[Milsurplus] AN/ARC-21 or 65

[Jim Whartenby]

RayThe ARC-21 uses DC servo motor tuning.  There are no solid state devices, not even diodes, tubes are the only amplifiers used.  The upgrade to ARC-65 uses 400 cycle single phase power but I have yet to find out exactly where it is used.  Seems that it is easy for me to get lost following wires through several pages of schematics!  The only difference between the DY-50/ARC-21 and the DY-153/ARC-65, that I have noticed, is the addition of a 115v to 28v 400 cycle transformer drawing 0.3 amps during receive, transmitting and tuning.  My gut feeling is that it supplies negative grid bias to the 4CX250F tubes in the power amplifier.Jim

I wonder why people argue over the 10% of their differences and ignore the 90% they agree on?

-----Original Message-----
From: Ray Fantini <RAFANTINI at salisbury.edu>
To: milsurplus at mailman.qth.net <milsurplus at mailman.qth.net>
Sent: Tue, Nov 3, 2020 11:27 am
Subject: [Milsurplus] AN/ARC-21 or 65

 #yiv2021248826 #yiv2021248826 -- filtered {}#yiv2021248826 filtered {}#yiv2021248826 p.yiv2021248826MsoNormal, #yiv2021248826 li.yiv2021248826MsoNormal, #yiv2021248826 div.yiv2021248826MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:11.0pt;font-family:sans-serif;}#yiv2021248826 a:link, #yiv2021248826 span.yiv2021248826MsoHyperlink {color:#0563C1;text-decoration:underline;}#yiv2021248826 a:visited, #yiv2021248826 span.yiv2021248826MsoHyperlinkFollowed {color:#954F72;text-decoration:underline;}#yiv2021248826 span.yiv2021248826EmailStyle17 {font-family:sans-serif;color:windowtext;}#yiv2021248826 .yiv2021248826MsoChpDefault {font-family:sans-serif;}#yiv2021248826 filtered {}#yiv2021248826 div.yiv2021248826WordSection1 {}#yiv2021248826 Wow, a Trippel headed DY-50 Dyno assembly! Thought the ARC-21/65 was a three phase 120 volts 400 cycle set? Was there also a version that ran from DC? Think but may be wrong that the B-36 was the first strategic bomber designed from the ground up to use 120-volt 400 cycle distribution and somehow assumed the ARC-21 was built for use in that aircraft.    Ray F/KA3EKH    ______________________________________________________________
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