[Elecraft] K2 power anomalies

[Julian, G4ILO]

Don,

Thanks for the input. If it's true that the DL1 is accurate, then I don't 
like the implications. Not only why has my K2 been putting out less than 6W 
on 10m for 3.0A current draw for the last 4 years, but why have all the 
other power indicators been over-reading the power at that frequency?

I'm afraid I continue to disbelieve the DL1. If I set the K2 for 10W out, 
two other external power meters all show around 9 - 10W regardless of band. 
Although they have only been calibrated by comparison with the output from 
a commercial transceiver, the built-in power indicators in the K2 (the 
original simple one, and the better one in the KAT2) have also all shown 
that my K2 is capable of generating more than 10W on all bands. 

Only the DL1 suggests that the power output falls off significantly on the 
higher frequencies. It has been suggested that my DMM is at fault, but 
since it is reading a DC voltage, I can't see why it's reading should be 
affected by the frequency the K2 is generating. If it is, then this is 
something that people using the DL1 as a tool to measure their power output 
need to be aware of, otherwise they could be tearing their radio apart for 
no reason.

73,
--
Julian, G4ILO. (RSGB, ARRL, G-QRP)
G4ILO's Shack: http://www.qsl.net/g4ilo





  ==== Original message ====

> Hi
> 
> I did some testing with my DL1 and I found it to be quite accurate. At 
> 7.100 mhz I get 15.7 volts with 10 watts in. This correlates with the 
> graph. Moving to 28.100 MHz I get the same reading at 10 watts in. I 
> connected the DL1 to a leveled RF generator and ran the frequency from 
> 50 KHz to 250 Mhz and the output was the same within about 20 mV across 
> the band. I used a WM-2 to measure the power out on the K2 and also 
> checked it with a precision attenuator fed into a 400 Mhz scope. The DL1 
> matched up perfectly with the other metering methods. I connected the 
> DL1 directly to the K2 BNC using the double male adapter I ordered  with 
> the DL1. When connecting the other meters I used a 6 inch BNC cable to 
> keep the connection as short as possible. 
> 
> You should not have any reason to question the DL1 from what I am 
> getting. I think the readings are really what your K2 is doing. Watt 
> meters are notoriously inaccurate. Even the WM-2, one of the best, falls 
> off about 10-15% at 10 meters. This is why I always used the precision 
> attenuator and the scope to set up the K2-K2/100 tuners or anything that 
> needs to be accurate. As simple as the DL1 is, it appears to be very 
> accurate. I would say it is a must have if you do not have any other way 
> to check the power out on a K2. It's inexpensive and simple. 
> 
> In fact I would recommend anyone thinking of building a K2 to order the 
> DL1, N-Gen and XG1 mini kits with the K2 and build them first. This will 
> give you the experience and confidence to build the K2 and you get 
> useful test equipment you will need to make setup and alignment easier 
> once the K2 is finished.
> 
> Don
> KD5NDB
>