New project on HHH - GDO Revisited (GDO-2)

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Re: New project on HHH - GDO Revisited (GDO-2)

Post by Admin on Wed Feb 15, 2017 10:30 pm

Now I have scanned my first calibrated dial and built the next coil.
The new coil (5 + 5 turns) covers 14Mhz to 35MHz.

I also used Photoshop for the dial drawing. I created a layer for the original scan template, then drew a new blank dial on layer 1.
Layer 2 is the 8-22MHz calibration.
I am working on layer 3 for 14 to 35MHz.

I also found that the meter I have used is perhaps a little over-sensitive, so I may have to place a resistor, perhaps 10K, in series with the meter movement. This will also minimise the effects of the adjustment pot on the oscillator frequency.

BR Harry - SM0VPO

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(Thanks to those who tried and couldn't make the QSO. Back on 14.200MHz Sundays from the 24th Sept.)
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New project on HHH - GDO Revisited (GDO-2)

Post by Admin on Wed Feb 15, 2017 5:25 pm

Hello all,
The project gives a good description about why I needed to update this project.
This weekend I could not sleep (stinking cold - had it for four weeks) so instead of lying in bed moaning and groaning, I decided to build a new GDO because the old one looks really crappy, and I use it for demonstrations in my courses.

The result is that two sleepless nights rewarded me with this project:

http://213.114.137.49/use/gdo2.htm

It really does look posh  Very Happy

The dial/scale is the same size as the meter display, and the LED and black plastic case make it look a lot more professional. I have only re-built one coil for it, but the coils from my old GDO work ok from 100kHz to 400MHz.

If you don't like to wind a tapped coil, then no problem, do not use the tap. Just put a 470 Ohm resistor between pins 2 and 3 on the coil socket.

Hope you enjoy the project.
Best regards from Harry Lythall

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(Thanks to those who tried and couldn't make the QSO. Back on 14.200MHz Sundays from the 24th Sept.)
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