[Elecraft] KXV3 Issues - endless frustration

[Wayne Burdick]

Udo,

I'm not sure how the 1-mW calibration could fail. But I'll keep trying to duplicate the problem on my K3 (no luck so far). The rest of the crew will be back Monday, and they may have other suggestions.

The KXV3B should have essentially the same path loss, but better port isolation, than the KXV3A. So your signal strength tests don't make sense, either.

Note that the KXV3B includes the second preamp, which has a lot more gain than the main preamp. Are you using preamp 2 on the IF band?

73,
Wayne
N6KR





On Jun 19, 2015, at 1:50 PM, Udo Langenohl - DK5YA <dk5ya at dk5ya.de> wrote:

> 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 at least 13dBm
> Low values:
> KXV3-A TVTR IN:      -134dBm = signal detectable
> KXV3-A TVTR IN:         -140dBm = none
> AUX IN:                -140dBm = clear signal detectable
> Again a difference of at least 6dB or even 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
> 
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