2009-01-25
January Trash and Treasure
Peter VK2TPM and I headed up to Dural to attend the first ARNSW Trash and Treasure for the year. The turn out was quite good, the parking lot almost full when we arrived.
Quite typical of late the first thing you see on arrival is the huge pile of free junque from the ever faithful car-boot sale gentleman. The same pile of junk is always there, but it changes enough each time to make the scavenger hunt never boring. I picked up a pair of CRT tubes for small B&W TVs. I have one of these TVs, in a tape+radio+TV unit I got from Tandy years ago. Rumour has it that this pile of junk has its roots in the DSE and Tandy repair stock, so I probably have a spare if that thing ever dies. The tubes are branded Samsung, type 5KNB4 which I can't seem to find data on - darn! Unfortunately they don't have yokes, so using them will be even tougher.
Also dominating initial impressions was the new shed being constructed on site. After a protracted battle to get permission, the project is finally going ahead. The slab has been poured and the walls are assembled ready to be lifted into place by a crane early next week.
Silly me forgot my sun glasses, phone and cash! But Peter was kind enough to loan me a fiver so I could partake of the other great bargains available. In particular Mark VK2XOF had a box of 4-screw silver plated BNC panel-mount connectors still attached to phenolic insulators all with a short pigtail of RG-174. I bought the whole box and included in it was the back panel of a Fairlight video device of some description, filled with lower-quality but still quite usable BNC sockets and an optical position sensor from a tape transport mechanism. Dismantling the Fairlight panel would actually have been a good exercise for the talk Mark gave us later; recovering components from old equipment. My desoldering pump made easy work of the job to disconnect them from the backing PCB, but the threads of the connectors had been lacquered which made unscrewing them a bit of grunt work. All up it took probably an hour to recover a sandwitch bag full of perfectly usable connectors - I'm set for a while.
I also picked up an old Karaoke set which has a very similar if not identical B&W display in it to the free CRT tubes. The HT supply and yoke assembly (which still work, despite the unit missing its CD player assembly) should be handy in getting those CRTs going - when (if) I get around to it...
The traditional sausage-sizzle lunch was popular as usual, and talk amongst the various groups proceeded. John VK2ASU showed me his 3-transistor high-gain headphone amplifier that I had expressed interest in on our last radio net. It looks quite interesting, I'll have to get the circuit from him. He also showed his Hula-Hoop HF tuned RX antenna which has a JFET buffer.
Show and Tell was next. Despite almost forgetting to bring myself, I did bring my Inductor Saturation Tester, the Elektor FM Super-Regen Receiver and the Emitter Follower Regen. I passed them around for all to take a look at. Peter VK2EMU showed us a 17 metre vertical he plans to try some digital comms work with.
Kevin VK2ZKB showed us a helical antenna he put together for a mate's 800 MHz cellular data link. He passed around the design equations from the ARRL antenna book (same equations as my helical antenna calculator) and screenshots of the web-based interface of the cellular data modem device, including its RSSI indicator.
Graham VK2GRA showed us some nice wood-working he had done, a box in Olive Drab for his 10 and 6 metre vertical antennas (converted Station Master antennas).
Mark VK2XOF then finished up the day with a detailed and pragmatic lecture on recycling components from PCBs. Tools right up to the propane torch were included, a rather aggressive method that I myself have resorted to in the past. His mention of a solder pot has renewed my interest in building one myself, I've been meaning to do it for a while now. I think a solder pot would be quite useful, especially for tinning magnet wire on toroids and making up leads.
Peter's write-up of the day is also online.
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