[Elecraft] Re: FD W4ZV 1B QRP Single Op

[Bill Tippett]

Hi Wayne,

At 11:08 AM 6/29/04, wayne burdick wrote:

>>  QSK...
>
>Where did you have T-R set in the menu? At T-R = 0.00, the receiver is 
>unmuted very fast, which can cause a small receive artifact with certain 
>narrow crystal filter and DSP settings. But we recommend using T-R = 0.01 
>or higher anyway. For casual operation, use T-R = 0.02 to 0.05.
>
>The time required to cleanly switch the VCO between RX and TX is around 
>10-15 ms. We put a high value on completely clickless and chirpless CW 
>keying, and adjusted firmware delays accordingly. Still, wiith TR = 0.01, 
>you should be able to hear between characters (not words) even at 50 WPM. 
>If not, you may have an assembly or component problem somewhere.
>
>It's likely that we could improve VCO lock time and obtain between-dits 
>receive at such speeds. This is one item on my list of possible future 
>mods for the K2.

         T-R was default at 0.02 and I was normally sending at
25-30 WPM.  I'll give 0.01 a try and see if I notice a difference.
I strongly applaud your efforts on CW cleanliness.  I would
much rather live with a few QSK thumps in the receiver than
be putting out clicks on transmit!

>>Power meter...
>
>It's a good idea to adjust POWER when not keying. During transmit, a small 
>additional amount of hysteresis is added to the POWER control to improve 
>noise margin, and this can increase the power-control step size.
>
>You can also usually adjust one resistor value in the BFO attenuator to 
>improve power-setting accuracy. Some JFETs (Q24) have much higher 
>transconductance than average, leading to coarser steps from the 8-bit 
>DAC. To compensate, try increasing the value of R98 from 270 to as high as 
>470-820 ohms. (This experiment is best done with a small trim pot 
>installed; replace the pot with a fixed resistor close to the final pot 
>value.) If you adjust R98's value, make sure that the rig can still reach 
>at least 10 watts on all bands with POWER set to 10.0.

         OK.  Good to know to adjust it when not keying.  I was in
the habit of monitoring that I was <5W out key down when adjusting the
Emtech ZM-2 (in it's Tune mode) and then readjusting K2 power after
switching the ZM-2 out of Tune mode (when an attenuator is switched out
of its internal circuit.  In general, I've found the K2's meter to be very 
close
to my Mirage MP1 at home, but the coarseness of the adjustment during
transmit was my main concern.  Now I know to set it when not keying.

>>CW messages...
>
>In order to store the maximum possible characters in the K2's CW message 
>memories, the firmware "quantizes" your sending into standard-length dots, 
>dashes, and spaces. This is not as forgiving as using a "times-8 clock" 
>for recording, which is characteristic of some keyers. But such keyers 
>have a much larger EEPROM than the K2 does, or they don't provide as many 
>characters of storage. It's conceivable that we could go to a larger part 
>in the future and use a times-8 or even times-16 sample clock. (Another 
>item on my future mods list....)

         As I said, with multiple tries, I could get it to sound OK,
but was wondering if I should have been doing something
differently.  This was actually the first time I've used the K2's
memories and Fast Play since I built it.

         Thanks for a very nice FD transceiver!  By the way, it
barely made a dent in my 75AH deep cycle battery plus small
180 ma solar panel.  At the end of the operation, my battery was
reading 12.71 Volts, which indicates nearly a full charge.  Since
I was relegated to mostly S&P-ing, I probably could have used
a 7AH battery for the entire contest!  I also had the K2 set to
LCD - Day all the time since I used a Coleman lantern for lighting
at night.  By the way, could you explain exactly what the K2's
performance tradeoff is when using OPT - BATT?  Does this give
mainly less sensitivity or less dynamic range?  It sounds like
sensitivity to my ears so I left it set to OPT - PERF for the entire
contest, but would like to know in case I am ever running low on
reserve battery power.

                                 73,  Bill  W4ZV