+++++++++++++++++++++ Date: Thu, 28 Feb 2002 15:10:50 -0800 From: Wayne Burdick Organization: Elecraft To: Alex Turner Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] Filters OP1,OP2,etc. Hi Alex, "OP1" means "optional crystal filter #1." While we can imagine multiple optional filters being installed in a K2, as of now, the only optional filter is the one on the SSB adapter, so that's what you get with any of the "OPx" filter selections. The K2 manual provides suggested SSB and CW filter bandwidths and BFO frequencies. More detail is provided in the KSB2 manual--use that if you have the SSB adapter installed. Wayne N6KR Alex Turner wrote: > > Trying to get the K2 back in working condition after the upgrade to 2.0. > Can someone explain the OP1 and the other OPs? Do they all have the same > bandwidth and the BFO can be changed to tailor the pitch.? +++++++++++++++++++++ Reply-To: From: "Ron D' Eau Claire" To: Subject: RE: [Elecraft] Filters OP1,OP2,etc. Date: Thu, 28 Feb 2002 14:31:22 -0800 > Trying to get the K2 back in working condition after the upgrade to 2.0. > Can someone explain the OP1 and the other OPs? Do they all have the same > bandwidth and the BFO can be changed to tailor the pitch.? > > Alex N4BYJ All of your filter, BFO, etc., settings should have been preserved when you installed the Rev 2 firmware. If you lost them, something didn't happen right! In any case, OPT1 is the filter on your SSB adapter board. It is the only active "OPT" filter that I know of at this time. If you have the SSB board installed, OPT1 will come up in filter position 1 for CW because it makes a very nice wideband filter for casually tuning across the CW frequencies. The bandwidth of the OPT1 filter is fixed. All you can do is adjust the BFO. The BFO is set up as described in your KSB2 manual. The BFO setting for OPT1 in FL1 position is ALWAYS used for transmit. So that one is critical for the proper sound on the air. You can then use OPT1 in the other filter settings (FL2, FL3, etc.) with different BFO settings to simulate a sort of "passband tuning" characteristic by shifting the relationship of the passband to the BFO. This will not affect your transmitted signal sound. The K2 reverts to the FL1/OPT1 BFO setting for transmit regardless of the filter being used for receive. Ron AC7AC K2 # 1289 ++++++++++++++++++ From: "Don Brown" To: , "Elecraft" Subject: Re: [Elecraft] (no subject) Date: Thu, 4 Jul 2002 13:43:13 -0500 Hi OP1 - OP5 are all the same and select the SSB module. I guess the other O= P3-5 may be for future filter modules but for now OP1 is used on transmit= and OP2 is used on receive. You can set up the filters for OP2- OP5 and = shift the BFO setting for each to simulate IF tuning Your tinny sounding audio sounds like you need to install the filter flat= tening mod and set the SSB filter with Spectrogram Don Brown KD5NDB ----- Original Message ----- From: ham_tech at juno.com Sent: Thursday, July 04, 2002 12:14 PM To: elecraft at mailman.qth.net Subject: [Elecraft] (no subject) Hi, What is the difference in OP1-5? I know that the OP's are supposed to cover SSB and CW scanning at the same time. Daniel +++++++++++++++++++ From: "Don Brown" To: "Vic Winton" , "Elecraft" Subject: Re: [Elecraft] OP1 - 5 Date: Fri, 5 Jul 2002 07:37:19 -0500 Hi Sorry for the confusion. I meant to say you can set all of the all of the= filters FL1- FL4 to OP1 and vary the BFO on FL3 and 4 to simulate IF tun= ing. As far as I can determine OP1 - OP5 are all the same and the bandwid= th is fixed by the SSB module. Maybe at some time Elecraft will offer a d= ifferent filter module that will take advantage of OP2-OP5 but for now it= doesn't matter which one you select they are all the same. Don Brown KD5NDB ----- Original Message ----- From: Vic Winton Sent: Friday, July 05, 2002 4:57 AM To: elecraft at mailman.qth.net Subject: [Elecraft] OP1 - 5 All, Do I read this right? Can I really set OP 2 - 5 differently and therefore do as Don suggests? So,if I understand this correctly, for ssb use I can set FL1-4 as follow= s: FL1 as OP and FL2-4 as cw the filter at various widths (say 2.0, 1.8 etc= ). But IN ADDITION my FL1 setting can be varied if I switch