Leon Heller wrote:
"andreas magun" wrote in message
Thanks for your reply,

I have checked the output power (voltage) from my quadrature driver
with a 50 Ohm load. The output voltage dropped by a factor 2,
indicating a good match. The same happened when I attached the
mixers (SBL-1) instead. I assumed that the LO-input resistance of an
SBL-1 at 7 MHz is close to 50 Ohm and purely resistive.

If there is not a plausible explanation for my results I will redo
the measurements, to exclude measuring errors.

Andreas


...

Hi,

I have assembled a T2 phasing exciter (KK7B) and looked
at its output spectrum with a spectrum analyzer.

When pumping the exciter with quadrature sine wave signals it
works as expected (output power roughly 3 mW, sideband supression
better than 40 db).

However, when pumping with quadrature squarewave
signals of approximately the same power, the output power
drops by a factor of at least 20 db! I would have expected
much more power, similar to that obtained with sine wave pumping.

The quadrature phase signal was generated with a 74F74, the
quadrature signals being attenuated to give a power of approx. 10 dbm and
output impedances of approx. 50 Ohms.


Have you checked the RF power from your quadrature driver with resistive
loads? It can be very misleading if you measure it whilst connected to the
mixers.

Leon