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  #1  
Old 12-22-2012, 11:11 AM
Geist Geist is offline
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Dumont 304 scopes

Hi All;
What is the difference between the Dumont 304-C and the Dumont 304-H ?? Where they like improvements -A, -B, -C etc.. Or did they stand for something such as -C, Commercial, -H, Heavy Duty, etc..
THANK YOU Marty
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Old 12-22-2012, 12:12 PM
bob91343 bob91343 is offline
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Scratching the head for old memories, I seem to recall that the entire series was pretty much identical. Mostly cosmetic differences, like the 401 vs the 401A, which simply had changed from inch calibrations to centimeter. I have owned several of these and don't recall any real differences. Maybe the H had higher sensitivity but I'm treading on thin ground here. Bandwidth on the entire series was about 100 kHz oops I mean 100 kc. I may still have some manuals.
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Old 02-15-2014, 08:04 AM
bigbob bigbob is offline
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Hi!
I realize this is an old thread but I wondered if I could tap your knowledge. I'm looking for a manual for a Dumont 401A. Would you still have one? Second, I saw info, online, where Fairchild took over Dumont. Would you happen to know if the Fairchild 401A is the same as the Dumont 401A?
Thanks for any info.
Bob
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Old 02-15-2014, 05:01 PM
bob91343 bob91343 is offline
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I think I still have Dumont 401/401A manuals. I used to own a 401R.

There were two versions, one with 'Sola' type power supply and the other with electronically regulated supply.
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Old 02-15-2014, 10:10 PM
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Einar72 Einar72 is offline
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If anyone ever finds a manual for Dumont scope type 250-AH, I'd love to have a copy...
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Old 02-16-2014, 10:39 AM
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N2IXK N2IXK is offline
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I believe the "H" stood for "high brightness" or "high intensity", as it had an additional high voltage supply for the post-deflection accelerator.

The schematic here:

http://bama.edebris.com/manuals/dumont/304

shows the differences between the 304 and the 304H. The additional circuitry used in the 304H is shown in a dotted line area in the power supply. The note near the CRT intensifier connection describes the difference in the circuit.
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