Hamfest stuff

[Richard Hull]

The Berryville hamfest is the biggest hamfest this year in Virginia since the Richmond hamfest in Feb 2020. About 600-700 people attended at the Berryville fair grounds. I picked up some goodies, as usual images below. I spent about $110 in total $40 of that was for food and gas.

First image is of my Surface mount soldering win. My 7 watt pencil iron was not doing well and so I got a complete kit from a fellow telling me this is the ideal surface mount kit. It includes a bit more powerful soldering iron and some special solder he said was perfect for electronic repair. Got this rig inexpensively. The power cord looked a bit iffy, but he assured me, ("tis but a mere scratch, sir") He noted that you just don't see cords like this anymore and the tufting gave the cord "character" and that it was old school and had many years left in it and was "sound as a bell". He noted that the two prong AC plug made the iron completely isolated and totally free of any possible ground loop currents to the delicate surface mount ICs. He carefully explained "them darned three prong plugs is dangerous". "When I get something with that 3 prong plug, I cut that third prong off so they will fit the outlets in my old farm house up th' road a piece."................... Make sure to click on and enlarge this image.

The second photo is of 2 of four Simpson LED in-panel voltmeters picked up at a buck a pop and they all work great. Also in the image is one of 4 rack and pinion slides also in the dollar each box. For another dollar I picked up the really nice, working Thermo, nuclear, negative bias supply adjustable from -400V to -2500 volts. Thermo bought out just about every nuclear instrument maker of old, if you will remember.

The last image is a complete Canberra model 40 multichannel analyzer, gamma spectrometer. I paid $20 for it. It seems to have an odor problem. I turned it on and an odor of burning resistor came out of the muffin fan grillwork.

This makes Canberra model 40 number 3 here at my house. The first is my 100% functional model in the upstairs lab. Bill Kolb gave me his model when it malfunctioned to monkey with and now this hamfest buy. I hope to get one of them working using parts from one or the other.

I did not see one living being at the fest with a mask on. I was looking for them too.

Richard Hull

[Dennis P Brown]

Wow, really a great haul but the Canberra model 40 multichannel analyzer for $20 is an absolute steal and a piece of gold considering what you need it for! That is, having a parts source for such a useful but obsolete instrument is beyond valuable especially since you already have a working one to cross check issues against and plan on using this unit to make another 'non-functioning' unit work. Great idea.

That variable supply is really nice - the range is really impressive; never seen such a PS with that versatility. Good eye on catching that one.

Those giant soldiering irons do have some important uses and I have, on more than one occasion, wished I had one for a soldiering job - really amusing about the three plug issue; not totally wrong (relative to ground loops, through I really doubt that he has such super delicate IC electronic devices that that type of issue can be a problem) but certainly funny. It took me a few years to update all my two prong outlets to three over the years (and correct labeling on the breaker panel which was a good lesson about assuming ... ) - a pre-60's house has its draw backs.

Considering how Delta is cutting through the country filling hospital ICU's wards, I'd think a few would have had masks - oh well.

[Richard Hull]

Yes, stuff was plentiful and cheap at the fest. I really took advantage of the one dollar boxes often found at the hamfests and the low price "silent key" tables. There was an amazing amount of DCC, enameled wire on old wood spools at the fest. I thought I had bought all of it left on earth in the 80's! If I didn't have so much in the lab, I would have snapped it up. Again generational death bring out treasures in cycles one of the great advantages of hamfesting. What was once treasured, like clean and a restored "Atwater-Kent" that sold for hundreds in the 70s and 80s can now be had for under $100. I bought an ancient RCA Radiola 18 for 20 bucks two years ago. A pile of lap tops with Win 96 installed with "Office" and working were $20 each with no takers. Another pile of early "think pads" free..... The cycles come and go.

Panel meters (analog d'Arsonval) are especially good deals. I scored big, finding two NOS 5" Weston meters, in box, for $3.00 each! What was amazing is the FS-5ua movements!!! I knew of 20ua meter movements and have a few on hand in the lab.......But 5ua!!! I verified it upon getting back to the lab. The jeweled movement must be wound with 80 gauge wire.

How many of my gems will be left to others on my passing? The old gal asks frequently...."what am I going to do with all your crap when you are gone!", (assuming I'll go first...probably right, too). I tell her get on fusor.net announce one last giant sell off HEAS conference spread over one full week. "everything must go, no marked prices, make offer".......And there will be those 2 5ua meters for anyone offering a buck each or a buck for both. Oh well one man's treasure in soon to be another man's treasure. The cycle will continue until it all will wind up in a 2118 landfill with no one knowing what any of it is or was.

Richard Hull

[John Futter]

Richard
you will need a stereo microscope to use the uber fine tip on that SMT iron you bought, otherwise you might bridge the odd pcb track

[Dennis P Brown]

Well, I expect we at Fusur.net have MANY years before anyone gets to bid on the vast array of goodies you have amassed over the years! As for most the post, I have no idea of what most the items you mentioned really are. Still, Ham Fests are really amazing places but not just for the deals - certainly meeting and talking to fellow scroungers has to be more than half the fun.

