RE: [Elecraft] Peculiar problem on 80 M
Steve, Have you perhaps increased the value of R98 on the bottom of the RF Board to give you a more stable power control at high power? If so, it will make the power control at lower power more sluggish. That is the only thing I can think of which would make a difference. There is nothing band dependent about the power control that I am aware of, but the overall gain of the transmitter does vary from band to band, and that combined with the granularity of the power control may be causing the effect. The K2 remembers the power setting unless the power request is changed or the band is changed. So the real power output that you are observing may be dependent on the exact steps that you are using to observe this phenonomon. You did say that you verify the power output level on the K2 display? Can you provide the sequence you are using to do that? The normal transmit display does not show the power output level, so you must be doing something other than a keydown. It would also be of interest to know if the same thing happens with the wider range QRP levels - power the K2 through the low power jack only (disconnect or turn off the power to the KPA100). 73, Don W3FPR -Original Message- I have a strange problem with my K2/100 on 80 meters. The situation is as follows: I work QRP DX at the low end of 80 M, (say 3508 kHz or thereabouts) with a requested power of 4.5 watts, and get an indicated 5 watts out. I then check into the Pine Tree Net on 3596 kHz and crank up the requested power to 10 watts (this is before the relay clicks; I'm still in QRP mode), and I get about 10 watts out. So far so good, right? Then I go back to 3508 kHz, without resetting the power request level knob, but the rig puts out 5 watts, even though the display acknowledges my ten watt request. If I go back to 3596 the output goes back to 10 watts in agreement with the requested level. Note the essential point, when I make a big excursion in frequency, the radio is putting out a level of power substantially different from the requested level. I can correct the output level at the low end by sweeping the requested level either low (near 0) or high enough to make the QRO relay click, and then adjust it down to and desired QRP level, and the rig will put out approximately the requested level of power. The phenomenon occurs whether I change frequency by switching VFOs preset to the two frequencies, or if I retune one VFO using the tuning knob. This is not an issue of varying antenna impedance. I get this effect with a commercial dry dummy load as well as a real (very well matched) antenna. I can also create the effect the other way around. If I request 5 watts at the 3596 then go to the low end and request 10 watts, then go back to 3596 with the knob in the 10 watt position, I still get 5 watts until I jigger the power level request knob. I have tried to reproduce this effect on 40 meters, requesting 5 and 10 watt levels at frequencies differing by about 100 kHz. In that case I get what I would regard as normal behavior. The rig always puts out the approximately the requested level of power irrespective of when I set the power level request knob. Has anyone else run into this phenomenon? Is it a quirk in the software? Is something wrong with the radio? 73, Steve Kercel AA4AK ___ 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.405 / Virus Database: 268.12.8/455 - Release Date: 9/22/2006 ___ 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] Peculiar problem on 80 M
Don: Thanks very much for your various suggestions. I have made no mods at all. R98 is the original value. I did not think that there was anything band dependent about the power level. That has led me to wonder if the problem might be a software glitch. The phenomenon does depend on exact steps, but is repeatable if I do those steps. I verify the level of requested power by tweaking the power knob very slightly. If I was at 10 watts and tweak it down a bit the display momentarily shows a numerical 9.5 watts. I can then tweak it back up and get the 10 watt reading. However, when the anomalous behavior is occurring the bar graph shows 4 or 5 watts on key down. Running the rig from the low power jack as a diagnostic is a good idea. However, I'll need to make up a new power supply lead before I try it. I've never used anything but the Anderson lead thus far. Thanks again, Steve At 07:28 AM 9/25/2006, Don Wilhelm wrote: Steve, Have you perhaps increased the value of R98 on the bottom of the RF Board to give you a more stable power control at high power? If so, it will make the power control at lower power more sluggish. That is the only thing I can think of which would make a difference. There is nothing band dependent about the power control that I am aware of, but the overall gain of the transmitter does vary from