Text 22142, 297 rader
Skriven 2006-01-12 11:01:47 av Roy Witt (1:1/22)
Kommentar till text 21887 av Michiel van der Vlist (2:280/5555)
Ärende: Welding, brazing and soldering
======================================
11 Jan 06 10:10, Michiel van der Vlist wrote to Roy Witt:
>>>> OK, I'll give you that one. We call that type of welding, with
>>>> a torch, using filler rod (here they're about 3ft long).
MvdV>>> here they are 1 metre long. Thickness 3 or 4 mm.
>> Yeup. 36 inches equals 3ft, 1m = 39 inches.
MvdV> 36 inches is too short for most of the elements for a 2 m. beam.
Yeup. But it's plenty long for a 220MHz or 440MHz beam...Most of what I
worked when I built the Quagis was 440...
MvdV> One meter is long enough except for the reflector. That should be
MvdV> 104 cm. I silver soldered an extra 4 cm to that rod. I used a pice
MvdV> taken from the last director.
Maybe long enough, but the diameter doesn't suit the frequency. You could
use shorter elements by increasing the diameter. I used 3/8in (10mm)
aluminum to build a pair of 3 element beams for the 2mtr repeater I was
custodian of for a while.
MvdV> That was a 10 over 10. I later converted it to a 10 el cross yagi.
Back in the 60s, I built a 10mtr 4 element beam like this, only it had
elements spaced at 120 degrees about the boom.
l
/ \ It worked like the cross yagi, but I think it had better gain. At
least, I was never told the signal was any less than any other 4 element
beams it competed with and it was easily switchable from horizontal to
vertical polarization, fed with two lengths of RG8 coax. A HAM friend of
mine called the antenna a Gizmotchi and together we built several more.
I still find parts in my junk boxes for them.
>> The thickness is the same, 1/8th to 5/32 of an inch, which
>> equals 3 to 4mm.
MvdV> Close enough.
Yeup.
>> In contrast, the wire used in a wire fed MIG welder is about 1mm,
MvdV> Yes, I have sen them but never used them myself.
MvdV>>> The ones used for brazing are excellent for making an HB9CV fox
MvdV>>> hunting antenne. I made many of them. I also used the steel
MvdV>>> filler rod to make antennas but they are no good for permanent
MvdV>>> use at they will rust.
>> You can prevent rust by spraying them with a clear coat paint.
MvdV> For a fox hunting antenne that would probably ok. For a full sized
MvdV> antenna used for transmitting I would not use paint on the
MvdV> elements. Paint has very bad hf properties, it will absorb some of
MvdV> your transmitter power. So I used brass rods for the 10 over 10.
I've built yagis commercially and find that there is very little noticable
loss from using that paint. I've got beams in the garage that have spent
over 10years in the elements with no signs of corrosion. I'll take the
longevity over the loss of a few milliwatts anyday.
>> It's non lead based, so the antenna won't know it's been painted.
MvdV> It does not have to be conducting to absorb rf energy.
Neither do trees...yet we tolerate them in our RF lives.
>> I made a stacked pair of Quagi's out of brazing rod. It too will
>> corrode, so I sprayed it with clear paint and they lasted a
>> long time. I used PVC pipe to make the boom
MvdV> I used 5/8 steel pipe.
These were UHF antennas, thus the use of PVC. Cheap and easy to work with
at those frequencies. One the antenna I describe above, I used 1 1/4"
steel Electrical Conduit for a boom, which actually measures 1 1/2" in
diameter. And 3/4" diameter tapered to 1/2" diameter elements.
MvdV> The type that they used for electric conduits before PVC came into
MvdV> use. I drilled holes in it for the brass elements en soldered them
MvdV> to the boom with tin. I painted the boom, not the elements.
Nice thing about PVC pipe is that you don't need to solder, just use a
little bit of silicon rubber as glue.
>> and that will deteriorate in the sun. Which is why they
>> don't exist today.
MvdV> Right. Also PVC is not strong enough for a 10 el beam.
Not at 2mtr, unless you use an epoxy/foam filler.
>> I should put a photo of those on a website sometime.
