[Elecraft] K2 TX alignment problems continue
Hi all, The symptom of my problem is: 1. when setting k2 power to 5 watts, I get a reading of 2.2 amps with abt 0.8v drop 2. when looking at power output with an external wattmeter, 5 watts reflecting on the external wattmeter shows as 3.8 on the k2. Similarly, 10 watts on external wattmeter is reading 6.9 on the k2 at an 2.8 amps. Cranking the rf power all the way clockwise shows 15 watts on k2 and hi pwr message (cal curr set to 3.25) and external wattmeter shows 19 watts. I examined T2 and had it too tight to the RF board so have re-installed with gap. Part 2 alignment works perfectly, part 3 resistance checks okay. I do not have a signal generator that can do 0.14vrms so have not done those receiver checks. In performing the transmit mixer, buffer, etc, tests, the readings do not look right at all. Xmit mixer output (pin 4 at U10) reads 0. Buffer output (pin 6 U9) reads 0.05 Band-pass Filter Output (W6) reads 0.014 T-R switch #1 Output reads 0.012. Any clues or things to test? Neal ___ 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] K2 TX alignment problems continue
Neal Campbell and Sarah Ferrell wrote: The symptom of my problem is: 1. when setting k2 power to 5 watts, I get a reading of 2.2 amps with abt 0.8v drop 2. when looking at power output with an external wattmeter, 5 watts reflecting on the external wattmeter shows as 3.8 on the k2. Similarly, 10 watts on external wattmeter is reading 6.9 on the k2 at an 2.8 amps. Cranking the rf power all the way clockwise shows 15 watts on k2 and hi pwr message (cal curr set to 3.25) and external wattmeter shows 19 watts. The RF detector seems to be reading low. Check the RF detector components on the RF board: R66, R67, R68, R69, D9. Make sure the resistors are the correct values and the diode is the correct type. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ 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] K2 TX alignment problems continue
Neal: How sure are you that the wattmeter is reading correctly? What scale are you using to read the output on and are you operating the radio into a dummy load or an antenna? Also where are you measuring the 0.8 volt drop? That sounds like a pretty big drop in voltage with only 2.2 amps of current. One word of note - I have built thirteen K2's and have never seen one that would produce 19 watts output at any setting of the power control or any band. 73 Jim Younce K4ZM ___ 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] K2 TX alignment problems continue
k4zm wrote: I have built thirteen K2's and have never seen one that would produce 19 watts output at any setting of the power control or any band. The power output of the K2 is determined by an ALC feedback mechanism. When you set the power control to 5 watts, the ALC circuit increases the drive until the RF detector indicates that 5 watts is being output. If the RF detector indicates that less power is being produced, the ALC circuit will continue to increase drive. Although the RF detector in the basic K2 is not adjustable, the one in the KAT2 is. If you have a KAT2 it's quite easy to adjust the wattmeter circuit to fool the K2 into producing more power than the power control says. I had my K2 making 22 watts on 40 meters a couple of years ago when I was using the basic K2 to drive an external amplifier (now I have a KPA100). -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ 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] K2 TX alignment problems continue
The good news is that I did a diode dance, had the rf probe diode in D9, had the real d9 substituted for a 4148 and a 4148 in the rf probe. Will swap them around and redo the tests! Neal On Feb 13, 2005, at 6:00 PM, Vic Rosenthal wrote: Neal Campbell and Sarah Ferrell wrote: The symptom of my problem is: 1. when setting k2 power to 5 watts, I get a reading of 2.2 amps with abt 0.8v drop 2. when looking at power output with an external wattmeter, 5 watts reflecting on the external wattmeter shows as 3.8 on the k2. Similarly, 10 watts on external wattmeter is reading 6.9 on the k2 at an 2.8 amps. Cranking the rf power all the way clockwise shows 15 watts on k2 and hi pwr message (cal curr set to 3.25) and external wattmeter shows 19 watts. The RF detector seems to be reading low. Check the RF detector components on the RF board: R66, R67, R68, R69, D9. Make sure the resistors are the correct values and the diode is the correct type. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ 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] K2 TX alignment problems continue
I have retested and the output as shown on the k2 tracks more closely with the watt meter. On 40m with the k2 showing 10 watts, I am seeing 2.6 amps. When I push it to the maximum, it shows between 14 and 16 watts depending on the band. I have set cal cur to 3.25amps. When I crank it to full output, after abt 10 seconds I see the mpu reset (drops out of xmit and the elecraft name appears in the lcd). Is this a sign of trouble or some safety logic to keep it out of 'full carrier' mode for long? I have aligned all the bands per the procedure and it acted normally (peaking a decent amount based on the can/capacitor. 73 Neal On Feb 13, 2005, at 9:07 PM, Neal Campbell and Sarah Ferrell wrote: The good news is that I did a diode dance, had the rf probe diode in D9, had the real d9 substituted for a 4148 and a 4148 in the rf probe. Will swap them around and redo the tests! Neal On Feb 13, 2005, at 6:00 PM, Vic Rosenthal wrote: Neal Campbell and Sarah Ferrell wrote: The symptom of my problem is: 1. when setting k2 power to 5 watts, I get a reading of 2.2 amps with abt 0.8v drop 2. when looking at power output with an external wattmeter, 5 watts reflecting on the external wattmeter shows as 3.8 on the k2. Similarly, 10 watts on external wattmeter is reading 6.9 on the k2 at an 2.8 amps. Cranking the rf power all the way clockwise shows 15 watts on k2 and hi pwr message (cal curr set to 3.25) and external wattmeter shows 19 watts. The RF detector seems to be reading low. Check the RF detector components on the RF board: R66, R67, R68, R69, D9. Make sure the resistors are the correct values and the diode is the correct type. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ___ 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 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
