Re: Damaged my Si4734


Having read your email and Scott's reply - When I solder in new loop should I earth the AMI line. Before working in dry weather I normally Earth myself out - used to that after working on 10C and AXE telephone exchanges also Computers. I would normally remove the batteries but there I suppose there is still the 1 farad capacitor keeping the memory up. One change i was going to implement when I mount the frame to hold the ferrite rod on my 380 was to have a double switched 3.5mm jack socket with 40/44 litz wire going to the board then plug in the new  loop with 3.5mm jack plug. this was to enable connection of 4foot loop or maybe your balum idea. Should we earth out loop/ferrite rod before plugging in. I suppose your problem may had to do with the random movement of the solder before it came to rest but in this weather static is always a major problem. In telecommunications many faults come about (especially static type damage) subsequent to a technician visit.
Your experience has been a good warning - have all the parts on order to build the 300usb radio - will also use Gary's idea for mounting the 7.5 inch ferrite rod again with the switching 3.5mm jack socket. I will have to be careful while carry out the modifications.

From: Roy
To: ultralightdx@...
Sent: Thu, 28 January, 2010 6:53:01 AM
Subject: [ultralightdx] Re: Damaged my Si4734


Thank you Scott for your generous offer. I have sent you an email with my address.

Thank you Jim and Steve for your offers.  This has to be one of the best groups I have ever come across.

Scott you are absolutely correct about grounding the line before soldering. "An ounce of prevention" as they say. One gets very blasé and when you have gotten away without the correct precautions dozens of times, you feel bullet proof. I have also been caught out on hot dry days with static. It has been hot and dry here in Australia over the past week with temperatures over 100 degrees F most days.

It was truly amazing the arc that the 660 Litz wire coil produced on the 7.5" rod and with freshly charged 2650MA NiMH batteries providing current into less than an ohm. It looked and sounded like RF.

Cheers Roy.


--- In ultralightdx@ yahoogroups. com, "sdwillingham" wrote:
> Sorry to hear that Roy. I guess it might be a smart precaution to
> short AMI to ground while soldering the antenna in.
> Shoot me an email with your shipping address. I'm sure I can find
> a replacement part around the lab here.
> I don't think that a C40 part is likely to work in the G8/PL-3XX
> radios until Tecsun ships it. (And I have no clue if, or when that
> might be.) From playing with my PL-300, I believe it is using
> a firmware 'patch'. So, although the C40 firmware should be
> backwards compatible, the radio (which expects a B20) will try to
> download patch code during the power-up process. Unfortunately,
> patch code is specific to the exact firmware revision, so the
> likely result is program corruption and CRC errors.
> -Scott-
> --- In ultralightdx@ yahoogroups. com, "Roy" roy.dyball@ wrote:
> >
> >
> > 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 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.
> >

Yahoo!7: Catch-up on your favourite Channel 7 TV shows easily, legally, and for free at PLUS7. Check it out.

Join to automatically receive all group messages.