No power out on K1
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I've nearly completed my K1, and the receiver has been calibrated and
works extremely well. While calibrating the receiver against my K2, I had a 3 foot antenna consisting of daisy-chained alligator clips attached to the antenna jack, and I was picking up not only the adjacent K2, but also RTTY signals on the band! Sadly, the transmitter has not been so kind. Any attempt to put the unit in transmit mode (by pushing WPM+ and WPM- together) resets the power out to 0.1 watts, which is confirmed by the external wattmeter. All of the resistance checks on p45 have passed with the KFL1-4 removed and the jumper set to K1 (not KAT1). With the KFL1-4 in place and 14.38V at the input jack, a few of the voltage test points on p46 indicate 0.1-0.2V above the quoted range, which is presumably a result of the input voltage being a little higher than recommended. (I can stick a diode in the power cord if this is a real problem.) However, J7 pin 1 shows 7.8V instead of the quoted range of 5.1-6.7V. What, if anything, does this indicate? R9, D14, and D5 are all connected as measured by the ohm-meter. I've looked at the schematic, and I don't understand the RF-out path well enough to see what the obvious culprits might be. I have the RF probe that I built with the K2 plus a Tek scope. Any suggestions before I dive into the transmitter signal tracing on page 6 of Appendix E? A few pointers would be helpful before I disappear into the deep water! Cathy N5WVR _______________________________________________ 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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Cathy wrote:
>I've nearly completed my K1, and the receiver has been calibrated and >works extremely well.... > >Sadly, the transmitter has not been so kind. Any attempt to put the >unit in transmit mode (by pushing WPM+ and WPM- together) resets the >power out to 0.1 watts, which is confirmed by the external wattmeter. Cathy, By "resets the power out to 0.1 watts" do you mean that when you perform the steps on page 19 of the KFL1-4 manual to "Put the K1 into TUNE mode. Adjust C5, C6, CE ..." that you see P0.1 in the LCD? If so, then probably everything is OK and normal, at this point in tuning the KFL1-4. In TUNE mode, the LCD displays actual power output, and *not* the 2.0 value that you *set* as the power output limit on page 46 of the K1 manual. Until you make further critical adjustments to the filter board capacitors, you may indeed have very little actual power output, so P0.1 indicated after going into TUNE mode would be very likely. Verify that the power output limit is set to 2.0 per page 46 (K1 manual), then perform the step on page 19 (KFL1-4 manual) to put the K1 into TUNE mode. Then adjust those caps that were specified a little. You will likely find very sharp increases in actual power output indication (both on the LCD and your external wattmeter) as you find the best peak settings for the caps. Even if you had these caps seemingly well-peaked for receive mode, that only gets you just barely into the ballpark. Their actual required settings are very very much more critical for transmit mode. Be off just a little, and you'll still receive well, but transmit almost nothing. 73, Mike / KK5F K1 #175 _______________________________________________ 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 Cathy James
Cathy,
Definitions first - RF IN and RF OUT are designation of the RF Bandpass filter only - on transmmit the signal goes in as RF IN and comes out as RF OUT - however, on receive the path through the RF Bandpass is reversed, so 'in' is 'out' and and 'out' is 'in' <G>. Since you have a scope, I suggest you use it for peaking the Premix Bandpass filters and the RF Bandpass filters on transmit. Just read the RF Voltage - no exotic 'scope functions here - start with all the trimmers set near mid-position - put the probe on Filter Board P1 pin 6 while adjusting the Premix filters and simply adjust for maximum RF voltage on the 'scope. If you have the 4 band board, follow the band adjustment order - 30 meters before 40 and 15 (17) meters before 20 meters. If you have adjusted the trimmers for a peak on receive, you should not have to move the setting very far. Once you have the Premix Bandpass filters set, then do the RF Bandpass in the same manner - put the 'scope probe on P2 pin 8 and adjust for maximum RF voltage. After adjusting the filters for maximum RF voltage, you can try other things, trusting that the filter board is adjusted properly. Actually there is little more to be adjusted that will change the power output. You may need a bit of 'finger training' to enter TUNE without changing the power output level. Once in TUNE, you can tap one button to raise the power and the other to lower it. I cannot say where the extra voltage at J1 pin 1 is originating at the moment - it may be coming from the output of U9 - check U9 pin 6 to see how the voltage there compares with the voltage at J7 pin 1. 73, Don W3FPR > -----Original Message----- > ... > Sadly, the transmitter has not been so kind. Any attempt to put the > unit in transmit mode (by pushing WPM+ and WPM- together) resets the > power out to 0.1 watts, which is confirmed by the external wattmeter. > > All of the resistance checks on p45 have passed with the KFL1-4 removed > and the jumper set to K1 (not KAT1). With the KFL1-4 in place and > 14.38V at the input jack, a few of the voltage test points on p46 > indicate 0.1-0.2V above the quoted range, which is presumably a result > of the input voltage being a little higher than recommended. (I can > stick a diode in the power cord if this is a real problem.) > > However, J7 pin 1 shows 7.8V instead of the quoted range of 5.1-6.7V. > What, if anything, does this indicate? R9, D14, and D5 are all > connected as measured by the ohm-meter. > > I've looked at the schematic, and I don't understand the RF-out path > well enough to see what the obvious culprits might be. I have the RF > probe that I built with the K2 plus a Tek scope. Any suggestions before > I dive into the transmitter signal tracing on page 6 of Appendix E? > > A few pointers would be helpful before I disappear into the deep water! > > Cathy > N5WVR > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.441 / Virus Database: 268.17.39/686 - Release Date: 2/14/2007 7:54 AM _______________________________________________ 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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