filter (OP1, OP2 or OP3 - they are all the same) to transmit. The important thing is that the K2 will use the BFO settings associated with FL1 for transmitting. So if you do not have the OP1 filter selected for SSB FL1, then the BFO frequencies will not be correct for the OP1 filter. It is not unusual for the actual widths of the variable filter to vary substantially from those 'widths' shown on the K2 display. That will depend on the exact crystals used in the filter, the varactor tolerances, and several other component tolerances. It is always best to measure the actual filter width with Spectrogram - that is more true for the wide filters than the narrow CW filters - any discrepancy seems to disappear at filter widths of about 400 Hz, which is 'amazingly' the design center width of the variable filter. You do not normally have to set FL2 to OP1. The important filter is FL1 because it is used for transmit. FL1 can also be used for receive, but if the best transmitted signal quality results in a less than desirable receive signal with FL1, then the recourse is to set FL2 to OP1 and use that for receive. BTW, I have almost never found that to be necessary in the many K2s that I have set up for SSB. As a first trial, set FL1 to OP1, then using Spectrogram, adjust the BFOs for both LSB and USB so the passband is centered between markers placed at 300 and 2600 Hz. Then try using FL1 for both transmit and receive. If all is well, then set FL2 thru FL4 as you desire. If the transmit signal needs adjustment, set the markers between 250 and 2550 Hz and try again. If your voice is quite unusually rich in low frequencies, you could go as low as markers between 200 and 2500 Hz. Should you have to go that low on the transmit filter, then you will likely have to set the FL2 filter to OP1 and adjust the BFOs for the most pleasant received signal. Take a look at the K2 dial calibration article on my website http://w3fpr.qrpradio.com. Part 3 of that article deals with the filter/BFO alignment and includes information about setting the SSB filters. 73, Don W3FPR Jack wrote: > I have been operating my K2 as a CW only radio for a few months and > have now just added the KSB2 SSB board. > > When I only had CW, I set the filter widths and BFO settings as per > the defaults advised and was very happy with it. However, since > setting the default values suggested in the KSB2 book, I've discovered > a few unanswered issues. > > Q1, Do I have to set FL1 to OP1? I was under the impression I had to. > But a friend has set his FL1 to 2.4KHz. I know this is the filter that > is used to transmit. Is it OK to narrow it down? Is there any benefit? > > Q2, Why does the book also say FL2 should be set to OP1 on SSB? Is > this a typo? > > Q3, I have now set the filters using spectrogram. EVERYONE should do > this, it is so easy and makes a huge difference. And the program is > free! Do it !!!! > I found that the default BFO values in the KSB2 book had CW and USB > pretty much perfect, but LSB was way off (3 or 400Hz). Retuning with > spectrogram has cured that and it sounds great on LSB now. Is it > normal to be so far off? > > Q4, The filter widths are actually much wider than that set on the K2 > display. ie 2KHz filter is actually about 3KHz wide. To get the same > "sound" as my other HF rigs I am having to set the filter widths much > narrower than expected. ie set the display to 1.2KHz width to get an > actual 1.8KHz width trace on spectrogram. Is this normal? Can this be > adjusted? Am I worrying about nothing? :o) > > Overall i am very happy with the recievers performance. The K2 has > taken over as main radio, pushing japanese sets aside. > But if anyone could advise on the above, that would aid my learing > process. Thats one of the reasons why i bought it :o) > > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
«
Return to Elecraft
|
1 view|%1 views
| Free forum by Nabble | Edit this page |