between OP1 - 5. Thus I get a switchable IF shift effect. Is this correct? Presumably the OP 1-5 switching could be put on to one of the programmabl= e buttons to make it easier than scrolling througgh the menus... Why did I not realise this before? Regards, Vic GW4JUN K2 1926 snip... Hi OP1 - OP5 are all the same and select the SSB module. I guess the other OP3-5 may be for future filter modules but for now OP1 is used on transmi= t and OP2 is used on receive. You can set up the filters for OP2- OP5 and shift the BFO setting for each to simulate IF tuning Don Brown KD5NDB snip... ++++++++++++++++ From: "ZOOM" To: "Don Brown" , "Vic Winton" , "Elecraft" Subject: Re: [Elecraft] OP1 - 5 Date: Fri, 5 Jul 2002 10:21:53 -0400 Yes OP-1-5 are all the same except if you have done the 2nd_xil_ssb_mod. The mod can only be activated by OP-1. Therefore if you set your other filters on OP-2-5, the mod is disabled on those filter settings. You can set all your SSB filter position to OP-1 and adjust each filter setting individually using spectrogram and get the benefit of the mod on each setting. Robert VE3RPF ----- Original Message ----- From: "Don Brown" To: "Vic Winton" ; "Elecraft" Sent: Friday, July 05, 2002 8:37 AM Subject: Re: [Elecraft] OP1 - 5 Hi Sorry for the confusion. I meant to say you can set all of the all of the filters FL1- FL4 to OP1 and vary the BFO on FL3 and 4 to simulate IF tuning. As far as I can determine OP1 - OP5 are all the same and the bandwidth is fixed by the SSB module. Maybe at some time Elecraft will offer a different filter module that will take advantage of OP2-OP5 but for now it doesn't matter which one you select they are all the same. Don Brown KD5NDB +++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: "'Leroy Buller'" , Subject: RE: [Elecraft] Filter Challenged...I'm so confused Date: Fri, 7 Mar 2003 08:59:45 -0800 You can do anything that you like with filter positions FL2, FL3 and FL4 in the SSB modes. When you go into CAL FIL and change the bandwidth to OPT1, you are simply selecting the fixed-bandwidth SSB filter on the SSB board instead of the variable bandwidth CW filter on the R-F board. As I recall, OPT2, OPT3 and OPT4 act identically with OPT1 - any of those selections will choose the fixed-bandwidth SSB filter on the SSB module. It's a good idea to use OPT1 just in case some future firmware update changes that. Your understanding is right. You MUST select OPT1 for the filter in FL1 position in the USB and LSB modes because the SSB module automatically uses whatever you selected for FL1 as the "transmit" filter. If you do not have OPT1 selected in FL1 position, the SSB module won't work in transmit. Filter positions FL2, FL3 and FL4 can be ANYTHING you choose: the OPT1 filter or the variable-bandwidth CW filter with any bandwidth setting you might want. It will have no effect on transmit. So why would one want to use OPT1 in the FL2, FL3 or FL4 positions? Remember that you have three things you can "adjust" in CAL FIL: 1) The filter you will use - either the fixed bandwidth OPT1 filter or the variable bandwidth filter. 2) If you choose the variable bandwidth filter you can set the bandwidth you want. 3) The two frequencies of the Beat Frequency Oscillator (BFO) associated with that Filter Position. The BFO frequency determines the frequency of the audio signal that you hear in the speaker when a signal appears in the filter passband. For SSB, you want to adjust the BFO so that a signal near the lower edge of the filter passband will produce a tone of about 400 Hz in the speaker, and a signal near the upper edge of the passband will produce a tone of about 2400 Hz in the speaker. That corresponds to the minimum audio spectrum for good "communications" speech quality. You have two BFO frequencies to set for EACH filter position. In SSB there is one for upper sideband and one for lower sideband. One BFO frequency is below the filter bandpass so filter will pass one of the SSB sidebands, and the other BFO frequency is above the filter bandpass so the filter will pass the other SSB sideband. That's how upper sideband (USB) and lower sideband (LSB) are selected. You do the same things in CW mode. That's how