++++++++++++++++++++ Date: Thu, 27 Feb 2003 10:02:16 -0800 From: Wayne Burdick Organization: Elecraft To: Elecraft Subject: [Elecraft] All PLL reference oscillator questions answered Here are the answers to several recent questions concerning the PLL reference oscillator modification: - The "d" seen on the LCD during CAL PLL indicates storage of one data point. What the firmware is doing is sweeping the reference oscillator through its full range using the 12-bit DAC, and storing the DAC value associated with each 100 Hz point. (When you actually tune the VFO later, these DAC values are recalled; pairs of them are used to interpolate down to 10 Hz steps.) - The K2 needs to be set to 40 meters in order to do CAL PLL, but the exact frequency doesn't matter. - A PLL reference oscillator range of 11 kHz is plenty. The present K2 manual, on page 57, specifies a minimum range of 9.8 kHz. - If a strong signal is present in the I.F. passband when the VFO is tuned across a 5 kHz synthesizer boundary, a brief audible artifact may be heard. This is not related to any reference oscillator modification; it's always been there. We tried experiment with muting the receiver during these shifts, but this results in a much more noticeable artifact (silence), so we left it as is. Hopefully, noone will be greatly inconvenienced by it. Technical details: Suppose the tuning rate is set to 10 Hz. On 5 kHz boundaries, the PLL reference oscillator will shifted by +/- 4.99 kHz, and at the same time the VCO divider is shifted by +/- 5 kHz. The net difference is only 10 Hz, but the counterbalancing shifts put a short impulse on the error voltage, which in turn shifts the VFO frequency some greater distance for a few milliseconds. (Other rigs that use DAC-controlled fine steps do the same thing; in the case of the Icom IC730, for example, it happens on 1 kHz boundaries.) The 5 kHz boundaries do not correspond to 0.00 and 5.00 kHz points on the dial. They will occur at a different point on each band, and take into account the BFO frequency and (in CW mode) the receive offset. 73, Wayne N6KR ++++++++++++++++++++ Date: Thu, 27 Feb 2003 11:53:35 -0800 From: Wayne Burdick Organization: Elecraft To: Brendan Minish Cc: Elecraft Subject: [Elecraft] Re: All PLL reference oscillator questions answered(Except for 1!) It will actually work with as little as 9.1 kHz of range, Brendan. We use 9.8 kHz to provide a safety margin. Sounds like you don't need to change anything. 73, Wayne Brendan Minish wrote: > > At 10:02 27/02/2003 -0800, Wayne Burdick wrote: > > >- A PLL reference oscillator range of 11 kHz is plenty. The present K2 manual, > >on page 57, specifies a minimum range of 9.8 kHz. > > My PLL only covers 12091.08 Khz to 12100.64 Khz (a Range of a little over > 9.5 Khz ) > During normal Dial tuning the following range is used > 12095.02 to 12100.08 > > there is no 'gaps' in the tuning range and other than the glitch when > crossing 5 Khz boundaries there are no other problems at the boundary > points such as pitch jumps etc. > > Am I ok with this range or should I put back the other xtal ? > > 73 > Brendan EI6IZ ++++++++++++++++++ Date: Thu, 27 Feb 2003 15:07:45 -0800 From: Eric Swartz WA6HHQ - Elecraft Organization: Elecraft To: Brendan Minish Cc: Elecraft Subject: [Elecraft] PLL reference oscillator - Range of 9.1 kHz or more OK Hi Brendan, As Wayne noted in his email, a PLL reference oscillator range of 9.1 kHz or more is sufficient, so you are OK. The manual is a bit too conservative and will be updated. Noticeable jumps in PLL tuning every 5 kHz usually indicate that you need to rerun CAL PLL with the K2 in its final configuration (with the top and bottom cover ON.) If you ran it with either cover off there will be a slight change in PLL calibration due to the proximity of the bottom cover and top cover + speaker magnet to the PLL circuitry. 73, Eric WA6HHQ Elecraft ------ Brendan Minish wrote: > My PLL only covers 12091.08 Khz to 12100.64 Khz (a Range of a little > over 9.5 Khz ) During normal Dial tuning the following range is used > 12095.02 to 12100.08 > > there is no 'gaps' in the tuning range and other than the glitch when > crossing 5 Khz boundaries there are no other problems at the boundary > points such as pitch jumps etc. > > Am I ok with this range or should I put back the other xtal ? > > 73 > Brendan EI6IZ ++++++++++++++++++ Date: Tue, 20 May 2003 10:10:28 -0400 To: Harry Yingst , Elecraft_Reflector From: Ken Wagner Subject: Re: [Elecraft] PLL Reference Oscillator Range Test That's fine... assuming you used the NEW X1 with the "CD" designator. I just built 3442 and it had a range of 13.6. 73, Ken K3IU ~~~~~~~~~~~~~~~~~ At 10:05 AM 5/20/03, Harry Yingst wrote: >I've completed my K2 up to the Alignment and Test, Part II. > >All has gone pretty well so far. > >But when I preform the PLL Reference Oscillator Range Test my range is >13.98 kHz (the manual says the acceptable range it 9.8 - 13). > >Any thoughts on where to start looking? > >Or is this an acceptable range? > >Thank you > > > >===== >Harry - AB2PN ++++++++++++++++++ From: "Lyle Johnson" To: "Elecraft_Reflector" Subject: RE: [Elecraft] PLL Reference Oscillator Range Test Date: Tue, 20 May 2003 07:16:09 -0700 > But when I preform the PLL Reference Oscillator Range Test my range is > 13.98 kHz (the manual says the acceptable range it 9.8 - 13). It's fine, nothing is wrong, keep going... -Lyle KK7P ++++++++++++++++++ Date: Wed, 28 May 2003 21:15:40 -0700 From: Wayne Burdick Organization: Elecraft To: Daniel Reynolds Cc: elecraft at mailman.qth.net Subject: [Elecraft] Re: PLL Reference Oscillator Hi Daniel, The PLL reference crystal we use is a special temperature-stable type with a specific motional inductance that we custom order from ECS. Results with a standard type purchased from Digikey are likely to be poor. But we will send you one at no charge (just contact parts at elecraft.com). There are many other possibilities besides the crystal: a poorly-tinned or stripped lead on the toroid in the source circuit; a hair-line solder bridge that conducts once the board reaches a certain temperature, a bad PLL chip, etc. You might contact Gary (support at elecraft.com) for more ideas. 73, Wayne N6KR Daniel Reynolds wrote: > > I've had an intermittent PLL reference oscillator (based on frequency readings > at TP3) for about the last month. Things would perk up if I grounded or used a > DMM to probe between D16/L31 and ground. All voltages seem to be correct. I've > replaced Q19 (J310) and D18 (1N4148) and the situation has not improved. Today, > I was unable to resuscitate the oscillator. I'm guessing that X1 may be the > culprit..... +++++++++++++++++ Date: Mon, 02 Jun 2003 15:52:23 -0700 From: Eric Swartz WA6HHQ - Elecraft Organization: Elecraft To: Trevor Jacobs Cc: Elecraft Mailing List Subject: Re: [Elecraft] PLL Ref Osc range question... 14 kHz is OK. 73, Eric WA6HHQ --- Trevor Jacobs wrote: > The only > thing I see that may be an issue is that I'm getting 14 KHz of swing on the > PLL Ref Osc vs. the specified 13 KHz max swing. It tunes from 12099 KHz > down to 12085 KHz. CAL PLL worked fine, but I'm wondering if this will cause > any problems to arise? > 73's Trev KG6CYN +++++++++++++++++