[Elecraft] KXV3B install - no problems

[Udo Langenohl - DK5YA]

Just got my KXV3-B as a replacement of the former KXV3-A. Installing 
complete after 1 hour. Removing the back panel makes things much easier 
btw. But there's an issue. The 1 mW calibration fails. Thats what the 
Elecraft Utility says:

Elecraft K3 Utility Revision 1.13.5.9
OS Version 6.1 Build 7601 Windows 7/Windows Server 2008 R2
K3 MCU revision 05.26. RS-232 speed 38400 bit/s.
Starting 1 milliwatt calibration
Calibrating at 1.900 MHz
Calibration power settled at " 1.800.00;"
Elapsed time: 5 seconds
Tx Gain calibration failed because transmit power did not reach the 
expected value
1 milliwatt calibration failed

Wait, there's more to come. I made a replacement because my guess was: 
KXV3-A has a damage.
I use my K3 mostly on VHF with transverters, especially on 144 MHz EME. 
I'm running a Xpol configuration with 4 antennas on 144 EME with two 
identical transverters, both in phase and locked by a common external LO 
with 10 MHz GPS control for Hpol and Vpol.
HPol RX is fed to the KXV3 XVTR In/Out while Vpol is fed to the AUX RF 
input. I can listen to both planes simultaneously using diversity receive.
But something very strange happens when I compare signals on both 
planes. I have a 144 MHz beacon nearby (just 25 miles away). That beacon 
is running 8 W on a Hpol antenna. On my Hpol (main RX via KXV3) input 
this beacon comes up to S9+35 dB while on Vpol (second RX via AUX) it's 
endstop (S9 +60dB). The beacon is in the line of sight, there's a lot of 
RF on my location from this beacon.
It's definetely not from the transverters or from mismatched antennas 
because when I change inputs and connect the Hpol transverter output to 
the AUX RF it's suddenly S9 +60 dB too. Both main and sub RX are exactly 
in the same configuration, filters, bandwidth, NB Off, etc..
I checked S/N on KXVR3-A (old board) and AUX few days ago with my 
HP8664A signal generator.
On 28.200 (TVTR IF) I measured:
Top values:
KXV3-A TVTR IN:   	-10dBm = S9+25dB
AUX IN:     		-10dBm = S9+60dB (!)
KXV3-A TVTR IN:      	+3dBm = S9+60dB
Huge difference of 13dBm
Low values:
KXV3-A TVTR IN:  	-134dBm = signal detectable
KXV3-A TVTR IN:     	-140dBm = none
AUX IN:        		-140dBm = signal detectable
Again a difference of at least 6dB or more.

Now, with the new KXV3-B it's even worse, at least 22 dB difference 
between the AUX IN and TVTR IN.

What the heck is going wrong here? MAIN RX dead?

73 Udo, DK5YA


Am 19.06.2015 um 12:04 schrieb Barry Simpson:
> I have just completed installing the KXV3B in my K3 s/n 1397. It already
> had a KXV3 in it (and a sub receiver which had to be removed and put back)
> and I am pleased to report that it all went together quite easily.
>
> I updated the firmware to the required beta version and the new preamp 2
> seems to work perfectly although no signals yet heard on 6/10/12m.
>
> I was initially troubled by the pre flashing on the display and thought
> there was some fault. However, I assume that it is an indicator that Pre 2
> is turned on. Please can you remove that feature as I find it mildly
> irritating.
>
> Mine is an early serial number K3 that I built around August/September 2008
> and until installing the KXV3B today, I had not even taken the top cover
> off for several years. It was a pleasant surprise to find the interior of
> the K3 looking absolutely pristine and dust free, other than for a very
> light coating on the PA heat sink, which I cleaned off. I also took the
> opportunity of replacing the battery (the original) although the voltage
> still showed 2.97 after all that time when I tested it.
>
>
> 73
>
> Barry Simpson  VK2BJ
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