[Hammarlund] HQ-170A mods?

[Craig Roberts]

Hiya Gurus -- and Happy New Year!

While re-tubing my "new" HQ-170 VHF I discovered that it has been equipped with an OA2 VR tube rather than the OB2 called for in my schematic. The OA2 tube seems to work okay. So, for that matter, does an OB2 (while glowing a very bright orange).  Underneath, I've noticed what appears to be a modification to the power supply circuitry (perhaps to accomodate the OA2 ?). Two additional diodes -- besides the stock pair -- have been added.  And then there's this gray "thing" down there. It's not the 3K 10W power resistor but it is near it and resembles a "cement" power resistor, too. It is small in diameter, somewhat long and cylindrical in shape. This thing is as mysterious to me as a 1920's grid leak (which looks like a fuse) was years ago.  

What is this device?  A choke?  (I don't have the radio with me here at work so I can't tell you exactly where this thing is in the circuit). The device is a bit scorched and cracked, which is why I'm worried about it.  If it need replacement, I have no idea what to replace it with (!).

Oh -- and is the OA2 conversion a documented mod?

Many thanks and 73,

Craig
W3CRR