Test Equipment Anonymous (TEA) group therapy thread

[BU508A]

Hello,

yesterday I've vistied the HAM fest "UKW Tagung Weinheim 2019"

Here are some impressions, hope, you'll enjoy them.

Hi, at which time did you visit?

I was there on Saturday between 08:00 and 11:30 MEST.

If you have spotted somebody wearing this T-Shirt, then it was me. 

[med6753]

Question for bd139. I haven't really looked yet nor RTFM but I figured I'd cheat and ask anyway.  On the 465B: When removing the Trigger/Sweep board does the sweep switch assembly come out with it or stay in place? 

[bd139]

Sweep switches are all attached to the board. They just pull out with the assembly. It's a bastard job though especially as tek like to just randomly solder a couple of wires here and there just to be dicks. Good luck 

[med6753]

Thanks, I was afraid of that.  The PSU cap replacement is next on the project list and I'm approaching it with a lot of trepidation. Getting those old capacitors out is going to be a real chore. But I have lots of solder wick and liquid flux on hand. This one has the DM44 but at first glance it appears it can stay in place, unlike when working on the vertical board and it has to come off. But no matter, removing the DM44 is real simple and if it has to come off no big deal.

[bd139]

I'm a big fan of dremelling off the legs of the caps first then desoldering what's left. Keeps the thermal mass down and the pads on the board! 

[tggzzz]

I'm a big fan of dremelling off the legs of the caps first then desoldering what's left. Keeps the thermal mass down and the pads on the board! 

How do you stop shards/swarf/powder going where it shouldn't? E.g. into an attenuator range switch

[med6753]

I'm a big fan of dremelling off the legs of the caps first then desoldering what's left. Keeps the thermal mass down and the pads on the board! 

That is a damn good idea. Does away with all that mass pulling the heat away while you try to desolder everything. My dremel is ready. 

[med6753]

I'm a big fan of dremelling off the legs of the caps first then desoldering what's left. Keeps the thermal mass down and the pads on the board! 

How do you stop shards/swarf/powder going where it shouldn't? E.g. into an attenuator range switch

Shouldn't be an issue with reasonable care. The sweep switch will be out and the vertical attenuators are on the other side of the scope separated by the CRT in the middle.

[bd139]

You still have to make sure it doesn't get in anything. It migrates around. See below.

I'm a big fan of dremelling off the legs of the caps first then desoldering what's left. Keeps the thermal mass down and the pads on the board! 

How do you stop shards/swarf/powder going where it shouldn't? E.g. into an attenuator range switch

I usually bag / mask tape the surrounding area. Then it is brushed down twice. That tape seals the entire panel away from the drilling.



Edit: yes that's my drill stand base - a nokia 106 box (and yes the phone is still in it) 

[worsthorse]

This is how it begins. First you get a decent DMM. I dunno, like four maybe five and half digits. Not crazy but pretty damn good. Then you decide to build some kelvin leads for it. Then you figure you'd like to know that it is reasonably accurate, and someone says, for that you should get yourself a DMMCheck and before you know it...

(Attachment Link)

You are spending your evenings figuring out the difference between RN55C and RN55D resistors, sorting 0.1% parts and checking to see if you have any new messages from the volt-nuts reflector. 

Hahaha.

Then you learn there are RN55E’s

I actually just spent £20 on those damn resistors (RN55C). I’m trying to build a band gap reference from scratch with those and a CA3096 transistor array.

I spent maybe an hour looking at sixty dollar    resistors on Mouser one evening.  I knew I had a problem. 

[BU508A]

This is how it begins. First you get a decent DMM. I dunno, like four maybe five and half digits. Not crazy but pretty damn good. Then you decide to build some kelvin leads for it. Then you figure you'd like to know that it is reasonably accurate, and someone says, for that you should get yourself a DMMCheck and before you know it...

(Attachment Link)

You are spending your evenings figuring out the difference between RN55C and RN55D resistors, sorting 0.1% parts and checking to see if you have any new messages from the volt-nuts reflector. 

Hahaha.

Then you learn there are RN55E’s

I actually just spent £20 on those damn resistors (RN55C). I’m trying to build a band gap reference from scratch with those and a CA3096 transistor array.

I spent maybe an hour looking at sixty dollar    resistors on Mouser one evening.  I knew I had a problem. 

Looking at them is not really an issue at all.
But, have you clicked on the order button? THEN you'll have a problem. 

[worsthorse]

I spent maybe an hour looking at sixty dollar    resistors on Mouser one evening.  I knew I had a problem. 