band to band, and that combined with the granularity of the power control may be causing the effect. The K2 remembers the power setting unless the power request is changed or the band is changed. So the real power output that you are observing may be dependent on the exact steps that you are using to observe this phenonomon. You did say that you verify the power output level on the K2 display? Can you provide the sequence you are using to do that? The normal transmit display does not show the power output level, so you must be doing something other than a keydown. It would also be of interest to know if the same thing happens with the wider range QRP levels - power the K2 through the low power jack only (disconnect or turn off the power to the KPA100). 73, Don W3FPR -Original Message- I have a strange problem with my K2/100 on 80 meters. The situation is as follows: I work QRP DX at the low end of 80 M, (say 3508 kHz or thereabouts) with a requested power of 4.5 watts, and get an indicated 5 watts out. I then check into the Pine Tree Net on 3596 kHz and crank up the requested power to 10 watts (this is before the relay clicks; I'm still in QRP mode), and I get about 10 watts out. So far so good, right? Then I go back to 3508 kHz, without resetting the power request level knob, but the rig puts out 5 watts, even though the display acknowledges my ten watt request. If I go back to 3596 the output goes back to 10 watts in agreement with the requested level. Note the essential point, when I make a big excursion in frequency, the radio is putting out a level of power substantially different from the requested level. I can correct the output level at the low end by sweeping the requested level either low (near 0) or high enough to make the QRO relay click, and then adjust it down to and desired QRP level, and the rig will put out approximately the requested level of power. The phenomenon occurs whether I change frequency by switching VFOs preset to the two frequencies, or if I retune one VFO using the tuning knob. This is not an issue of varying antenna impedance. I get this effect with a commercial dry dummy load as well as a real (very well matched) antenna. I can also create the effect the other way around. If I request 5 watts at the 3596 then go to the low end and request 10 watts, then go back to 3596 with the knob in the 10 watt position, I still get 5 watts until I jigger the power level request knob. I have tried to reproduce this effect on 40 meters, requesting 5 and 10 watt levels at frequencies differing by about 100 kHz. In that case I get what I would regard as normal behavior. The rig always puts out the approximately the requested level of power irrespective of when I set the power level request knob. Has anyone else run into this phenomenon? Is it a quirk in the software? Is something wrong with the radio? 73, Steve Kercel AA4AK ___ 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 -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.405 / Virus Database: 268.12.8/455 - Release Date: 9/22/2006 ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info
Re: [Elecraft] Peculiar problem on 80 M
Stephen W. Kercel AA4AK wrote: I have a strange problem with my K2/100 on 80 meters. The situation is as follows: I work QRP DX at the low end of 80 M, (say 3508 kHz or thereabouts) with a requested power of 4.5 watts, and get an indicated 5 watts out. I then check into the Pine Tree Net on 3596 kHz and crank up the requested power to 10 watts (this is before the relay clicks; I'm still in QRP mode), and I get about 10 watts out. So far so good, right? Then I go back to 3508 kHz, without resetting the power request level knob, but the rig puts out 5 watts, even though the display acknowledges my ten watt request. If I go back to 3596 the output goes back to 10 watts in agreement with the requested level. snip Has anyone else run into this phenomenon? - Steve, After checking I find that my K2/100 #3255 behaves in the same way on 80m when feeding a good dummy load. - do not have any 80m antenna. As you say the problem does not appear to arise on other bands. I notice other strange behaviour on 80m related to 'power request', but I would need to run various tests before making any comment. 73, Geoff GM4ESD ___ 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] Peculiar problem on 80 M
