[hpsdr] Help with Alex SWR

[dlwaddel at netzero.net]

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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