[600MRG] New K3 firmware with 10 and 18 MHz XVTR IF selections

[Matt Zilmer]

Hi Wayne,

I have 4.81 working with two 10 MHz-IF transverters:
- 100 to 520 KHz receiving converter
- 420 to 421 MHz transverter

Both are homebrew, really old, and operate at 1 mW levels.  I can copy
some of the local CW activity on 420, but only two signals so far.
Power out looks good: 8-10W.  The LF converter is receiving local sig
gen signals, but I haven't heard anything else on the air except some
local household gudge.  LF is really a night time band anyway.

Can't tell you about the 18 MHz IF.  No xvtrs for that IF here.

73,
matt

On Sat, 25 Jan 2014 10:12:20 -0800, you wrote:

>Hi all,
>
>The attached K3 field-test firmware adds 10 and 18 MHz as transverter I.F. selections in the CONFIG:XVn IF menu entry. Please let me know if you get a chance to try either band.
>
>(For various technical reasons, it would be harder to add the 1.8- and 3.5-MHz bands as I.F. selections, though this is still on the list for future consideration.)
>
>Note that the K3 uses narrow band-pass filtering, optimized for the ham bands. In the case of 10 MHz, we align the BPF at 10.1 MHz. If you plan to use the K3 with a 600-meter transverter and a 10-MHz IF, this puts the IF at about 10.5 MHz. You may find that the receive gain could be somewhat lower at this frequency. If this is an issue, you can easily adjust the 30-meter BPF to handle both the 10.1-MHz end and the 10.5-MHz end of the passband.
>
>To do this, inject a strong signal at 10.5 MHz, tune it in, and while watching the S-meter, peak trimmer capacitor C179. Then inject 10.1 MHz, tune that in, and peak C183. 
>
>This may result in some ripple in the filter's passband. But the peaks will be where you need them -- in both the ham band (10.1) and at the required I.F. for 600 meters (10.5). 
>
>You should also verify that the K3's synthesizer is working well at 10.5 MHz. Tap DISP, then use VFO B to locate the "PLL1" voltage display. Tune the VFO from 10.1 to 10.5 MHz while watching this voltage. It should remain between about 1.5 and 7 volts. If the voltage goes outside this range, or you seen an asterisk (*) in the PLL1 display, re-run the VCO CAL routine described in the owner's manual. Hopefully this will not be necessary, though I did find one K3 that required this step.
>
>I didn't hear any inherent receiver spurs when tuning from 10.475 to 10.525 MHz.
>
>73,
>Wayne
>N6KR
>

Matt Zilmer, W6NIA
www.elecraft.com
831-763-4211  x129
Skype: matt.zilmer