MvdV> If you get the opportunity, please do. I can't show ypu a picture
MvdV> of my 10 el. I dismantled it some time ago.
I have one of the Quagi and one of the Gizmotchie in an album...I'll have
to scan them into digital format one of these days.
MvdV>>> We once made a dozen for the local scout group here to
MvdV>>> have fox hunt during a JOTA.
>> Alright.
MvdV> For those I used steel rod. It's cheaper and they were meant to be
MvdV> used only occasionally.
MvdV>>> So much for history. I have been lending my callsign to the local
MvdV>>> scout group for the JOTA for some twenty years now. This year,
MvdV>>> well last year actually, just before I was going to call them to
MvdV>>> remind them of the need to register, they called me to tell me
MvdV>>> that this time they would dispense with the JOTA part and do
MvdV>>> participate in the JOTI only. <sigh>
>> Time marches on.
MvdV> It does. Sometimes I don't like where it is going. This was one of
MvdV> them. But thereality is that ham radio is on the decline. It is not
MvdV> going as fast as FidoNet, but it definitely is on the decline. We
MvdV> have very little influx form the younger generation here. There are
MvdV> so many other interesting toys for which they do not have to go
MvdV> trough the effort of getting a license for. :-(
That's true, plus in the US, there is Part 15 of the FCC rules that allow
them to experiment with low power RF, so there's no longer a need to have
a HAM license.
>> I once led a club I was a member of in Poway, CA on Field Day.
>> Our score surpassed all the years before me and we did it
>> two years in a row. Then, the club got tired of doing Field Day.
MvdV> Local club stopped doing field days as well here...
Looking around these parts, I don't see any HAM antennas. There probably
isn't any club either.
>> I then became the repeater custodian until they got tired of
>> maintaining it.
MvdV> I was the custodian for the local 2 meter repeater PY3PYR for over
MvdV> ten years. Then another group wanted to build a new repeater and so
MvdV> I let go. I was tired of it anyway...
I lent my call to the repeater and it had an audio ID'er, which said my
call and also ID'd the repeater as belonging to the PARC...Poway Amateur
Radio Club.
>> It was then that I realized their interests and mine didn't jive and I
>> quit. I went on to set up a couple of repeaters of my own, but sold
>> them a while later because I lost interest. One of them is still on
>> the air, high atop Mt Palomar in northen San Diego county.
MvdV> I took the next step. I took a place in the nnational committee
MvdV> that coordinated repeater frequencies in The Netherlands. Until I
MvdV> got tired of settling all the diputes...
I was just going to say that you are a glutton for punishment, but then I
read the final line...:o) Yes, I've dealt with coordinating bodies and
(looking from the outside in), doing so is a PIA. Especially in Souther
Californa, where everybody and his brother has or wants a repeater on the
air.
MvdV> Now I am a member of the comittee that negotiates with the
MvdV> authorities on amateur licence conditions. We have two national ham
MvdV> radio societies here, VERON and VRZA. I represent the latter.
I've backed off of Amateur Radio quite a bit in the last 5 or 6 years. My
HF rig, VHF and UHF radios are all dormant now. The only antenna I have in
the air is a 10mtr vertical and even that radio is sitting there with the
volume down to 0, 99% of the time. I sold a lot of my equipment before
leaving San Diego, 2 UHF repeaters, a truck load of antennas, etc..,
MvdV> You can see a picture at: http://www.vlist.org/nera.jpg
MvdV> I am the guy in the green jacket fourth from the left in the top
MvdV> row.
I picked you out readily enough. LOL! That guy to your left looks like the
typical US HAM, he also looks like a friend of mine in San Diego, AA6EE,
Dewayne Heisse (sp). He looks a bit younger though.
MvdV> The guys kneeling in front are from "Agentschap Telecom" the
MvdV> Dutch equivalent of the FCC. The guy with the red shirt on the
MvdV> right id the fourth delegate from AT. So as you can see the hams
MvdV> got 3/4 of the "Dutch FCC" on their knees! ;-)
:o)
MvdV> The picture was taken last year in the reciever hall of the main
MvdV> Dutch monitor station at Nederhorst de Berg. (NERA). Toy can see
MvdV> some equipment in the background. The occasion was that it was the
MvdV> last time our biannual meetings took place at that location. The
MvdV> station is now disassembled and replaced by a series of unmanned
MvdV> remote controlled station scattered over the country.
