I got, from a friend, a broken Redifon GR 345D with the matching 100 Watt linear GA 480.
Nothing is working. No Receiving, no Transmitting, not output from the linear.
I think he have it from the scrap yard.
Its was very hard to get the schematics from the GR 345, so I take the schematics from the PRC-74. I OM in UK help me with the manual.
The GR 345 have only 100mW output for the Linear. The Linear is internal switchable from 100mW in to 15W in.
After that the 100 mW comes out the transceiver by transmitting. But the frequency is not right. Only the MC Knob works, the rest not. So I changed there some transistors too.
After that I was happy and I hear a signal from the function generator 🙂
You can take for the BFX18 a BF199 and for the 2N697 a 2N1711 or a BFW67. It works 🙂
The 2N706 I got from eBay.
I changed near 30 parts in this radio and I worked near 40 hours on it.
Now I ordered a 1750 KHz LSB filter in the USA the replace the AM with LSB. The transceiver have only AM,CW and USB, what is not so nice for a frequency range from 2 up to 12 MHz.
The Linear GA 480:
The Linear is a lot of harder. I checked everything in this linear. It looks like OK. It must be the 100W module, was is broken.
This is the 100W Module
Normally its oil filled
I resistor was burned. I had no 4.7 Ohm resistor, so I take some together.
The finals are RCA 60282 transistors. In the manual it is no schematics from this module, only from the rest of the linear. Over this transistors you find nothing in the internet. In the manual is wrote: “If this module is broken, replace it with redifon part number xxx.
I see some finals in eBay what maybe can fit. It was some KT904, what was not so expensive. I insert this and I change the parts what I see, what is broken.
Then I use the function generator as a driver and I start to test it. It came with 50mW in 5 Watts out for a little time. After that it burns after some seconds 🙁
So my finals for 20€ was broken again. The finals must be the wrong types.
I see that one little transformer is broken. But without any informations over the transformer and the finals, it is not possible to repair.
So I take all usable parts from this module and start to build a MOS FET Linear Module for 100 Watts. This will take a while…
But my transceiver works and I can test it so far. Here is the video.