FUNcube Dongle

Folks,

I now have received all the parts for over 500 dongles. In addition I am seeing a new assembler tomorrow who I believe will be able to help us.

Howard

There’s a poll over on the FUNcube Yahoo Group set up to identify the level of interest in the FCD so that we can see if we can gauge better the anticipated demand over the next few weeks and months.

Howard

Folks.

104 Dongles were originally sold in total. One unit was refunded after a buyer changed their mind a short time afterwards, so a total of 103 were sold net. That extra Dongle is now on eBay where you can bid on it, with all proceeds to AMSAT-UK.

At 20:00:00, I put 80 units on sale in an attempt to mitigate against Paypal’s overselling ‘feature’. This oversold as 87 units by 20:00:54. The first sale made was at 20:00:19 (the first I have seen in under 20s). Extrapolated, this makes a sale rate of 149 units/minute. The rate for the second batch was 150 units/minute.

At about 20:02 or so, I put a further 13 units on sale, which oversold as a further 17 units. The first sale was at 20:02:30 and the last was at 20:03:12.

Two buyers managed to get two units each.

Howard

…and,as a bonus, your name or callsign etched into the FUNcube satellite!

I had a punter change their mind a few minutes after the sale on Friday. Rather than putting into the next batch, I am making it available on eBay here.

Good luck with your bidding!

Howard

The new batch from the manufacturer took quite a bit of effort to make work. Here’s a taster of the kitchen lab where the work is done.

Starts with an overview of the equipment, at 4:25 I show how to replace a QFN chip, at 11:27 shows part of the checking out procedure.

Howard

Folks

Although I have 100 built boards from the manufacturer, I am only getting about a 40% yield out of the box. It took me over a day to figure out what was going wrong.

It turns out that about half the 1.5V low noise voltage regulators from the assembler are failing. These provide power for the tuner chip (two separate ones to reduce noise). To make matters worse, their failure mode is to throw the USB 5V directly onto the tuner chip, which itself promptly fails short circuit to ground.

So I spent quite some time figuring out what was going wrong. At first I thought it was shorts under the QFNs due to the secondary failure mode. Then after replacing the tuner chip, measuring no short, applying power, ***PING***, blown up another tuner chip, something else was wrong. Turns out to be about half of these regulators.

The marking on the regulators looks fine. Specific date/batch codes are not an indication of failure either.

As luck would have it, I can isolate the power to the tuner by removing five chip inductors, test for the failure, replace the offending regulator(s), replace the inductors and away we go. But I have to do this on *every* unit. I’ve now fixed twenty-six, and I estimate this to be another 1.5 days’ work.

Today’s chip graveyard

Howard

Folks
The next sale will be on Friday 14 January 2011 at 20:00 UTC.

Sorry, sold out again. We will let you know the next sale time.

Folks

David Barber has very helpfully taken time to provide a couple of guides for the FUNcube Dongle here.

Howard

Folks,

There are a lot of posts asking to be put onto a reserve list. There is no such list I’m afraid.

The reason is simple: the overhead for us right now would be very high. Imagine, let’s say, there were 100 individuals on a hypothetical list. Then we’d have to individually contact and chase up each one of those people and request payment, track receipts and collate the information. As you can imagine, that would be quite a job in itself. Some may suggest that that figure of 100 is rather on the low side.

An alternative would be to take payment up front. I am personally not keen on that, as it means that we would be holding potentially significant sums of other people’s money and be duty bound to those individuals. When we had a situation like the manufacturer failing to deliver a few weeks ago, what would we do then? Should we refund (another administration overhead)? Contact each individual (yet more overhead)?

I freely accept that we didn’t really anticipate the level of demand, and while I know the current process isn’t perfect (remember it works both ways, Paypal still oversold what I had in the last batch), a publicised sale date remains to us the most fair way of distributing these units.

In the meantime I really thank you all for your patience and support while we ramp up production, and let’s hope this next batch arriving in the next few days is up to scratch so we can order some more.

Howard

Folks

When building the FCDs, I found a few failure modes where it meant I had to go back and debug a few of the boards, and I thought I’d share them with you.

All of these are manufacturing failures and are individually tested for and resolved on every device before dispatch.

The target is of course 100% no defects in the manufacturing process because the cost in time of fixing bugs is expensive. Reality is often different though.

The most common fault is a 1nF cap cracking after the rework for the HPF, I assume from the thermal stress. This shows itself as decreased sensitivity particularly at the lower end of the spectrum either permanently or intermittently, and if it’s intermittent, flexing the board makes it come and go as the cracked cap makes and loses connection. I am aware of only one unit that went out with this intermittent fault in the first batch. I sent a replacement immediately.

I now throw away the original 1nF cap during the rework process and put a new one in. This failure mode is also tested for on all units by deliberately applying mechanical stress to each board.

The next most common failure mode is on the tuner chip where the image rejection isn’t particularly good, typically only 15dB or so. To fix this, I have to replace the tuner chip. This has happened three times in 118 units.

On one unit the PIC wouldn’t cold boot into SDR mode, only bootloader mode. You could force it into SDR mode by using the “Switch to application” button. I replaced the PIC, and it worked fine after this.

I had one shorted ceramic 2.2uF chip capacitor across one of the supply lines. There was a just visible hairline crack on the cap when viewed through the microscope. The first check I do when plugging in is to check nothing’s overheating with the thumb test. The USB port is current limited to 500mA and the regulators all cut out at 200mA.

There was one case where there was a PCB short across one of the supply lines from some residual copper, that took quite some time to figure out.

Howard