Amp keying circuit K2
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Hi,
Just a quick question.. I've just installed the parts in my basic K2 to externally key an amp. I've just tried to key my old FL-2100B with this, but have found that as soon as I plug the cable in, the amp keys when the radio is still in RX ?? Is there a menu setting I need to change or have I made a mistake on the circuit ?? The cable is fine as I use this on my FT1000mp to key the same amp. I've checked the resistance on the keying circuit and I get about 18ohms, when the radio is keyed, as opposed to open circuit when in the RX state ?? Thanks David, VK2NU _______________________________________________ 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 |
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David,
No question is quick if you need to understand what is going on <G>! The amp keying circuit should work unless the output transistor is being forced into conduction from whatever voltage is being applied on its open collector - it should not be if the voltages applied are within a normal range. Without the amp connected, you can check the base voltage of the 2N2222 transistor - it should be very close 0 volts during receive and about 0.7 volts (the emitter/base junction voltage for the 2N2222) during transmit. If those two conditions are not true, then you have something wrong with the keying circuit wiring. During receive, the 2N2222 should be cutoff due to the low voltage at its base and should not conduct even with voltage applied to the collector. Be certain the resistance in the emitter path is quite low - a bit of resistance there could cause the output transistor to misbehave. If your problem still is not solved, try measuring the circuit output transistor voltages (to K2 ground) with the amp connected and the K2 in receive. The emitter should be zero volts, and the base should also be very low, while the collector should measure at the voltage applied externally from the amp. Be certain you have a good low resistance connection from the amp ground (terminal E) to the K2 ground and a good connection from the amps RY terminal to the keying circuit's output collector. If you find the conditions above are OK, you likely have a bad 2N2222. 73, Don W3FPR > -----Original Message----- > > Just a quick question.. > > I've just installed the parts in my basic K2 to externally key an > amp. I've > just tried to key my old FL-2100B with this, but have found that > as soon as > I plug the cable in, the amp keys when the radio is still in RX ?? > > Is there a menu setting I need to change or have I made a mistake on the > circuit ?? The cable is fine as I use this on my FT1000mp to key the same > amp. > > I've checked the resistance on the keying circuit and I get about 18ohms, > when the radio is keyed, as opposed to open circuit when in the > RX state ?? > > Thanks > > David, VK2NU > _______________________________________________ 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 |
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Hi All,
Thanks for all the responses to this - much appreciated. I'm afraid it was a simple case of me not reading the instructions on the keying circuit. The FL-2100B pulls 20v on its keying input, whilst the circuit for the K2 is only designed for 5-12v !! This is clearly written on the instructions with the circuit, which I neglected to read. Does anyone have details of a simple circuit I can build, so I can use this with my FL-2100B ?? Again, many thanks for the all the replies !! David, VK2NU -----Original Message----- From: Don Wilhelm [mailto:[hidden email]] Sent: Tuesday, 18 July 2006 2:58 AM To: David Douglass; [hidden email] Subject: RE: [Elecraft] Amp keying circuit K2 David, No question is quick if you need to understand what is going on <G>! The amp keying circuit should work unless the output transistor is being forced into conduction from whatever voltage is being applied on its open collector - it should not be if the voltages applied are within a normal range. Without the amp connected, you can check the base voltage of the 2N2222 transistor - it should be very close 0 volts during receive and about 0.7 volts (the emitter/base junction voltage for the 2N2222) during transmit. If those two conditions are not true, then you have something wrong with the keying circuit wiring. During receive, the 2N2222 should be cutoff due to the low voltage at its base and should not conduct even with voltage applied to the collector. Be certain the resistance in the emitter path is quite low - a bit of resistance there could cause the output transistor to misbehave. If your problem still is not solved, try measuring the circuit output transistor voltages (to K2 ground) with the amp connected and the K2 in receive. The emitter should be zero volts, and the base should also be very low, while the collector should measure at the voltage applied externally from the amp. Be certain you have a good low resistance connection from the amp ground (terminal E) to the K2 ground and a good connection from the amps RY terminal to the keying circuit's output collector. If you find the conditions above are OK, you likely have a bad 2N2222. 73, Don W3FPR > -----Original Message----- > > Just a quick question.. > > I've just installed the parts in my basic K2 to externally key an > amp. I've > just tried to key my old FL-2100B with this, but have found that > as soon as > I plug the cable in, the amp keys when the radio is still in RX ?? > > Is there a menu setting I need to change or have I made a mistake on the > circuit ?? The cable is fine as I use this on my FT1000mp to key the same > amp. > > I've checked the resistance on the keying circuit and I get about 18ohms, > when the radio is keyed, as opposed to open circuit when in the > RX state ?? > > Thanks > > David, VK2NU > -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.394 / Virus Database: 268.9.10/387 - Release Date: 12/07/2006 _______________________________________________ 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 |
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David,
