Re: {Collins} 51S-1 PTO Issues

OK on the 100 Ω, R-62…..maybe someone couldn’t read the color codes (???)


I’m fairly sure when a replacement PTO is changed out at an official depot, the red inspector markings are re-applied.


A #131 51S-1, would probably have been shipped with either a two tube PTO, or one that was modified with a cover plate over the 2nd tube location.

Unless of course, the 131 S/N isn’t correct.


Does yours have 6U8’s or 6EA8’s in it?


The fact that the PTO has a round emblem guarantees that it has been changed.

No big deal though, as almost all of the 51S-1’s I have restored had round emblem PTO’s regardless of their S/N.


A radio with a two tube PTO is rather rare.

Not necessarily desirable, but rare.


And yes, T-501 is potted so leave it in place and add a replacement below the chassis inside the PTO enclosure.

Haven’t had a chance to find the specs on it, but I’ll keep digging.


73, Charlie k3ICH




From: Thomas Hoyer [mailto:thoyer1@xxxxxxxxxxx] 
Sent: Monday, October 02, 2017 7:57 AM
To: pincon@xxxxxxxxx; collins@xxxxxxxxxxxxx
Subject: Re: {Collins} 51S-1 PTO Issues


Hi Charlie,  


That resistor is really a 100 ohm resistor - newer body style (tan in color)  brn - blk - brn and measures 102 ohms. Hack job installation also.....


The PTO is a single tube round emblem with an MCN of what appears to be 273 (kind of faded). Appears to be the original one to the unit as all of the wires, except the one for the 1k connection, still had their red marking on the solder joint.





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