SA602 and 604 Giveaway Update, and SA604 Circuits

I’ve had a busy few days. Since posting details of the reels of SMT SA602 and SA604 IC’s that a very generous ham sent to me with a request to distribute them to other homebrewers and building groups, I’ve been spending quite a lot of time cycling to and fro between my house, the local print and copy shop (for supplies of padded mailers), and the Post Office. The first day’s worth of envelopes looked like this just before being bundled into my backpack for the short trip to the Post Office (names and addresses inexpertly blurred out in order to protect the identities of the innocent) –

I mailed out 18 packets on the first day, and almost as many the next day. Most went to individual builders and experimenters, though a few did go to groups for group builds. The response has been very encouraging. I wasn’t too sure how many people would be interested in SMT parts but it seems that quite a few folk do indeed experiment and build with them – and they are not all young ‘uns either. One gentlemen who requested a set is 83 years old. Excellent! With the help of breakout boards, like W1REX’s MePADS, or these ones from OSH that Sanjay KI6VFH told me about (only $1.50 for 3, including shipping), once you’ve got the device mounted to the pad, building Manhattan-style with these IC’s is straightforward. Incidentally, the boards from OSH are SO-8, so will work for the 602’s but not the 604’s, which are SO-16. Also, Rex’s pads can be glued straight onto a copper substrate as there are no contacts on the flipside, while the OSH one will need to be suspended above the copper groundplane with short, stiff ground leads. Perhaps someone has posted a design for an SO-16 breakout board on OSH?

Standing in line at the Post Office has it’s good sides, one of them being the notices that I spotted attached to the plexiglass divider at the customer service counter –

As I thought would be the case, everyone wants the 602’s. I was expecting only a few people to also want 604’s but as it turns out, a majority are also asking for a few of them. Many don’t yet know what they will do with them but are hoping to find a worthy project. A few actually have projects planned. One gentleman is planning a group build with his club, in which they will build pagers. I didn’t ask for more details on what the frequency of operation will be, but I am curious. Another is going to build a weather satellite receiver.  Paul K0EET mentioned that 604’s turn up in home-brew spectrum analyzer projects as an IF strip and a logarithmic RSSI (to drive the y axis).  He also told me about an article in the July 1993 issue of QST by OH2GF for a synchronous AM detector using an SA604 and a couple of 602’s. It is designed for receivers with an IF of 450-455KHz, so would be a great addition to many existing shortwave receivers. Thanks Paul (makes mental note to remember this project). In it’s application as a Received Signal Strength Indicator (RSSI) it could also be used as an S-meter for a direct conversion receiver (a quick Google search should get you a circuit).

So quite a few circuit ideas for the SA604. The application sheet also shows how, with an SA602, you can make a simple FM receiver. Personally, I can see wanting to try it out as a synchronous detector for AM signals at some point.

Oh – one idea for the 602’s which I thought was very novel, was one gentleman who plans to rip out the guts of his HW-8 and replace them with a DDS-tuned superhet. Cool!

I started out with quite a large reel – bigger than shown in the picture of Sprat The QRP Cat performing QC. By the time I took that picture, several hundred had already gone out to various experimenters and builders. With the encouraging response to these posts, I will probably run out soon. Not to worry though, as the gentleman who sent them to me still has some left that he has promised to send. I am not sure when those will arrive, but I’ll post updates to this blog. I don’t think it will be very long.

If you build something cool with these chips, please let me know!

NOTE – SA602 and 604 offer on hold until further notice. I’m almost out, but the very kind gentleman from Oregon who sent me this batch has some more he will be sending soon. I will make a new post to this blog when I have more IC’s in stock.

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