Hi Bruce,
It would be very interesting to see what the Z input is at the primary of T1 when the oscillator is stopped. Can you make this measurement with the BPF disconnected from T1? With the oscillator stopped there will still be one of the QSD switches made and thus one of the secondary windings will be loaded by 10 ohms in series with the switch resistance. This series combination should reflect to the primary by the square of the turns ratio, i.e, (13/6)squared. With the oscillator running there is still one switch and one 10 ohm resistor as a load on one of the secondary windings at a given time.
Thanks for all the work you are doing Bruce!
73,
Tony KB9YIG
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----- Original Message -----
From: "Bruce Beford" <bruce.beford@...>
To: <softrock40@...>
Sent: Saturday, October 08, 2005 4:47 PM
Subject: [softrock40] SoftRock Filter Sweep photos uploaded.
Hello everyone.
I have uploaded 4 new photos to the N1RX photo folder. These show
sweep results using an AmQRP Micro908 Antenna Analyzer on the
SoftRock. There are two pictures each for a SoftRock40 and for my
SoftRock80 prototype. For each unit, there is one photo for the
SoftRock under power, but with the local oscillator disabled. The
second photo for each, shows the same sweep, with the LO crystal
installed. Again, the Softrock is powered in all cases. Notice that
the local oscillator causes a big spike in the SWR curves at the LO
frequency, due to the oscillator energy that makes it out the antenna
jack. (Yes, the SoftRock DOES transmit, hi.) The SR80 graphs are from
2.5 Mhz-7.0 Mhz and the SR40 graphs are from 5.5 Mhz -14.0 Mhz. If
larger photos are desired, I can repost them to the files section
where they won't get squished down to only 400 pixels wide.
73, Bruce N1RX
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