Fellow Elecrafters: I have a strange problem with my K2/100 on 80 meters. The situation is as follows: I work QRP DX at the low end of 80 M, (say 3508 kHz or thereabouts) with a requested power of 4.5 watts, and get an indicated 5 watts out. I then check into the Pine Tree Net on 3596 kHz and crank up the requested power to 10 watts (this is before the relay clicks; I'm still in QRP mode), and I get about 10 watts out. So far so good, right? Then I go back to 3508 kHz, without resetting the power request level knob, but the rig puts out 5 watts, even though the display acknowledges my ten watt request. If I go back to 3596 the output goes back to 10 watts in agreement with the requested level. I have seen similar power output glitches with my K2/100. See the link below. In one case, I was getting 160W output on 1.8MHz. This is really bad when you are driving an amp! Having the KPA100 doesn't matter though, the same effect occurs in the basic K2. I believe these issues are because the K2's TX agc doesn't have any memory about what drive level is needed on different bands, but always tries to correct in real time. The agc level for a given power output varies quite a bit on different bands. Changing frequencies rapidly appears to confuse the agc in some cases. In my case increasing the resistor in the agc (R98 if I remember) helped. see: http://www.ac6rm.net/mailarchive/html/elecraft-list/2006-07/msg00684.html Tor N4OGW ___ 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] Peculiar problem on 80 M
Elecrafters: The seemingly peculiar behavior that I have been observing on 80 M turns out to be normal for a K2. Gary at Elecraft sent me the following message. 73, Steve AA4AK This is just due to the bandpass filter rolloff and the way the ALC in the K2 works. If you test the rig in transmit by using the Tune button, the rig will be able to measure and set the RF level better. Some bands have more overall power gain than others. So it is often necessary to transmit for a short time with the Tune and Power knobs to ensure the desired RF output is being produced. An improvement in the ALC action and power control accuracy for a specific K2 can be had by doing the modifications shown here: http://www.elecraft.com/Apps/Power_Control_Mod.html -- 73, Gary AB7MY = [EMAIL PROTECTED] Elecraft Technical Support At 10:07 AM 9/25/2006, Geoffrey Mackenzie-Kennedy wrote: Stephen W. Kercel AA4AK wrote: I have a strange problem with my K2/100 on 80 meters. The situation is as follows: I work QRP DX at the low end of 80 M, (say 3508 kHz or thereabouts) with a requested power of 4.5 watts, and get an indicated 5 watts out. I then check into the Pine Tree Net on 3596 kHz and crank up the requested power to 10 watts (this is before the relay clicks; I'm still in QRP mode), and I get about 10 watts out. So far so good, right? Then I go back to 3508 kHz, without resetting the power request level knob, but the rig puts out 5 watts, even though the display acknowledges my ten watt request. If I go back to 3596 the output goes back to 10 watts in agreement with the requested level. snip Has anyone else run into this phenomenon? - Steve, After checking I find that my K2/100 #3255 behaves in the same way on 80m when feeding a good dummy load. - do not have any 80m antenna. As you say the problem does not appear to arise on other bands. I notice other strange behaviour on 80m related to 'power request', but I would need to run various tests before making any comment. 73, Geoff GM4ESD ___ 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
Re: Re: [Elecraft] Peculiar problem on 80 M
This is just due to the bandpass filter rolloff and the way the ALC in the K2 works. If you test the rig in transmit by using the Tune button, the rig will be able to measure and set the RF level better. Some bands have more overall power gain than others. So it is often necessary to transmit for a short time with the Tune and Power knobs to ensure the desired RF output is being produced. I do not understand the last sentence above. Does this imply that the alc works differently when Tune is pressed than when the key is closed? Tor N4OGW ___ 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
Fwd: AA4AK: RE: [Elecraft] Peculiar problem on 80 M
Tor: Does this answer your question? Steve AA4AK Delivered-To: [EMAIL PROTECTED] Delivered-To: alias-suscom_maine_net/[EMAIL PROTECTED] From: Gary Surrency [EMAIL PROTECTED] To: 'Stephen W. Kercel' [EMAIL PROTECTED] Cc: 'CSinfo' [EMAIL PROTECTED] Subject: AA4AK: RE: [Elecraft] Peculiar problem on 80 M Date: Mon, 25 Sep 2006 15:10:25 -0700 X-Mailer: Microsoft Outlook, Build 10.0.6626 X-pstn-levels: (S:99.9/99.9 R:95.9108 P:95.9108 M:97.0282 C:98.6951 ) X-pstn-settings: 3 (1.:1.) s gt3 gt2 gt1 r p m c X-pstn-addresses: from [EMAIL PROTECTED] [2583/111] It mostly boils down to the fact that the MCU does not sample the RF output when the rig is first turned on, a band or mode is changed, or the VFO is moved significantly. Only when the Power knob is moved, or the rig is placed in Tune mode, does the rig sense and adjust the RF output. The bandpass filter characteristics are such that the signal level from the filter do change across the upper and lower end of each band. -- 73, Gary AB7MY = [EMAIL PROTECTED] Elecraft Technical Support --- ___ 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
