[Elecraft] Elecraft transveters and freq. counter/signal generator

[Tom Hammond]

Hi Paul:

At 09:00 PM 7/6/2005, you wrote:
>I found a reasonable kit for the main guts of a homemade freq. counter at
>Almost All Digital http://aade.com/index.html#dfd specifically his DFD4a
>http://aade.com/DFD4A/dfd4a.htm I got mine in the assembled version because
>it comes with the TCXO already calibrated. You still need to wire it and
>provide a suitable enclosure but that's the easy part. Cost ~$80 plus spare
>connectors, switches, battery and a box. Used it to align the 4Mhz osc on K2
>#4826 which later zero-beat to WWV within 30Hz.

With all due respect, Paul, you can manually zero the K2 to well within 
10Hz to 20Hz of WWV for FREE, using the procedure outlined by Wayne Burdick 
below:

   Subject: 4 MHz oscillator cal method for the K2
   Date: Wed, 20 Aug 2003 13:57:44 -0700
   From: Wayne Burdick <n6kr at elecraft.com>

   All of the methods that have been described for
   calibrating the K2's 4-MHz oscillator will work. But I use
   a different technique that allows C22 on the Control board
   to be set to precisely to the correct position, with no
   guesswork.

   This method relies on the following simple observation. If
   you tune in an on-air signal at a known frequency, the
   difference between the *measured* VCO and BFO (using CAL
   FCTR) *must* equal that frequency, or C22 is not set
   correctly. (Actually, this holds for 160-17 m; on 15-10 m
   it's the sum, or VCO + BFO, that must equal the signal's
   frequency. But it's easier to do the adjustment of C22 on
   17 m or lower because you don't have to do any math at
   all, as I'll explain below.)

   Here's the procedure. It requires revision 2.XX firmware,
   and assumes you have already done Alignment and Test, Part
   II, at some point. The K2 should also be allowed to come
   up to room temperature.

   1. Tune in a signal at a known frequency. Use one that's
      at an *exact* kHz boundary, so you can easily see when
      the VCO and BFO readings match in step 2. (I use WWV at
      10, 15, or 20 MHz.) Use USB or LSB mode rather than CW,
      so that there will be no CW receive offset. In the case
      of a K2 I was calibrating, the VFO read 10000.17 when
      the signal was tuned in perfectly. If it had read
      10000.00, no further improvement would have been
      possible.

      TIP: Zero-beat the carrier precisely, or listen to a
      voice signal and adjust the VFO for the best quality.
      The more accurately you tune in the signal, the more
      accurately you'll be able to set C22, below.

   2. Run CAL FCTR. Now alternately move the K2's internal
      counter probe between TP1 (VCO) and TP2 (BFO),
      adjusting C22 in small increments until the kHz and Hz
      digits at the two test points match as closely as
      possible. In my case, the two readings matched at
      14913.60 and 4913.60. The difference is exactly
      10000.00--the frequency of the on-air signal.

   3. Put the counter probe on TP1 (VCO), switch to 40
      meters, and run CAL PLL.

   4. Put the probe on TP2 (BFO) and run CAL FIL. For each
      operating mode, vary each filter (or BFO) setting up 1
      count, then back down, to force the K2 to take a new
      BFO measurement for each and store it in EEPROM.

   The VFO dial should now be very well calibrated.

   If we get a lot of positive feedback on this method, we'll
   post it as an application note.

   73,
   Wayne
   N6KR

Of course, it's still a good excuse to buy an AADE Freq Counter... which 
ARE pretty neat devices... heheh!

73,

Tom Hammond    N0SS