Test Equipment Anonymous (TEA) group therapy thread

[WastelandTek]

easy now

[beanflying]

I blame the vinegar fumes for my possibly off comment above

File renovation today. I have my own but this collection is my Dad's and Grandfathers that spent most of the existence next to the ocean. Chemical resharpening and final rust removal after removing the pins, scunge and miscellaneous detritus. Ready for the next few decades.

The collection is mainly Australian made Wiltshire but contains Canadian Nicholson, and a few from Sheffield

[tggzzz]

File renovation today. I have my own but this collection is my Dad's and Grandfathers that spent most of the existence next to the ocean. Chemical resharpening and final rust removal after removing the pins, scunge and miscellaneous detritus. Ready for the next few decades.

How does chemical resharpening work? In my ignorance I assume chemicals would preferentially attack the thin pointy sharp bits.

[beanflying]

The theory is is takes metal from the top and front faces equally. Given I only left them in for about 10 hours on a hot day the sharpening effect is likely minimal. They are more sharp for the gunk and iron oxide removal than for metal removal I suspect.

That said quick test of even the very fine pitch ones feel much sharper to the touch and working really well.

Time well spent compared to buying quality replacements at $20-50 and the cheaper ones above a needle file just don't cut it  (pun intended)

[Saskia]

forgive my ignorance, but why not put them into an ultrasonic, add the rust removal and cleaning solution and turn up the heat ?

[VK5RC]

Just vinegar or something else?

[beanflying]

Because I don't own an ultrasonic bath for a start

Acid dipping because what I was shown a very very long time ago and a quick check of what people are now doing shows it is still valid and in use. Straight vinegar too @vk5rc then an alkali wash and clean rinse.

[VK5RC]

👍

[Saskia]

Because I don't own an ultrasonic bath for a start

Acid dipping because what I was shown a very very long time ago and a quick check of what people are now doing shows it is still valid and in use. Straight vinegar too @vk5rc then an alkali wash and clean rinse.

ok, that explains it  When repairing corrosion or repairing stuff I usually throw it into an ultrasonic after finding the fault to
- clean it
- remove corrosion
- remove flux
- remove baked in blurp

Depending on your cleaning solution and the ultrasonic settings the results are very promising.
Even entire pinball wiring harnesses including coils and switches come out very nicely. It just saves such an incredible amount of time.

[bd139]

Power meter done. This came from the realisation that I wasn't going to pay MFJ £34 for a piece of inaccurate shit when I can make myself a piece of inaccurate shit for about £15 with a decent sized meter I can actually see.

Turns out this is actually usable to well past 150MHz (!) which was a surprise.

Outside. Caffeine shake wibbly lines FTW.



Guts. Not pretty but that's how you get low VSWR.



Now to build some power attenuators to push it up to 200W!

[Martin.M]

make a rebuild of my RD1 ,
it is a trustful shunt for something what is hard working at the antenna output 

or the Heartkit Cantenna , a food can filled with a gallone of transformers oil .. the book for the homebrew I have here.
Don`t forget please to use the thick cables, my SK1 oldie have fried some meters from the RG58 by testing the output from the tube.

[bd139]

I nearly bought a Cantenna a few months ago. Would have been a good investment. Decided that blowing 50W out per attenuator was probably less messy than dealing with oil even if it does keep me warm in winter.

Anyway next project is actually finishing off the thing that this is going to be plugged in to. This is the pseudo bitx which is going into the HP enclosure I have lying around (yes that project I started over a year ago is still going). As always, being a software guy, I wasn't happy with the original firmware so I rewrote it all using AVR-libc from scratch. I've also built the PA which will blow out 50-80W or so quite happily. But all the other bits are missing because they weren't as interesting. At least the IF strip is done and aligned!



Temporary enclosure for ref 

[med6753]

Power meter done. This came from the realisation that I wasn't going to pay MFJ £34 for a piece of inaccurate shit when I can make myself a piece of inaccurate shit for about £15 with a decent sized meter I can actually see.

Turns out this is actually usable to well past 150MHz (!) which was a surprise.

Outside. Caffeine shake wibbly lines FTW.



Guts. Not pretty but that's how you get low VSWR.



Now to build some power attenuators to push it up to 200W!

I think it looks damn good.  That's what "homebrew" is all about. Carry on......

[mnementh]

Not nearly enough hand-wound toroids for the target user base. Needs to be much more complicated.

mnem
Uh-oh... forgot the top off the basket in my coffee pot this morning. EXTRA TEXTURE!!! 

