[hpsdr] Help with Alex SWR

[n3evl]

Don - did you calibrate the watt meter via the setup form in PowerSDR - 
see HPSDR Setup, PA Settings, Watt Meter.  Calibration steps are 
presented on the form.

Pete, N3EVL


On 10/26/2013 10:42 AM, dlwaddel at netzero.net wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Help please!
>
> My Alex is reporting high SWR even though my external VSWR meter reports 1.0:1 VSWR into a dummy load.
>
> The history is that when trying to find why I lose 50% power on 6 meters when going through Alex, I discovered that I had wound T1 and T2 on the wrong core. I removed them and wound new T1 and T2 on the specified FT50-43 cores. Now Alex is reporting high SWR on all bands.
>
> Here are some specifics:
> 20 Meters
> Tune power level set to 50
> SWR in PowerSDR 1.7
> External meter SWR 1.0:1
> Jack J2 pin 2 reads 0.8 volts
> Jack J2 pin 3 reads 0.17 volts
> Forward power in PSDR 7 watts
> Forward power on external meter 50 watts
>
> 10 Meters
> Power level at 25
> SWR 47.7 in PSDR
> External meter SWR 1.0:1
> Jack J2 pin 2 0.4volts
> Jack J2 pin 3 0.4 volts
> Forward power in PSDR 3 watts
> Power on external meter 20 watts
>
> Before rewinding T1 and T2, high SWR was reported on 10 and 6 meters only. I had wound the originals on T50-10 cores. (Hey, they are both black.)
>
> T1 and T2 were wound with the same convention as other coils such that the leads are in the correct positions to mount on the board. I have inspected both numerous times and re-installed several times to make sure the problem isn't incorrect installation.
>
> Resistors appear to be correct values and the diodes are installed in the correct direction.
>
> The transmit seems to work fine on all bands into a dummy load with SWR protection turned off, except for losing about half the power on 6 meters and about 10 watts on 10 meters versus without Alex in the circuit.
>
> Don
> K3DLW
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