Looking at them ist really an issue at all.
But, have you clicked on the order button? THEN you'll have a problem. 

No but only because I can't bring myself to pay more for resistors than I will for dual-gate MOSFETs.. 

[bd139]

Got a whole bag of 200x genuine RCA 40673’s here. It’s a retirement fund. They haven’t reached stupid prices yet. Last win was a whole bag of OC81D’s I sold to guitar folk  .

Starting to get the voltnut thing. First you buy a voltage reference. Then you buy some divider resistors. Then you set your meter on 10Gohm. Then you realise you need exotic cables. Then you realise you are fighting junction potentials on the leads. Then you need more digits. 

[worsthorse]

Got a whole bag of 200x genuine RCA 40673’s here. It’s a retirement fund. They haven’t reached stupid prices yet. Last win was a whole bag of OC81D’s I sold to guitar folk  .

Starting to get the voltnut thing. First you buy a voltage reference. Then you buy some divider resistors. Then you set your meter on 10Gohm. Then you realise you need exotic cables. Then you realise you are fighting junction potentials on the leads. Then you need more digits. 

200 40673s? Really? I am envious in the worst way.        I've been scrounging for them for almost three years and I've only managed to gather fifty or so, which I've allocated out for projects I want to do over the next couple of years.

[bd139]

200 40673s? Really? I am envious in the worst way.        I've been scrounging for them for almost three years and I've only managed to gather fifty or so, which I've allocated out for projects I want to do over the next couple of years.

Indeed I have. I've got quite a lot of stuff stashed at my parents' house still. I won a crate of parts at a trade auction for £20. Was mostly crap including boxes of Eurohm resistors and two sacks of 7 seg LED displays which went for virtually nothing on ebay but that was in there, my current never ending stash of 2n3904's and 1Kg part used bag of Philips BC108's! The annoying thing is I mostly bought it for the 30 odd tubes of 8051's. Turns out they were bloody OTP ones and had been programmed 

I was actually at the auction trying to bag a Fujitsu Primergy for a startup I was working on which failed miserably  . I didn't win the server 

Edit: I'm going to sell the 40673's when they become worth more than what they are inside. I'm also hawking a ton of ARRL books with designs in them using 40673's as well. I'm the one stop premium ham shop. Here's the outgoing ARRL book pile 



(this is incidentally how I pay for my kit)

[med6753]

Started the deep dive. The DM44 did indeed have to come out to gain access to the daughter board behind the main trigger/sweep board. Taking lots of pictures. 

[tggzzz]

Got a whole bag of 200x genuine RCA 40673’s here. It’s a retirement fund. They haven’t reached stupid prices yet. Last win was a whole bag of OC81D’s I sold to guitar folk  .

Starting to get the voltnut thing. First you buy a voltage reference. Then you buy some divider resistors. Then you set your meter on 10Gohm. Then you realise you need exotic cables. Then you realise you are fighting junction potentials on the leads. Then you need more digits. 

Don't forget the draught excluders/partitions so drafts don't cause differential temperatures in terminals, and ovens, and UPSs so that equipment never has the trauma of being turned off and on.

Oh, and lead compensators such as this:

[bd139]

I feel I may be sucked into this singularity of awesomeness 

[Mr. Scram]

I had all day to do something so obviously I'm rushing to do it with only 30 minutes left to do it.

[neo]

2019 Mena hamfest, kinda boring









I don't even know what the HP 4935A is, or what it does, or if it's even useful! But it was twenty dollars so I figured it was worth at least that in parts.

[bd139]

4935A is a phone line test set AFAIK. Think it allows you to simulate various signal conditions on a line and see how compromised it is.

[med6753]

Bd139, are you sure what you were telling me before applies to the 465B and not the older 465? Here's the front Trigger/sweep board removed. It would appear that while not ideal I now have enough room to get to the capacitors. I really don't see the need to remove the rear board with the sweep control assembly. Am I wrong? And the front board was all plug-in modular and the only unsoldering required was the 2 external trig BNC's.



Here's the Trigger/Sweep board and the DM44 board.

[bd139]

Sorry confused earlier. I thought you were talking about the lever switches. You're good to go with just taking the outside board off.

[med6753]

I was able to pull the board with the lever switches intact. It was tight but it came out. 

[med6753]

2019 Mena hamfest, kinda boring


I don't even know what the HP 4935A is, or what it does, or if it's even useful! But it was twenty dollars so I figured it was worth at least that in parts.

I think that RCA scope is all vacuum tube. If you need help troubleshooting it give me a shout.