poniedziałek, 5 września 2016

SX-28 further inspections

Some day had some spare time (why it happens so rarely... :)) and decided to have a closer look into the new SX-28 (new in my shack, it is nearly 70 years old and is probably the oldest thing in my home....)

Disassembling is not very difficult task - if you remember the weight around 20kg :)

Inside I found some work that needs to be done. 
The capacitors in the power supply look newer than 70 years but not sure. Were they blue in that time?

Transformers don't look new but luckily seem to work correctly.

Most of paper capacitors are wet and covered with oil.

Chassis is mostly in a very good condition - probably radio has been stored in dry and nice conditions.

Variable capacitors don't look too good. This is a problem because probably it will be difficult to find similarly mounted ones.

Elements are mounted in "3D" mode (not on PCB) - it will be very difficult to replace some elements. In the worst case I will have to dissasemble everything and build back using new elements.

Some potenciometers required cleaning.

VFO section from the top. Tubes belong to VFA, mixer and IF amplifiers.

I had some problems to find out how tuning works. Usually could not find a proper frequency. I have measured the VFO frequency and now I know how it works. In fact it is not as bad as I was afraid - I have to set the main dial to the "dot" on the scale and then the secondary dial shows more or less correct freq. Not bad...

Finally I have prepared list of elements I want to replace and slowly starting looking for them...

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