The cabinet was ordered from Qrp Project in Berlin http://www.qrp-shop.biz/epages/qrp-shop.sf/de_DE/?ObjectPath=/Shops/qrp-shop/Products/Kuehlr168x110x54 It fits the board like a glove . For smooth tuning a 1:10 ball drive is added. Because of the 180 degree tuning range of the polyvaricon, only a 1:5 reduction remains. Ball drive reductors:
A series 3000 Multiplex RC transmitter was the donor for the tilt stand, but US builders can find one here :http://www.budwig.com/collapsible-tilt-stands.html
The latest boards have a litle bug causing a shortcut to ground of C37 and R22 .This prevents the noisefilter from doing his job. Before installing C37, take a 4mm drill and make a smal cone in the board surface to remove the ground connection .
I noticed that the noise filter even causes the noise levell to rise , so i desided to remove C37 and R22 permanently.
More info about this nice kit : http://ea3gcy.blogspot.nl/
Today i installed the Iler DDS generator. I expected some digital noise but surprisingly the audio stayed verry clean after a small mod. without any spurs or birdies. I kept the old counter for this made the DDS unit smaller and easyer to mount. At trials the new counter was only atached for the DDS setup in the generator mode , from 10.000 - 10.350 MHz without IF ofset . The IF ofset is already programmed in the Hendricks counter. Once the DDS was programmed the bleu Iler counter was removed.
Tuning is verry smooth and accurate with the provided step levells.
Next mod wil be a simple NE 555 tone generator to generate a carrier for swr readings.
POPPING AUDIO MOD.
Despite of a reasonably good working lf AGC, verry strong signals can produce a loud popping sound due to a massive overload of the LM-386 input. 2 Bat-85 Skottky diodes in anti-parallel over the 10K-B volume potentiometer and a 10K resistor between C32 and the potentiometer cure most of the problem.
The extra parts can be mounted directly on to the potentiometer.
DDS POWER MOD
The DDS adds some noise to the audio. A small 100uH choke and a capacitor to ground at the DDS power pin are the solution
|Iler base station 20m. 70 Watt|