3CX3000A7 Removal

[BobOnTheJob]

I've heard stories of engineers using a block of wood & a piece of metal (screw? rod?) placed under a 3CX3000A7 in a CCA transmitter to 'push' the tube up out of it's socket. Playing with the concept, I used a 2' long 1" x 2" piece of wood & the 'non-bit' end of a 1" wood hole drill bit and the concept actually worked (at least in a CCA 3000D). I've been removing the blocker for decades at tube swap time. What I've done is pretty crude...wondered if I could collect input from others who may have perfected this technique? I want to make up something a little more refined...

 

[stephend2]

I just changed one in a newer cca, was able to push up with a small pry bar on the socket , gently I might add and work it out without removing the blocker. newer sockets are much more of a pain, this one has been through a few tube changes, doesnt hold on quite as well as it did when new.

 

[rfburns]

I've always removed the plate blocker so it could be inspected for problems and cleaned. Plus you can get a better look at the tube socket for any issues. It takes a bit longer, but I have found it is usually worth it.

RFB

 

[K4WRF]

I've heard stories of engineers using a block of wood & a piece of metal (screw? rod?) placed under a 3CX3000A7 in a CCA transmitter to 'push' the tube up out of it's socket. Playing with the concept, I used a 2' long 1" x 2" piece of wood & the 'non-bit' end of a 1" wood hole drill bit and the concept actually worked (at least in a CCA 3000D). I've been removing the blocker for decades at tube swap time. What I've done is pretty crude...wondered if I could collect input from others who may have perfected this technique? I want to make up something a little more refined...

I recall that at one time CCA had a special tool to extract the tube. In essence, it was a modified "wheel" puller that lifted the tube by the anode handles using an all-thread rod. That blocking capacitor if not properly manufactured or over heated would sometimes separate through the dielectric. The PA tube insertion tool of choice was the 2X4 out the front of the transmitter. I don't think the 3CX15000's were as difficult as the 3000's. Who makes those blocking capacitors now?

 

[LA_Guy]

We made a tube removal tool for our FM 20000. We drilled a hole on the screen that covers the chimney and bent a rack panel so it had fingers that hooked over the handles of the tube. There was a long threaded rod that connected to the center of the finger thingie and also through the hole in the screen and also through a piece of metal with a hole that went over the chimney itself. By using a wrench on a nut that went on the end of the rod, you could slowly pull the tube out of its socket. It worked very well.

 

[Lazy J]

Ha ha ha, I'm glad to know it's not just me. I have a 12kW CCA and I've always had a miserable time changing the tube. I just end up pulling the plate blocker too. WHAT A PAIN! bad design IMHO.

 

[BobOnTheJob]

Thanks for the input...last night was the acid test of this technique. The 1x2 and upside down drill bit had to be used several times from all 4 of the holes in the socket bottom along with a little lateral nudging from the top, but when it broke free, the old tube popped right out. Only tip I'd add is to make sure that the new tube is centered into the socket before applying the 2x4 (actually Watt, all I had was a 1x4)...once it was lined up, in she went. Actually, the 3CX3000A7 was the easy part. Getting the 3CX800A7 IPA in the socket proved to be the bigger time consumer.