REPAIR AND RESTORATION OF THE SR-400
2
WDØGOF 6/22/20014
INTRODUCTION
This is not a “restore to museum” quality guide. Cleaning, painting and front panel touchup are not covered.
There are reams of documents that cover those actions. There are very few documents that delve into the inner
workings of these radios. This does. This document applies only to the Cyclone II and Cyclone III. The first
question you might ask is “why did I not include the SR-400 Cyclone”? The first generation 400 had too many
things not quite correct. Mr. Orwin (Hallicrafters engineer) fixed those when he designed the Cyclone II. The
best advice I can offer to owners of the original SR-400 is to upgrade it to the Cyclone II level. A document for
upgrading a Cyclone to the Cyclone II is available. Contact me and I will send you the document. Just to clear
the air I am not a fan of the Cyclone III either. I use my Cyclone II. I turn on my Cyclone III once a month for 2
or 3 hours just to keep it dry.
This document takes a systematic approach to rehab. Unless otherwise noted all discussions apply to either the
Cyclone II or III. It is designed to be used in conjunction with the original equipment manual. In all discussions
the word
manual
refers to:
OPERATING AND
SERVICE INSTRUCTIONS
FOR
COMMUNICATIONS
TRANSCEIVER
MODEL SR-400(X)
If this procedure is followed, in the order presented, you will minimize the frustration of restarts and backups
and chasing red herrings. It assumes a working knowledge of radio and tube circuit theory. For the most part it
will lead you to the stage or stages where faults have occurred. At this point you must have the skills to locate
the failed component. Each step of this process assumes all proceeding steps have been successfully completed.
If you try to jump into the middle of the process you may end up in confusion.
You have obviously elected to spend time and effort in this restoration.
So, I highly recommend
that you
do a dry run with the schematic, manual and this document. As you read this document follow it through the
schematic and the manual. A wealth of knowledge will be gained by doing so.
This document is the intellectual property of the author, Walter A. Cates, WDØGOF, unless specifically
credited to a contributor. All processes, ideas, drawings, data sheets and opinions contained here-in are
the intellectual property of the author. Any reproduction of this document for profit will be vigorously
pursued.
CAUTION: FATAL VOLTAGES ARE OPEN AND EXPOSED ONCE
THE COVERS OR CASE IS REMOVED. OBSERVE THE FREE
HAND RULE. THAT IS, ANY TIME THE POWER IS APPLIED, IF
YOU ARE RIGHT HANDED YOUR LEFT HAND IS IN YOUR HIP
POCKET. IF YOU ARE LEFT HANDED YOUR RIGHT HAND IS
IN YOUR HIP POCKET. YOU PROCEED AT YOUR OWN RISK.