Best solution: Change the output transistor to a mosfet device which will be capable of handling the higher voltage. See the .pdf from Tom Hammond's website - http://www.n0ss.net/k2_basic_8r_line_t-r_adapter.pdf for the re-designed output device (HEXFET). It will require changing one of the resistors in the present keying circuit as well as the output device. Another solution would be to use the present amp keying circuit (and a power supply) to key a relay - use the relay contacts to key the amp. Depending on the speed of the relays, that may slow things down a bit and you will cause problems with QSK keying. 73, Don W3FPR > -----Original Message----- > > Thanks for all the responses to this - much appreciated. > > I'm afraid it was a simple case of me not reading the instructions on the > keying circuit. > > The FL-2100B pulls 20v on its keying input, whilst the circuit > for the K2 is > only designed for 5-12v !! This is clearly written on the > instructions with > the circuit, which I neglected to read. > > Does anyone have details of a simple circuit I can build, so I > can use this > with my FL-2100B ?? > > Again, many thanks for the all the replies !! > > David, VK2NU > > _______________________________________________ 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 |
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I answered David and apparently did not click on "Reply All." A long time
ago using the Elecraft Keying Circuit, I simply replaced the 2N2222 keying transistor with a MPSA42 which can handle max 300V (Vce) at 100 mA. It worked fine with my SB-220 which has ~110V on the key line. 73, Ken K3IU -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Don Wilhelm Sent: Tuesday, July 18, 2006 9:57 AM To: David Douglass; [hidden email] Subject: RE: [Elecraft] Amp keying circuit K2 David, Best solution: Change the output transistor to a mosfet device which will be capable of handling the higher voltage. See the .pdf from Tom Hammond's website - http://www.n0ss.net/k2_basic_8r_line_t-r_adapter.pdf for the re-designed output device (HEXFET). It will require changing one of the resistors in the present keying circuit as well as the output device. Another solution would be to use the present amp keying circuit (and a power supply) to key a relay - use the relay contacts to key the amp. Depending on the speed of the relays, that may slow things down a bit and you will cause problems with QSK keying. 73, Don W3FPR > -----Original Message----- > > Thanks for all the responses to this - much appreciated. > > I'm afraid it was a simple case of me not reading the instructions on > the keying circuit. > > The FL-2100B pulls 20v on its keying input, whilst the circuit for the > K2 is only designed for 5-12v !! This is clearly written on the > instructions with the circuit, which I neglected to read. > > Does anyone have details of a simple circuit I can build, so I can use > this with my FL-2100B ?? > > Again, many thanks for the all the replies !! > > David, VK2NU > > _______________________________________________ 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 _______________________________________________ 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 |
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In reply to this post by Don Wilhelm-3
After a 4th july trip with my k2 upon keying it goes hi current, then
does a reset. At any power level, any mode, any band, finals not shorted, but get instantly hot when trying to go to transmit before it resets. Can't measure any transmit voltages , since it won't stay in xmit,. I notices trouble when powering up , as the dsp would not always turn on ,,,, but since there is no power out and hot outputs guess it's in the xmtr??? not the control.... is there a convenient way to isolate the issue??? since it shuts down when going into transmit ??? bill _______________________________________________ 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 |
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next clue : i pulled the outputs, which are not shorted and the set acts ok ,
that leads me to believe that I got a lowpass filter issue .... especially since I get almost dead short at the output of the finals/ input to the LP filters,, onward,,, bill >After a 4th july trip with my k2 upon keying it goes hi current, >then does a reset. > >At any power level, any mode, any band, > >finals not shorted, but get instantly hot when trying to go to >transmit before it resets. Can't measure any transmit voltages , >since it won't stay in xmit,. > >I notices trouble when powering up , as the dsp would not always turn on ,,,, >but since there is no power out and hot outputs guess it's in the >xmtr??? not the control.... > >is there a convenient way to isolate the issue??? since it shuts >down when going into transmit ??? > >bill > >_______________________________________________ >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 _______________________________________________ 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 |
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Bill,
If you look at the schematic, you should discover that the LPF area will indicate DC continuity to ground. The secondary winding of T4 connects the input of the LPF to ground for DC. Since the K2 was working before, you have only a single failure point - keeping that in mind while troubleshooting is usually helpful and may prevent you from 'fixing' things that are not broken. I would suggest that you check T3 and T4 carefully (particularly T4), even to the point of rewinding them - while you have T4 out, you could check the LPF for a short to ground if you are suspicious of that. 73, Don W3FPR > -----Original Message----- > > next clue : i pulled the outputs, which are not shorted and the > set acts ok , > that leads me to believe that I got a lowpass filter issue .... > especially since I get almost dead short at the output of the > finals/ input to the LP filters,, > > _______________________________________________ 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 |
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