[Richard Hull]

The guy said I could get the fine tips needed off the internet. No luck so far. Could it be the half inch shank? I looked up the Champion soldering iron company. They may be out of business. I also googled "tips for 250 watt soldering irons". Most of the tips were, "don't buy or use these for electronics." I think I might have been had by the guy at the hamfest. That's $3.00 down the drain.

Richard Hull

[Rex Allers]

@John Futter and the soldering iron tip

Ha ha! Enjoyed that.

High caliber weapons have their place. Perhaps this one not for most electronic work. The bluntness of this dum-dum seems a tad excessive. Maybe a coarse rasp, milling machine, or shaper could taper the tip a bit to look more like most of these big bruts I've seen. Tasks with sheet metal and solder joints come to mind.

When you want a sudden deep reservoir of pretty hot, something like this might be just the ticket.

[Richard Hull]

I actually collect these monsters as no one wants them and they are found and priced just slightly above free. Sheet metal work is indeed their specialty. Some are often used in the stained glass hobby on really big window projects. When the heat's on, these babies are what you want.

Richard Hull

[Richard Hester]

My father had one of those pump-up blow torches that ran off of white gas - just the thing for tamped lead/oakum joints on cast iron pipe.

[Richard Hester]

My Dad also had a mondo electric iron like Richards new acquisition. My monster iron is only 60W ( a Weller), but still useful for sheet metal.

[Richard Hull]

After many hours roaming through circuitry, I have fixed the $20.00 Canberra 40 gamma ray spectrometer! Several tantalums and two 100uh chokes the size of 1/8W resistors, created all the smoke pouring out of the fan port Several solder joints on the CPU board brought up the CRT and I checked it with a pulser to make sure the channel ADC was operational. In addition, 100% of all the range switches had their shafts seized. That was a nightmare of WD-40 soaking and wicking-in over 3 days!

I supply an image of my second, now fixed, "backup" Canberra 40. I still have Bill Kolb's inoperative Canberra 40, my third, to look at.

Richard Hull

[John Futter]

I knew that new soldering iron would be put to use!!

[Richard Hester]

For some reason, designers in the 70's and 80"s slathered their creations in epoxy-coated "teardrop" tantalums. That decision has caused people trying to resurrect these instruments many tears, as the tantalums will randomly short, pulling down local power supplies, sometimes blowing regulators and causing other collateral damage. Best to make a clean sweep and boot out all the tantalum caps, replacing them with modern electrolytic caps. Finding the damaged tantalums can be a problem, as the short often causes only pinpoint damage on the outer epoxy coating. Once you replace the lunched tantalum, the instrument is a ticking time bomb waiting for the next tantalum to blow. Sometimes it happens at the very next power-on after replacing the failed cap...

[Richard Hull]

Richard hit the nail on the head. Nim bins were prone to this issue and the designers knew it, placing a 4.7ohm 1/8W resistor in series with the power input on every voltage input line within their module.
When a tantalum went bad, (shorted), the resistor would burnup as a fuse. This alerted the technician to the buss in the module with a faulty tantalum cap.

Apparently, Canberra did the same thing but with HF quenching in mind. In place of the resistor they placed a 100uh choke with hair fine wire in series with the power buss. This forces anyone repairing their cards to cast about for a 1/8w resistor sized choke, (not an easy task today). Even surface mount stuff is not that small and would not fit in the CPU card's cramped space. I used a surface mount choke with leads attached soldered to the old holes and floating above the circuit board.

Richard Hull

[Dennis P Brown]

Richard, fantastic idea (floating a small circuit board above an existing one to replace an inoperative component too small to allow an available replacement - I have an identical issue that I gave up on for that very reason; how I have the solution; can't believe I never thought of that simple solution but that is what makes these forums so essential. Not everyone has the experience and wisdom generated by years of finding solutions to oddball problems.

[Richard Hull]

I have seen many model 40s with those two lines, top and bottom, burned into the phosphor. All of mine are free of this malady. As many may know, gamma spec work can require tens of hours or even hundreds of hours to complete a spectrogram with a corresponding background subtraction period. Blessedly, Canberra includes a handy intensity control on the lower left of the keyboard panel. When leaving this beast alone to do its long collection period, I always turn the intensity control to not illuminate the screen all the way down. (CCW)

I generally never use a collection time of more than 2000 seconds. Most of the time this is to just identify an unknown isotope from a weakly active source or an item suspected of being radioactive that a GM counter doesn't respond to, as in the case of a nearly pure gamma emitter or weak beta source. Trinitite easily reveals americium and Cs137 in this short period. Europium and other vanishingly small fission isotopes demand count times over many hours to reveal the tiny bumps in the spectrum. Actually, Trinitite is best looked at with an HPGE detector. The PMT falls on its face here.

I attach one of Bill Kolb's 5" PMT spectrums, (PDF file), of trinitite taken over a 10 hour period as the tube loomed close over a large sample of hundreds of pieces of Trinitite weighing 550 grams. This combination of mass and PMT crystal size did show europium. Bill is a master at squeezing the last bit from a PMT gamma spectrum from a weak source. Note: the bottom greenish spectrum was taken from Bill's spectrum techniques europium source for reference.

Richard Hull