[bd139]

I'm winding those glorious bastards now 

[mnementh]

Somehow, I KNEW you would be.

mnem
*inducted*

[mnementh]

...Apart from that, I explained it badly. The concept is to encourage the parents to believe that they shouldn't inflict their little darlings on you.

But then you miss out on the joy of teaching them horrible, disgusting campfire songs and filling them with caffeine & sugar until they vibrate just before handing them back to their adoring parents. 

mnem
I would NEVER do that. Unless it was absolutely, positively hilarious.

[mnementh]

Power meter done. ...Guts. Not pretty but that's how you get low VSWR.      Now to build some power attenuators to push it up to 200W!

Kinda surprised you didn't leverage that huge chunk of AL box as your heat-sink. 

A little thermal goose-grease on the joint between front/back and you would probably not have too bad of a hot-spot, plus should keep stray capacitance from that big heat-sink floating in the air inside of the ground plane to a minimum. The goose-grease is probably not strictly necessary, but it can't hurt; plus a wet joint right close to where the angry pixies are dancing would reduce the chance of crusties causing resistance/capacitance between front/back.

But mostly thinking of the stray capacitance of that heat-sink.

mnem
  *fulminating at the mind over my morning cuppa chunky homestyle coffee*

[mnementh]

Because I don't own an ultrasonic bath for a start

Acid dipping because what I was shown a very very long time ago and a quick check of what people are now doing shows it is still valid and in use. Straight vinegar too @vk5rc then an alkali wash and clean rinse.

If you don't have any industrial alkali products, you can scrub with Windex afterwards. Any decent quality window cleaner refill will do well; as long as it has enough ammonia (alkaline) that you can smell it. Then a rinse and/or scrub with distilled water and blot with a towel. Then put in the oven at low heat to dry completely; as hot as you feel comfortable handling them with gloves on (for me, this is about 300°F), This causes the metal to expand, opening up all the micro-fractures on the surface so it readily absorbs your oil treatment.

 I used to use ordinary motor oil or 3-in-1 Oil; with the advent of readily available full-synthetic in low viscosities like 0W-30/0W-20 I started using that to wipe my files down between applications of the file card. I've found it does seem to promote smoother cutting, especially in "drag-filing"; and it repels clogging noticeably better, especially with soft problem metals like aluminum.

mnem

[tggzzz]

...Apart from that, I explained it badly. The concept is to encourage the parents to believe that they shouldn't inflict their little darlings on you.

But then you miss out on the joy of teaching them horrible, disgusting campfire songs and filling them with caffeine & sugar until they vibrate just before handing them back to their adoring parents. 

mnem
I would NEVER do that. Unless it was absolutely, positively hilarious.

Don't need externally applied chemicals; internally generated ones are sufficient Such generation can be stimulated by

• going from 0-55mph in 5s with their bum 9" off the concrete
• pulling 3G and feeling their cheeks being dragged towards their shoulders
• pulling 0G, and watching mud floating in front of their face
• falling out of the sky, with only 10s to live  - unless they dive harder at the ground and then pull 3G
• eyeballing sheep as they whizz past at 65mph, or raptors at ~0mph

... which provokes either adrenaline or a spaced out smile. If it provokes neither, then their parents are more than welcome to keep the.

And I would always do that, even though hilarity probably won't ensue

[bd139]

Kinda surprised you didn't leverage that huge chunk of AL box as your heat-sink. 

A little thermal goose-grease on the joint between front/back and you would probably not have too bad of a hot-spot, plus should keep stray capacitance from that big heat-sink floating in the air inside of the ground plane to a minimum. The goose-grease is probably not strictly necessary, but it can't hurt; plus a wet joint right close to where the angry pixies are dancing would reduce the chance of crusties causing resistance/capacitance between front/back.

But mostly thinking of the stray capacitance of that heat-sink.

It was some careful experimentation that lead to that hunk of crap. I actually started with a bit of RG174 on the end of the BNC connector but the mounting turned out to be a complete bastard and the VSWR was poor so I tried soldering it to the BNC connector itself. That worked nicely to 150MHz so I dared not touch it. Heatsink goes around it. I could probably mount it flat to the front panel but it's a bit of a pain as I wanted a 50mW-ish input as well.

Anyway got fed up of toroids so dug out another project from a long time ago that still works:



That was only supposed to knock out a couple of watts but I've been futzing with it and an MRF237 to give it more grunt. Now to try and make some contacts on minimalist kit. No computers involved!

[Saskia]

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[bd139]

I’d have loved that job

[Saskia]

that's where I first ran into R+S (EK-56, my all time favorite).

[Martin.M]

R+S, yes