Damaged my Si4734

Roy <roy.dyball@...>

Hi All

It had to happen after many multiple operations and hundreds of hours of software development with my old faithful G8 I have damaged my Si4734 chip. I was sure that this was going to happen in the dozens of times I made connections to the control lines. But no, a careless slip of a Loopstick wire brought me undone.

I was unsoldering one of the loopstick wires when the heat travelled so quickly up the 660 strand Litz wire that it burnt my finger. 660 Litz is really flexible and with a nice tinned end it is relatively heavy. It seemed to fall across the circuit board snapping and popping till it came to rest. A coil made from 660 Litz is very low resistance.

Smoke was coming from the SW switching FET. Luckily I have one of these and it was easy to replace. However the radio was deaf on AM with only a bit of noise right at the bottom of the band, FM worked fine. To make double sure I disconnected the switching diode thus eliminating the SW pre amp this did not help. I also checked the AC coupling capacitor

Connecting the radio to my software showed that on every station that the varactor was showing max count and capacitance (6143) so it is not tuning. I have a really small propane torch so it only took 30 seconds to remove the chip from the circuit board ready for the new one.

I figure this is a blessing in disguise as I really want to try out the Ver40 firmware. The trouble is that those suppliers who stock the chip only have Ver20 and with the stock numbers they have I don't think they will be stocking Ver40 for a while. Has anybody in the group seen a Si4734-C40 in their browsing for sale? I tried Mouser.com but they only have the V20. Their price is good for the V20, about $15.00 but they want $39.00 to ship an item 3mm square that is probably so light you cannot way it.

I cannot speak highly enough about the Si4734 chip; it is a sturdy well protected little chip. This was my fault so be careful when working with 660 Litz wire. Also if ever you remove the Si4734 from the circuit board go out of your way to put it some ware safe as I have already misplaced the old one. I had it on my bench and when I looked for it, it was gone. It cannot have gone far and should turn up.

Cheers Roy.


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