A 144MHz and 432MHz GS35b High Power Amplifier

(C) DL4MEA 03/1998

26.03.1998    added PPF description
21.07.1998    Weinheim Script added
06.10.1998    Preliminary English Version added
13.01.1999    PDFs moved to QSL.NET only

Full view:

A presentation of this amplifier and the 70cm twin was hold on the 1998 Weinheim meeting. I am very sorry for the bad quality of the pictures in the proceedings, in fact, I gave them raster printed pictures and thought, that their publishing studio would be able to handle them (as mine does). So here you can find a version where the picutures will print on your printer much better:
Script of  my Weinheim '98 presentation in PDF format (1,6 MB)

NEW!!! I am currently translating all into english language. Find a previous released version here for laugthing about my english and helping me to correct it. REMEMBER: The english is neiter re-read nor any other corrections done. Since I prepared this WEB page for linking to several files, some of the higher number parts may be missing as long as my document is not long enougth. Each part is always around 2MB.

Description GS35b PA 144MHz & 432MHz Pages   1-10
Description GS35b PA 144MHz & 432MHz Pages 11-20
Description GS35b PA 144MHz & 432MHz Pages 21-30
Description GS35b PA 144MHz & 432MHz Pages 31-40

(This is the version that will be printed in the Weinheim '98 compilation of scripts. It's in german language. I am planning to complete the description also in english. But there are a lot of pictures included into the text and it should give you an overview on what I made with the amp.)

Here are the cabinet drawings of the resonator and podest:
Backside + Bottom 
Front + Both Side Walls 

All bent parts already include the lips needed to screw them together.
The Top Cover is not displayed here, since it is just a rectangular sheet.
All parts were bent from 1.5mm thick aluminium.

And here, a don´t for excessive RF field surroundings:

After I had some HV flash overs at the tune capacitor, I glued some teflon sheet between both plates using strong adhesive grey tape. While operating, the arc overs were gone, but there was a smell of burned material. After I opened the cavety again, I saw that the tape become brown, it burned down under the heavy RF field which exists at the border of the capacitor plate.

(Just right click on the photos to see them in full size)


The original description of the 8877 amplifier, that I used as a basis of that project, is on W5UN's homepage: W6PO 144MHz power amplifier

I would be glad on any response to the amp. Now I am working at the document and can answer all questions that raise in it.

Datasheet of the GS35b

Background photo courtesy of CT1DMK