FW: FW: FW: [Elecraft] Kit arrived...

2007-03-22 Thread Brett gazdzinski 
 
 
 Brett,
 
 I agree with Tom - that you should re-peak the bandpass 
 filters at low 
 power (1 to 2 watts)  It is easier to discern the peak at low 
 power and 
 there is lesser chance that the K2 power adjustment mechanism 
 will try 
 to compensate and confuse the response.

I tried that.
I did it at 1 watt, no real change.


 
 Be certain to observe the correct band order for doing the bandpass 
 filter alignment - for any band pair, you must adjust the inductors 
 first and then the trimmer caps.  Do 80 and 40 meters in any 
 order, but 
 align 30 before 20, 15 before 17, 10 before 12.  If you have 
 the K60XV 
 installed, 40 must be aligned before 60 meters.  160 and 80 share the 
 same inductors, so you may have to compromise a bit between them, but 
 that filter is broad and there is plenty of reserve drive on those 
 bands.  On 10 meters, you may find better coverage across the 28.0 to 
 28.8 MHz band if you do the alignment at 28400 kHz rather 
 than the 28200 
 mentioned in the manual. But if your main 10 meter interest 
 is CW, use 
 the 28.2 point.

I have been doing it that way (by the book).
I have no idea what is on what band, and when they are open.
I have been stuck on 80 and 40 meters weekend mornings for the last
15 years or so, I have checked out 20 and 15 meters at night with the K2
and there is nothing there, so I suppose they are more daytime bands?

 


 
 Since you said you have a 'scope, you will find it easier to 
 watch for 
 the peak on the scope trace than to wait until the digital display 
 settles down.  Just connect your 'scope's 10X probe across the dummy 
 load.  Connect directly to the dummy load with a short connection for 
 the best results.
 
 You will be able to see the RF voltage peak on the 'scope 
 easily.  You 
 are not trying for any specific voltage, just for the point 
 of the peak.
 If you do not use the 'scope, make the adjustments slowly to give the 
 digital display time to respond.
 
 After peaking the bandpass at low power, you can re-check the 
 max power 
 output if you have any real doubts about it.

I think I am real close to maximum I am going to get out of the rig
without changes, and I am fine with 10 watts or more on most
bands, 10 meters is about 8 watts, I might try removing one turn
from L21 and L22 as a test.


Thanks,
Brett
N2DTS
 
 73,
 Don W3FPR

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FW: FW: FW: [Elecraft] Kit arrived...

2007-03-21 Thread Brett gazdzinski 
 
Don,
Ok, but why always on the low side and not the hi side
of error?

2 to 3 watts out of 10 is 20% which is not that good,
and why only at the higher frequencies?
On 10 meters, it might say 12 watts out but only give 8
actual watts
I want to know why it rolls off at the higher frequencies,
that is, the built in meter reads higher than actual power.

I suppose I should also test the rig at 14 volts, just to see
what the power out is.
The manual states that all the measurements were done at 14 volts
and I have been doing them at 13.8 key up.
My supply is regulated, but not that regulated..

And I wonder what sets the efficiency, output power VS current
and voltage in. Would that mostly be T3?

Eventually I might want to tweak that!

You can likely tell I like playing with radios more than
actually operating them, that is why the shack is almost
all home brew

Well, maybe tonight I will do the spectrogram stuff!


Brett
N2DTS


 
 You may find some frequency dependency between 1N5711 diodes (I have 
 occasionally noticed that), but I do not consider it a 
 problem because 
 the power indication and control point are not more than a 
 few tenths of 
 a watt off at any point if all is normal.  Considering that most 
 wattmeter specs are in the range of 5% to 20% OF THE FULL 
 SCALE READING, 
 the diode detector in the K2 is actually more accurate than 
 most if the 
   load is 50 ohms resistive at the frequency of operation (measuring 
 with an ohmmeter is not suficient, resistance at DC is not 
 likely to be 
 equal to the resistance at RF).
 
 On your wattmeter accuracy, consider that even 5% of the 20 
 watt scale 
 can result in an error of 1 watt at any power level - and 
 even the Bird 
 wattmeter is only that good immediately after calibration - you must 
 expect such errors in your measuring equipment (check the 
 spec sheet and 
   verify the measurement by independent means if you really want 
 accuracy).  The Diode Detector is actually more accurate than most 
 wattmeters, but it must be used with a known good non-reactive load.
 
 
 73,
 Don W3FPR
 

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