[Hallicrafters] HT 33A series

[John King]

Howdy knowledgeable Hallicrafters historians. I have googled the Hallicrafters HT 33 HT 33A and Hallicrafters HT 33B, and still have a question.

I have an HT 33A amplifier that I am refurbishing and think it will turn out beautiful. It has the Penta PL172 that is probably bad being at least 50 years old. 

I notice from Google that there was an HT 33 and then a HT 33 Mark 1 and then the HT 33A followed by the HT 33B. I think mine is a regular HT 33A because it has only four VR tubes I am in the process of trying to convert it to HT 33B by placing six voltage regulator tubes and changing some resistors.Question: Was the "Mark I" a version of the HT33 and before the HT 33A and HT 33B?

All I have left to do is to wire up the two additional voltage regulator tubes.  The instructions for the conversion instructs to "delete this connection on the HT 33A, it is already deleted on the Mark I series". That tells me that the Mark I series came after the HT 33A series and before the HT 33B.

As of now, I see the two 68K resistors the connection between is to be disconnected, but I don't see the connection that is to be disconnected. Those two resistors don't exist on the HT 33B schematic. They are replaced by one 100K 2 watt resistor to ground.

I think the problem is that I just can't see the forest for the trees. I just haven't located the connection the instructions mention. has anyone converted a HT 33A to a HT 33B?? If so, I would like to correspond with you via email> Thanks and 73, John, k5PGW "Old Geezer Radio"