Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
tggzzz:
--- Quote from: bd139 on June 10, 2018, 02:07:53 pm ---
--- Quote from: med6753 on June 10, 2018, 02:03:56 pm ---
--- Quote from: bd139 on June 10, 2018, 01:57:59 pm ---Couple of quick test gear related pictures as I'm still dead in the water here.
Worst illustration and explanation of point award goes to RSGB from the full license revision book :palm: ... doing the exam this week so having a quick scan...
I can see sooooo many things wrong there.
--- End quote ---
Shouldn't that work better if it were a feed thru termination?
--- End quote ---
Yes generally a good idea to use a through termination. The SWR is going to be shit on a T-piece though. Fine for audio. I can see the following things that are wrong with it however:
1. The T-piece is usually connected to the scope in the middle so it's the wrong T piece.
2. The T-piece indicated can't be plugged into the scope because the gender is wrong.
3. Through termination as mentioned is definitely better.
4. Don't connect the probe to the T piece, it's not a 50 ohm match to the DUT.
--- End quote ---
... and it will still have 15pF/20pF in parallel - and you can use a Smith chart to see the significant effect that will have on response at even 100MHz.
But what the hell is the RSGB doing suggesting using a scope for anything RF related? Looking at baseband signale != RF, of course :)
tggzzz:
--- Quote from: med6753 on June 10, 2018, 01:59:07 pm ---Are there sections of London that are really that bad? NYC used to have "no go" sections but that's no longer true...although some neighborhoods are "safer" than others. Now the same can't be said for cities like Chicago or Detroit.
--- End quote ---
No London isn't that bad!
BTW, it isn't just NYC; my parents experienced that in several forms in Pittsburgh in the "golden era" late 50s. Naturally I won't be responding to any replies, on the basis this any such conversation will rapidly devolve.
tggzzz:
--- Quote from: Specmaster on June 10, 2018, 03:05:28 pm ---
--- Quote from: bd139 on June 10, 2018, 01:03:57 pm ---Either that or it was Leyton and he's now in Whipp's Cross hosptal with a stab wound :-DD
--- End quote ---
Quick update, I'm not in any hospital nor on the way to one, meter is stashed in the car, when I get back with it I'll fire it up and post pictures of it, cost was just £35 at the end so well worth a punt cos I can get that back at least as spares if need be 🤣🤣
--- End quote ---
I'd have taken a kettle lead with me. But then I take a TDR to geek car boot sales to measure RF cable/connectors impedance :)
(I'll be selling one such TDR soon, when I've got suitable batteries. The ones I've just received only have <70% of the stated capacity)
bd139:
--- Quote from: tggzzz on June 10, 2018, 04:00:29 pm ---
--- Quote from: bd139 on June 10, 2018, 02:07:53 pm ---
--- Quote from: med6753 on June 10, 2018, 02:03:56 pm ---
--- Quote from: bd139 on June 10, 2018, 01:57:59 pm ---Couple of quick test gear related pictures as I'm still dead in the water here.
Worst illustration and explanation of point award goes to RSGB from the full license revision book :palm: ... doing the exam this week so having a quick scan...
I can see sooooo many things wrong there.
--- End quote ---
Shouldn't that work better if it were a feed thru termination?
--- End quote ---
Yes generally a good idea to use a through termination. The SWR is going to be shit on a T-piece though. Fine for audio. I can see the following things that are wrong with it however:
1. The T-piece is usually connected to the scope in the middle so it's the wrong T piece.
2. The T-piece indicated can't be plugged into the scope because the gender is wrong.
3. Through termination as mentioned is definitely better.
4. Don't connect the probe to the T piece, it's not a 50 ohm match to the DUT.
--- End quote ---
... and it will still have 15pF/20pF in parallel - and you can use a Smith chart to see the significant effect that will have on response at even 100MHz.
But what the hell is the RSGB doing suggesting using a scope for anything RF related? Looking at baseband signale != RF, of course :)
--- End quote ---
Pretty much fine for HF power meaurement through up to about 20m band however. “Within 10%” is mantra there. VHF forget it. They did actually mention that 20-30Mhz scopes were affordable but forget anything above that. :palm:
RSGB training material is total shit. Just some hoops you need to jump through. They’re making it harder. I got 100% on both foundation and intermediate tests and did sod all revision to give you an idea how easy it is. I’m no exam wizard for sure. The full license is just another hoop. 62 multiple choice questions a monkey could answer and a 60% pass rate doesn’t stop a lot of people getting on the air who really shouldn’t be.
When I say on the air I mean licensed to operate 400W TX that they built themselves. Scary thought looking at some of the things I heard uttered on this subject.
Specmaster:
I'm back and just about to eat, so I'll post photos later, but powered up, display as I thought a bit on the dim side but thats not too bad as displays I think are available, tested it against my voltage standard and its spot on and agrees with the 3478A and the 3466A's and resistance looks to bank on the money as well, for £35 it looks like a real bargain after all, winner winner, chicken dinner, see yall later :-DD
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