Hi I have a method that works well for me to adjust the power/SWR bridge.
You will need to make up two additional dummy loads besides your 50 ohm. These need to be 25 ohms and 100 ohms. I used 2 50 ohm 2 watt MOS resistors mounted inside a PL239 connector wired in series for the 100 ohm and in parallel for the 25 ohm. For the kAT2 you will also need UHF to BNC adapters. After you do the procedure below from the manual set the forward power pot per the manual. Set the reverse power pot to about the same position as the forward pot. Now using about 2-3 watts with the 25 ohm load note the SWR reading. Now install the 100 ohm load and adjust the null in very small amounts until you get the same reading with both the 25 and 100 load. It does not matter what the reading is yet, just so it is the same. Once that is done adjust the reverse pot so the K2 displays 2.0:1 with either load. Now go back and check the power and SWR with the 50 ohm load. The SWR should be 1.0:1. If the power is off adjust the forward power pot to correct it and recheck the reverse again with the 25 and 100 ohm loads to make sure you still get 2.0:1. All of this will interact a little so you may need to go through it several times. Hope this helps Thanks Don Brown KD5NDB ----- Original Message ----- From: "Don Wilhelm" <[EMAIL PROTECTED]> To: "JT Croteau" <[EMAIL PROTECTED]> Cc: <elecraft@mailman.qth.net> Sent: Friday, September 28, 2007 8:22 PM Subject: Re: [Elecraft] KAT2: C55 Adjustment > JT, > > Use a fully insulated tuning tool - both ends of the trimmer cap are > floating above ground, so you will see a lot of 'hand capacitance' > effects with a metallic screwdriver. If you can achieve a null below 9 > or 10, that is a normal low value. > > Tune slowly and you can obtain the null. If you have a high impedance > input analog reading meter, you can do it easier than the 'no tools' > manual method. Connect your meter from the hot side of R2 to ground and > tune the cap for a minimum reading - the null is easier to see on an > analog meter - just tune for the smallest voltage, then check the value > displayed on the K2 - if it is less than 10, all is good. > > If you cannot achieve a decent null, then you may have a significant > amount of residual inductance or capacitance in the KAT2 - usually due > to a non-operating relay. If that is the case, first inspect the > soldering on each of the relays (yes, you will have to lift some > inductors to do that) to be certain all pins are soldered. > > 73, > Don W3FPR > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
