Whats an acorn tube? These little
tubes were developed in the WW2 era for VHF use. Small glass
envelope with pins sticking out radially. In my project I'm using
the 955 triode as a regenerative detector (at shortwave freqs)
followed by two stages of audio amplification with a 6SN7.
In my search to do something a little different I ran across an article on the web using one of these tubes and shaped that plan to fit my approach. John, WA4WDL, set me up with a few 955's and a nice socket.
This shows the inset mount for the 6SN7 so as to not have it extending too far out of the front panel.
Here you see the ceramic acorn
socket. The goal here is 3 bands of shortwave and taps will be
selected by trial and error. If I goof up the coil too much I'll
rewind it after I'm finished experimenting. Its hard to see but
the tickler winding is a few turns interwoven at the top end of the
coil. Thats also trial and error. Hopefully I can get a
single tickler to work on all 3 bands, 3-18 MHz.
I splurged on a sheet of brass for my projects. A 12x24 sheet is only $11. I've been wasting good PCB for my ground shields. Why 1-watt carbon resistors? Because I have lots of them!
I splurged on a sheet of brass for my projects. A 12x24 sheet is only $11. I've been wasting good PCB for my ground shields. Why 1-watt carbon resistors? Because I have lots of them!
Heres the front. The two tubes will stick out of the panel and since they are 6.3v filament tubes they should show some neat light. The little power supply will go inside the set to provide 135 vdc and 6vac.
Mockup, with dust. The audio jacks and volume control are on the lower sub-panel. Regen throttle cap and bandswitch are on the main panel.
Interior mockup, all ready to go but not wired together. Only lacking the interstage xfmr at the moment.
Go to Page Two
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