That room looks like the control room and some of the labs in the Palomar
Observatory on top of Mt Palomar in San Diego county.
MvdV>>> I have a simple transformer for arc welding. 140 Amps
MvdV>>> maximum. I actually bought it for my son to practise,
MvdV>>> but he soon lost interest so I kept it for myself.
>> What do you use for rod?
MvdV> I mostly use the "universal" 2 mm electrodes. The ones with
MvdV> cladding. The 2 mm is the core, with cladding they come to just
MvdV> under 4 mm.
So it's commercial grade welding rod...I was wondering if you might have
invented a different way to weld.
MvdV>>> I have some pictures of it that I still should put on my
MvdV>>> webiste on the "mistlamp op de kar" sub page. maybe I
MvdV>>> will find the time one of these days...
>> I'd be interested in seeing it.
MvdV> You'v seen them by now.
Yep...
MvdV>>> I never had that myself. But I have worked in an eye hospital
MvdV>>> and so I have seen the results of exposure to UV. Because it
MvdV>>> is not so much the brightness of the light as the UV that
MvdV>>> causes "welder's eyes". Doesn't happen if you are careful
MvdV>>> but if you are sloppy with the hood....
>> It wasn't that I was sloppy, it was because I was the setup
>> person and got the flash off the walls.
MvdV> I see.
>> (I hadn't learned how to weld yet) I spent nearly 6 hours in that
>> weld shop, so I was hurting quite a bit the next day.
MvdV> If you spent that long in it, you should have had some protection
MvdV> even if you did not do the welding yourself. I say the person
MvdV> responsible was negligent for not seeing that you did...
He probably assumed that I knew what I was doing, as I was quite capable
of setting up the fixtures, and had already prepped the stock for weld...
MvdV>>> And the slug around the electrode for arc welding...
>> Yeup. We call it flux rod, but you probably have a different
>> name for it.
MvdV> We usually refer to them as "laselectrode". Th efull name would be
MvdV> "beklede laseelectrode" ("dressed up welding electrode") but that
MvdV> is seldom used as the other type, the naked rod is called
MvdV> "lasstaaf" (welding rod), so there is no confusion.
That's about how it's done here too. One is a welding rod, the other is a
stick (the one with cladding).
MvdV>>> I have no experience with a torch for welding, just for brazing.
>> Well, clothes hangers are made of the worst steel you could
>> possibly find. You don't know what you're getting into until
>> you try that. It's nearly impossible to get a good weld with it.
MvdV> So why didn't he use standard welding rod?
My dad was more stubborn than I am. He probably didn't want to buy the
right welding rod and just blundered along until someone showed him the
error of his ways, my uncle, his brother in law. Who he liked a lot. I got
that coat-hanger story second hand from a welder that I'd taken a job to
and since my name is the same as my dad's, he put two and two together and
told me about how my dad had brought him a job. How my dad had screwed up
by using coat-hangers. I knew better because they teach you these things
in junior high school, but they didn't have those kind of things when my
dad went to school. He learned things the hard way.
MvdV>>> With the electric arc welder, you don't see colours...
>> But you can see the puddle.
MvdV> Yes, and that is where experience comes in. I have too little of
MvdV> that...
Today I found a place that does sand blasting and I took a piece of my 56
Chevy there to have the rust removed. The was an old Chevy frame there
that someone had modified by welding a newer front end on and a newer rear
end, so that he could use modern day running gear. Looking at the welds, I
wouldn't ride in that car for any kind of money. There were bubbles in the
weld, which indicates to me that those welds aren't going to last. Just
because the amateur welder (the owner) couldn't read the molten bubble.
Roy
--- Twit(t) Filter v2.1 (C) 2000
* Origin: Hacienda de Rio de Guadalupe * South * Texas, USA * (1:1/22)
|