RE: [Elecraft] Tx current

[Don Wilhelm]

Art,

3.4 Amps is higher than should be expected (unless there is a KPA100
attached).  The receive current on my fully loaded (no KDSP2) is 0.44 amps
at 13 volts -  this is only 0.16 amp above a typical K2 with no options.  If
the normal transmit current with no options is 2.5 Amps or less, I would
expect the transmit current to increase by no more than the 0.44 amps -
still less than 3 Amps.

Normally the cause of high transmit current can be found in the Low Pass
Filter or possible with the winding of T4.  A common cause is failure to
count the turns on the toroids correctly (count the turns that pass through
the center of the core - counting the outside turns can result in being one
turn off).  Yes, the K2 will seem to work just fine for all other aspects.

You might ask your friend if he wound T4 for 'better efficiency at 5
watts' - if that is done, the transmit current will be reduced at 5 watts
and below, but if one tries to push it above 5 watts, the efficency
decreases (resulting in higher than normal transmit current).

73,
Don W3FPR

> -Original Message-
>
> I'm using a friend's K2. It runs about 3.4 amps transmit with dial lite
> on. Has all the options. This is over an amp more than the book allows,
> but with all those options is it about normal?
>
> The rig seems to work fine.
>
> 73, Art
> www.k6xt.com
>
>

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RE: [Elecraft] TX current on the Elecraft K2

[Don Wilhelm]

Stephen,

Yes, that current is too high - you should not get Hi-Cur warnings at max
power with CAL CUR set to 2.5 amps.

First thing to check is the Low Pass Filter - check the capacitors for
proper values and the toroids for the correct color core and proper number
of turns (count each turn as it passes through the center of the core,
otherwise you can end up 1 turn off).

If the Low pass filter is OK, then check the winding of T4.

If all seems well for each of the above items, build the RF Probe if you
haven't already and turn to Appendix E of the manual - on page 12 you will
find the steps for Transmitter Signal Tracing - follow those steps and find
the stage where the RF Voltage differs substantially from the indicated
expected voltages.

73,
Don W3FPR

> -Original Message-
>
> I could do with some advice. I am at Page 72 in the K2 MANUAL aligning
> the TX for 40 Meters.
>
> At 5 watts output the current drain is supposed to be 1.3-1.6 amps. The
> book says if it is *much* higher than this, or the Voltage drops more
> that 1 Volt I may have a problem with the TX, load or PSU.
>
> The figures I get are: -
>
> Tx Off...13.8 Volts 200ma
>
> Tx on...13.1 Volts 2.16 amps 5 watts out according to the K2 internal
> meter, 6.1 watts out according to Motorola R200D comms analyserwhich
> contains the dummy load...the PSU is a large Palstar 30 ampere gizmo
> thus oodles of spare umph.
>
> Setting the power at 10 watts I get the following.
>
> Tx on 13.0 volts,  - High Current warning then 2.44 amps 10 watts out
> according to the K2, 7.87 watts according to the R200D,
>
> the manual says "if the current is *much* higher than 2 amps see
> troubleshooting."
>
>

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