Saturday, December 12, 2009

HF radio (3)

Still "fighting" to put the DDS programing software accessing the parallel port under "dosemu", will try now to boot DOS native...if I can find a diskete....

--Adendum--- Found a diskette with DOS, saved dds software on it, changed to another computer, changed parallel port to standard, messed with the cables... and voilá! Programed with a fresh 9Mhz "IF" more or less some little herts...I am happy -- end adendum----

Meanwile made a new "rf test probe", smaller with a less drop diode... now I have more 0.1v on my measurings. Previous diode has a drop of around 0.40 this one has 0.30 more or less... but still I have to calibrate the dam thing. I measured my DVM internal impedance.... it almos reaches the 30MOhm... wich lead me to doubt on the metod used... so I made the probe assuming the impedance was 11MOhm.
You can see in greater detail the original design:

Meanwhile I had to move the shack power supply near the computer so I can program de DDS and found out that actually the power supply wasn't a laptop power supply inside a box,....I was almost sure it was..., after all it was a conventional power supply with an 7812... the other output is a varialbe LM317 type, no wonder that sometimes it shuts down with lot's of boards beeing connect.... oh well it was puttede in place an worked for so many years that I forgot completly.... the box is of "Chivas Regal" brand.... will rebuild in one of this days. The paper inside is the schematic... in case I forgot what was done....It was the case!

No comments: