Re: [Elecraft] my K2 and its different frequencies.
This is the same problem I had, except I had around a 600Hz shift, and it took some time to sort out. The eventually problem was indeed the J310 at Q24. Here is an extract of my exchange with Gary Surrency: Right, its now Sunday evening and I've now found the fault. Not having to worry about CW filters probably helped to concentrate my mind, and I reasoned that the problem just had to be associated with the BFO. The fault eventually turned out to be a defective J310 FET at Q24. It was allowing a couple of volts to appear at its gate when in Tx mode which was sufficient to alter the bias on D37 and shift the BFO when transmitting. For reasons I don't understand (as I am not familiar with the way the firmware works) this also had an effect upon the audio response when in/out of CAL FIL. In any event, not having a J310 to hand I replaced it with a 2N3819 and all my problems disappeared! If all else fails, it may be worth looking at this. gl Trev G3ZYY In message [EMAIL PROTECTED], Carel, pc5m [EMAIL PROTECTED] writes -Original Message- From: Carel, pc5m [mailto:[EMAIL PROTECTED] Sent: Tuesday, August 23, 2005 1:25 AM To: '[EMAIL PROTECTED]' Subject: RE: [Elecraft] my K2 and its different frequencies. Could it be you have an issue with the 8V internal supply ? Maybe on transmit it is somewhere loaded too much so it will drop and the BFO will also change slightly ? You could measure at pin 8 of U11. Also you could verify that the signal called V_BFO is not changed between RX and TX. It can be measured on pin1 of RP6. Another possibility could be a faulty Q24 (J310 FET) used for setting the TX power, normally the impedance on the gate of this FET wouldn't change substancially if V_ALC is applied, but maybe it is defect ? If you adjust TX power is the BFO frequency also changing ? Gl, Carel, pc5m -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, August 23, 2005 12:31 AM To: elecraft@mailman.qth.net Subject: [Elecraft] my K2 and its different frequencies. Many thanks to all who answered, including those who helpfully suggested that I might be using RIT or XIT without knowing it. I just put a frequency counter on the BFO on my K2, and it changes about 70Hz when it goes from receive to transmit. Yeah, I know, there's not supposed to be any change, but I get a 70Hz CHANGE IN FREQUENCY BETWEEN RECEIVE AND TRANSMIT. Freq. counter is loosely coupled to the BFO. Any ideas? Merlin, W3ICT ___ 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 -- Trevor Day UKSMG #217 www.uksmg.org ___ 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] my K2 and its different frequencies.
Many thanks to all who answered, including those who helpfully suggested that I might be using RIT or XIT without knowing it. I just put a frequency counter on the BFO on my K2, and it changes about 70Hz when it goes from receive to transmit. Yeah, I know, there's not supposed to be any change, but I get a 70Hz CHANGE IN FREQUENCY BETWEEN RECEIVE AND TRANSMIT. Freq. counter is loosely coupled to the BFO. Any ideas? Merlin, W3ICT ___ 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] my K2 and its different frequencies.
Merlin, First, yes, be certain RIT and XIT are truly not active, then see if the VBFO signal changes voltage (be certain you are in SSB mode) when switching from transmit to receive - monitor control board U10 pin 14. If it does change, I would venture a guess that the firmware THINKS either RIT or XIT are active, and you need to find out why that condition exists (problem is likely with the DAC or firmware). You may want to turn the RTI/XIT control to its extreme positions to see if the frequency shift becomes worse - if it does, then you can conclude that the RIT/XIT is always active. If VBFO does not change, then the BFO should not be changing frequency, and the 'problem solving' will be to determine what is pulling the BFO when in transmit mode. My first guess here is something associated with D37 or Q24. As you can likely understand, we will have to have more details of what does work and what doesn't work to home in on the problem area. This is strange problem - I (and several others) have followed the K2 since its inception and this is the first time I have seen a report of the behavior you are describing. 73, Don W3FPR -Original Message- Many thanks to all who answered, including those who helpfully suggested that I might be using RIT or XIT without knowing it. I just put a frequency counter on the BFO on my K2, and it changes about 70Hz when it goes from receive to transmit. Yeah, I know, there's not supposed to be any change, but I get a 70Hz CHANGE IN FREQUENCY BETWEEN RECEIVE AND TRANSMIT. Freq. counter is loosely coupled to the BFO. Any ideas? -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.338 / Virus Database: 267.10.13/78 - Release Date: 8/19/2005 ___ 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] my K2 and its different frequencies.
-Original Message- From: Carel, pc5m [mailto:[EMAIL PROTECTED] Sent: Tuesday, August 23, 2005 1:25 AM To: '[EMAIL PROTECTED]' Subject: RE: [Elecraft] my K2 and its different frequencies. Could it be you have an issue with the 8V internal supply ? Maybe on transmit it is somewhere loaded too much so it will drop and the BFO will also change slightly ? You could measure at pin 8 of U11. Also you could verify that the signal called V_BFO is not changed between RX and TX. It can be measured on pin1 of RP6. Another possibility could be a faulty Q24 (J310 FET) used for setting the TX power, normally the impedance on the gate of this FET wouldn't change substancially if V_ALC is applied, but maybe it is defect ? If you adjust TX power is the BFO frequency also changing ? Gl, Carel, pc5m -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, August 23, 2005 12:31 AM To: elecraft@mailman.qth.net Subject: [Elecraft] my K2 and its different frequencies. Many thanks to all who answered, including those who helpfully suggested that I might be using RIT or XIT without knowing it. I just put a frequency counter on the BFO on my K2, and it changes about 70Hz when it goes from receive to transmit. Yeah, I know, there's not supposed to be any change, but I get a 70Hz CHANGE IN FREQUENCY BETWEEN RECEIVE AND TRANSMIT. Freq. counter is loosely coupled to the BFO. Any ideas? Merlin, W3ICT ___ 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
