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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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2nd Feb 2019, 9:45 pm | #21 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Radionic Regen
I noticed on the Mu metal CRT shields for the VCR97 CRT that they can acquire a permanent magnetic field. It was easy to see the beam deflection when the two halves are assembled around the neck, with the CRT running. So I simply used a degaussing wand on it (well away from the CRT of course). That appeared to solve the problem, but I guess I could have heated it too.
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2nd Feb 2019, 10:19 pm | #22 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Radionic Regen
Quote:
I wound my own butt stacked output choke. I had an 8R speaker, and the choke (autotransformer) was tapped to give an impedance ratio of 22:8. Also looking back at the circuit, the OC16's emitter current was 420mA, and I use a 3.3R emitter resistor dropping 1.38v. As I recall it could easily deliver 1.5 to 2W audio out which was plenty for a desk top radio. In a car they push it a bit harder to about 2.5W. The OC16 is mounted on a 1/8" copper flange which is also thermally coupled to the steel chassis (The paint was removed under it, and heat conducting compound used). I did thermal stability tests on it at the time and the heat sinking was perfectly adequate for our sometimes 40 Deg C ambient temps, if not over killed. I also incorporated NFB from the speaker connection to the cathode of the EF98 driver valve, simply by adding a 75R resistor in the cathode and a 560R resistor to the speaker terminal. Also as I recall, the input sensitivity is such that about 1V or 2V rms at the EF98 grid, attains full output, but I would have to check that. I could attach the schematic of the radio if it is any help. |
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2nd Feb 2019, 11:35 pm | #23 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Radionic Regen
Tim, what a wonderful piece of work!
Love it! What are the dimensions? It looks pretty expansive!
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Al |
3rd Feb 2019, 12:04 am | #24 |
Hexode
Join Date: Aug 2010
Location: Malvern, Worcestershire, UK.
Posts: 347
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Re: Radionic Regen
Argus25
Thanks for the detailed info,I am impressed by your hybrid build and remember that you gave detail of the driver transformer designed for the task.It was not clear to me what you had used after the Transistor,however. It is easy to find your posting on the forum therefore I appreciate your offer of a link but really have no personal need for it. I have been messing around with the American space charge range of Tubes and the European 12V valves but have not settled yet on a Superhet or a Synchrodyne format. Regards Mike |
3rd Feb 2019, 1:06 pm | #25 |
Triode
Join Date: Feb 2014
Location: London, UK.
Posts: 20
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Re: Radionic Regen
Hello Al
The Radionic Perspex panels are 12" by 9" perforated with 1/8 inch holes at 3/4 inch pitch. The radio uses 3 panels so overall it's 36" by 9" .
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Regards, Tim |