CWn (normal) and CWr (reverse) are set up. One reason for using the OPT1 filter in SSB for FL2 or 3 or 4 is to produce the equivalent of "passband tuning". You can define different BFO frequencies in FL2 or 3 or 4 that will "shift" the passband of the filter to higher or lower frequencies. For example, placing the BFO closer to the edge of the filter passband will cause the audio you hear to be lower-pitched, and placing the BFO farther from the edge of the filter passband will cause the audio to be higher-pitched. As long as you leave the BFO settings in FL1 alone, these changes will have NO effect on your SSB signal "on the air". Of course you are free to use the variable bandwidth filter in FL2, 3, or 4 and adjust the bandwidth as well. The variable bandwidth filter is designed for narrow CW bandwidths, so it is not as smooth when used out at "phone" bandwidths near 2 kHz, but it does work well enough. I use it set narrower for data modes that employ SSB transmit so I can narrow the receiving bandwidth. Bottom line: you did NOT "go wrong". You have simply made some choices that you can change at any time. One final note: the stock K2 filter is NOT 2.4 KHz wide. It's closer to 2 kHz. That's right at the minimums for good communications speech intelligibility. That was done on purpose by Elecraft since the narrower the filter, the more the RF is concentrated into a narrower spectrum and the more "punch" the signal will have in getting through when the signal is not too strong. The disadvantage is that the BFO frequencies must be set carefully for this filter to deliver the proper performance. It needs to pass the range of about 300 to 400 Hz up to 2300 to 2400 Hz to work at it's best. That's why it is so important to make final adjustments of your BFO frequencies in FL1 position for the best-sounding signal on the air and then leave those settings along. If you don't like the sound of SSB reception with FL1 set for best transmit quality, adjust the BFO frequency in FL2, 3, or 4 positions for the receive quality you like best. Ron AC7AC K2 # 1289 +++++++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: "'Wallace, Andy'" , Subject: RE: [Elecraft] Filter Challenged...I'm so confused Date: Sat, 8 Mar 2003 09:00:48 -0800 Sometimes I am dense.. When I answered this question yesterday I failed to mention that what you are describing is CORRECT in other rigs. In the K2, the Local Oscillator frequency is shifted automatically by the firmware when you change the BFO frequency to compensate! I'm so used to that "effect" that I forget it's there. Lou, W7HV brought that to my attention this morning. Thanks Lou! In an "ordinary" rig, you would be shifting the pitch of the SSB signal by simply moving the BFO, but not in the K2. There used to be an excellent write up on the Elecraft reflector by Wayne on how the K2's system works called "The Mechanics of CAL FIL" that goes into great detail. I might still be there, but for me finding something under the "Builder's Resources" on the web site is harder than fining a 1/4 watt resistor in the bottom of my junk box. You aren't the first op to spot that behavior and question it . Ron AC7AC K2 # 1289 -----Original Message----- From: Wallace, Andy [mailto:awallace at mc.com] Sent: Friday, March 07, 2003 9:33 AM To: 'rondec at easystreet.com'; elecraft at mailman.qth.net Subject: RE: [Elecraft] Filter Challenged...I'm so confused > -----Original Message----- > From: Ron D'Eau Claire [mailto:rondec at easystreet.com] > > One reason for using the OPT1 filter in SSB for FL2 or 3 or 4 is to > produce the equivalent of "passband tuning". You can define different > BFO frequencies in FL2 or 3 or 4 that will "shift" the passband of the > filter to higher or lower frequencies. But if you do this, will you be transmitting on the correct frequency with FL2-4 shifted as you describe? Or will the received signal (using FL2-4) BFO shift -- to do "passband tuning" in effect -- cause you to tune in the received station at a frequency different from where your K2 will transmit, using FL1 in the transmit path? I hope you understand what I'm asking. I don't have a KSB2 (yet) so I can't experiment. Andy ++++++++++++++++++