Re: [Elecraft] KAT2 Null Bridge Adjustment Problems
Thanks to everyone who gave me suggestions about how to troubleshoot this problem. It has now been solved, and the solution was not as esoteric as one might have imagined. I had a friend, who has built a number of Elecraft kits, look over my KAT2. He discovered that I had left out R3! Now, once that resistor was in place the readings nulled appropriately. Why I left that resistor out during construction I have no idea. It took another set of eyes to discover my omission. The KAT2 is now calibrated and working quite well. Again, thanks to all who offered help. This is a great list with great people! 73, Carl N8VZ k4zm wrote: I've built the KAT2 and have become "stuck" at the Bull Bridge Adjustment stage (P. 16 Rev. D Manual). No matter where I place the trim capacitor C55, I get "Hi" on the screen when I do a Tune in CALn mode. Carl: I usually make this adjustment using an old analog voltmeter on the lowest dc votage scale. You can see the null much easier. I connect the meter negative lead to ground and the postive meter lead to pin 4 of U1. Then follow the directions in the manual. If it will not null then you probably have a problem with T1. I would guess that 95% of the problems with a null function are caused by T1 problems. (poorly tinned transformer leads, the omission of the link between pins 5 & 6 of T1 and the leads of T1 not installed in the correct holes in the board) 73 Jim Younce K4ZM K2 SN: 18 ___ 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
Re: [Elecraft] KAT2 Null Bridge Adjustment Problems
I've built the KAT2 and have become "stuck" at the Bull Bridge Adjustment stage (P. 16 Rev. D Manual). No matter where I place the trim capacitor C55, I get "Hi" on the screen when I do a Tune in CALn mode. Carl: I usually make this adjustment using an old analog voltmeter on the lowest dc votage scale. You can see the null much easier. I connect the meter negative lead to ground and the postive meter lead to pin 4 of U1. Then follow the directions in the manual. If it will not null then you probably have a problem with T1. I would guess that 95% of the problems with a null function are caused by T1 problems. (poorly tinned transformer leads, the omission of the link between pins 5 & 6 of T1 and the leads of T1 not installed in the correct holes in the board) 73 Jim Younce K4ZM K2 SN: 18 ___ 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
[Elecraft] KAT2 Null Bridge Adjustment Problems
I've built the KAT2 and have become "stuck" at the Bull Bridge Adjustment stage (P. 16 Rev. D Manual). No matter where I place the trim capacitor C55, I get "Hi" on the screen when I do a Tune in CALn mode. Anyone have any ideas where I should look for the culprit here? Prior to this, the KAT2 checked out just fine in the preliminary tests on p. 13 of the manual. I just need some direction as were to start looking for the possible problem. The only thing that I can think of is a possible bad C55. Thanks and 73, Carl N8VZ ___ 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
