My New TMC GPT-750 Transmitter

[W1ATR]

750 mills Steve. The one in my rig is an 8-15Hy swinger. Some models of this rig came with a 10-25hy swinger however. The caps are 3 paralleled 4mf/4000v bricks.

The whole point, which was sorrily missed, about the rectifiers was to just get the 872a power supply killers out of there. Of course I would like to run big diodes in there as well, but the proper devices are hard to find. Surplus thieves, oops, I meant to say "Sales" of Nevada had a run of them a while back and he wanted an arm/leg for them. These are the black stackable diodes shaped like a HV insulator that you can screw together with a base and cap, and drop them into the socket. I don't remember right now what the exact ratings were on them, but I know you had to stack at least 2 of them on each side, (3 would be better) and they were $25 each. (4pcs altogether) Add $50ea for two jumbo 4 pin adapter bases, and $15ea for two caps and you were at $280 with 3 diodes in each rectifier. The hell with that. I can shoot 4b32's out of a potato gun off my back porch all day long and not spend that much. They average $5-$10 each on ePay and they far out-rate the solid state way discussed above. They have a 10kV PIV, forward avg anode cur is 1.25A and peak is 5A. Now solid stating can be had by a group of diodes on a circuit board stuffed down into the socket, sure, but I'm not comfortable with half-assed, js'd hackery like that in a tx'er like this. (Junkston? sure, but not in this rig) Maybe a couple of those bricks sold by that ham who's call I can't remember right now would be cool, then just pull the tubes, sockets and fil tranny all together.

The way it was explained to me, the failure mode on an XG rectifier is that it just stops conducting, vs. the crazy flashover (and associated destruction) of a merc. Is this true, I don't know. I've never killed a 4B32 to find out. I have two of them in a 4x1 slopbucket amp (4200 on the plate) right next to me that get almost daily abuse and they're still plugging along just fine.

[W2PFY]

The whole point, which was sorrily missed, about the rectifiers was to just get the 872a power supply killers out of there.

I didn't know there was a point missed? Your right about the 872's and ancient  potted transformers. I only had one 4B32 fail. This is my only experience with just one of them. What happened is that the voltage gradually declined in a full wave circuit. Some 4B32 are designed to be able to view the glow and others are not. I have often wondered why they were built that way. 

[W1ATR]

I didn't know there was a point missed? Your right about the 872's and ancient  potted transformers. I only had one 4B32 fail. This is my only experience with just one of them. What happened is that the voltage gradually declined in a full wave circuit. Some 4B32 are designed to be able to view the glow and others are not. I have often wondered why they were built that way. 

I guess I didn't really mean that to sound harsh. My point was more about the 4b32's vs solid state blocks. In these big tx'ers, there so much avail room that there's no reason to go out of your way to use ss diodes and alter everything original, vs just plopping a couple of easy to find and cheap 4b32's in the sockets and calling it a day.