KAT2 several questions

[Rolf Moberg, OH6KXL]

I've been using my K2 with KSB2 several months now. KAT2 was ordered and
built in this week.

Some problems:
Page 16 in KAT2 manual, Bridge Null Adjustment (C55)

I didn't get any better reading in adjustment. CALn was 010. Tuning was
very sharp and it was not easy to find the best value.

Power calibration in page 17 was the next problem. I dont't have good
external power meter so I tried calibration with RF probe. There weren't
any written instructios where to connect RF probe's crocodile clip and
where to touch by probe tip. I guessed and tried power calibration by
measuring DC voltage with probe from KAT2 J1 antenna jack soldering
terminals. However, when setting requested power to 5W and doing CALP I
noticed power level in LCD display was climbing smoothly from 6W to
upwards. DMM told the voltage in the beginning was about 12.8V and it
was goind up smoothly. Adjusting R1 (forward potentiometer) didn't help
to get any more clever or better voltages.

I decided to borrow a good wattmeter from somewhere. And re-installed
the top cover. Power calibration will be done later. I wanted to test
KAT2 antenna switch and antenna tuning.

Antenna switch is working. The big question are the relays. I can hear
them clicking when scrolling through ATU menu as described in manual.
However, no relay clicks are heard when pressing TUNE in CALP mode. Why?

Please help!

Rolf Moberg



_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Rolf Moberg, OH6KXL]

Rolf Moberg wrote:

> Antenna switch is working. The big question are the relays. I can hear
> them clicking when scrolling through ATU menu as described in manual.
> However, no relay clicks are heard when pressing TUNE in CALP mode. Why?

I admit an award to myself, "Year 2005 Wooden Eye". Of course you have
to select ATU AUTO to tune antenna.

My other two questions are still up to date.
CALn value 10 (should it get closer to 000?)
Power calibration with RF PROBE. How to do it? From where to get voltage
to DMM?

Rolf
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Mark Bayern-2]

I also had problems reading the K2 display when nulling C55. For me it
was much easier to find the null by using a DC voltmeter to measure
the reflected voltage signal into the PIC on the KAT2. My memory says
it was pin 4, but check the schematic to be sure.

Also, be very sure you have a good 50ohm dummy load connected to the
antenna output.

Mark  AD5SS



On 10/26/05, Rolf Moberg <[hidden email]> wrote:

> I've been using my K2 with KSB2 several months now. KAT2 was ordered and
> built in this week.
>
> Some problems:
> Page 16 in KAT2 manual, Bridge Null Adjustment (C55)
>
> I didn't get any better reading in adjustment. CALn was 010. Tuning was
> very sharp and it was not easy to find the best value.
>
> Power calibration in page 17 was the next problem. I dont't have good
> external power meter so I tried calibration with RF probe. There weren't
> any written instructios where to connect RF probe's crocodile clip and
> where to touch by probe tip. I guessed and tried power calibration by
> measuring DC voltage with probe from KAT2 J1 antenna jack soldering
> terminals. However, when setting requested power to 5W and doing CALP I
> noticed power level in LCD display was climbing smoothly from 6W to
> upwards. DMM told the voltage in the beginning was about 12.8V and it
> was goind up smoothly. Adjusting R1 (forward potentiometer) didn't help
> to get any more clever or better voltages.
>
> I decided to borrow a good wattmeter from somewhere. And re-installed
> the top cover. Power calibration will be done later. I wanted to test
> KAT2 antenna switch and antenna tuning.
>
> Antenna switch is working. The big question are the relays. I can hear
> them clicking when scrolling through ATU menu as described in manual.
> However, no relay clicks are heard when pressing TUNE in CALP mode. Why?
>
> Please help!
>
> Rolf Moberg
>
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Don Wilhelm-3]

Rolf,

Yes the null value is probably fine at 10, just get it as low as possible -
the null is quite sharp.  If you have an analog voltmeter you can read the
reflected voltage and see the null as a dip more easily than waiting for a
digital meter to update the reading.

For power calibration with an RF Probe, it will probably be more accurate
than using a wattmeter, but that depends on having an accurate non-reactive
dummy load.  You should be able to attach the RF Probe anywhere between the
ATU and the dummy load, the solder point for the center conductor on the
KAT2 board should be just fine.  Since the DMM attached to the RF Probe
reads RMS values, you can compute the power directly with V**2/R, and the R
value should be the resistance of your dummy load, prefferably 50 ohms.

Adjust the FWD pot on the KAT2 to make the K2 display match the measured and
calculated power output.

The output may increase after a time due to component heating, so try to
make the power measurements in short bursts.

73,
Don W3FPR

> -----Original Message-----
> Rolf Moberg wrote:
>
> > Antenna switch is working. The big question are the relays. I can hear
> > them clicking when scrolling through ATU menu as described in manual.
> > However, no relay clicks are heard when pressing TUNE in CALP mode. Why?
>
> I admit an award to myself, "Year 2005 Wooden Eye". Of course you have
> to select ATU AUTO to tune antenna.
>
> My other two questions are still up to date.
> CALn value 10 (should it get closer to 000?)
> Power calibration with RF PROBE. How to do it? From where to get voltage
> to DMM?
>
> Rolf
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com