As you know, my special interest is to buildt as much as possible on my own. For example:

I learned on building PAs with my 4CX-PA. The most important things to have a clear signal witch the maximum of output power is  the sreen grid supply. And also the driving grid has to be 100% constant. I will give you soon some layouts and i wanna try to offer  also ready to work boards for screen bias grid supplys. More is coming soon.
Click here to check my 1KW project with 2x4CX250 (in German)

  +++++ This is the actually chematic of my grid bias supply. I use simple BU208 transistors, connected in darlington function. Useable for 1 ore 2 tubes. Let me know, if you`re interested, i`ll send you the chematic! +++++

  +++++ This is the actually chematic of my screen grid supply. I use BU426 transistors, two of them connected in darlington function. Useable for 1 ore 2 tubes. Let me know, if you`re interested, i`ll send you the chematic! +++++

  +++++ This is the actually chematic of measuring g1 and g2 current with one meter including switching between the tubes, if used. Let me know, if you`re interested, i`ll send you the chematic! +++++

You`re are using the GI7b-tube for 2m or 70cm? I made my own experiences on this kind of triode. It`s a obviously a very cheap tube. But remember: it depends on the design of the cavity, but more than round about 300W clear-signal-output is not possible! OK, with more drive power for example you will see 500W on your PWR-meter, but it is not constant. After a few seconds of a RX periode you`ll see: you start TX with 200W or something like this. It is not a problem of to less air cooling. It is the tube itself! The grid inside the tube was original buildt for radar puls transmission and NOT FOR LINEAR MODES!

As you can see on the sites before i buildt all my yagi antennas on my own. It`s so easy if you have not two left hands, hi. I prefer the design of DJ9BV. Together with Nico DK5DQ we need only a half day to build four 10Elements yagis, each with al length o 4,4m. And they do their job fantastically. But if you`re rich enough, you can by some M2-Antennas, you`ll have the same effect. I hope to give you on this site some reliable sourses to get the material to buildt it on your own.

I build a special socket for GS-35b tubes. Look at the picture for mechanical drawings. Maybe if the interest is high enough, i will produce again some sockets.