Test Equipment Anonymous (TEA) group therapy thread

[factory]

Anyone want 2x HP 400E’s that require some work?

https://www.ebay.co.uk/itm/184674196350

Bit too modern for me, I tried & failed to win a 1960's 400E on ePay last week, it made £52 which seemed a lot considering it was grubby looking and had no feet.
https://www.ebay.co.uk/itm/133659380818

David

yes that's a bit much for such an item. I'm not sure what has gotten into people to be honest. I'm going to stick with my 8060A for AF stuff and the Fluke RF probe for the higher frequency things I think.

I did think long and hard at what the failure mode is likely to be and I know the switching assembly on them and then the idea wore off  . If it was £20 the pair I'd just do it for the parts potentially but the seller I know won't take offers that are much lower than the offering price.

The other problem with them is the 50% chance the meter zero adjustor will fall off after being kicked about and dropped by the courier/postie.

David

[bd139]

Indeed

Think I'm on to a winner on ebay. Bought a rare item from someone who doesn't know the value (£20 -> sells for £250). He asked me about the accompanying thing and if I want that as well - let the negotiations begin and have asked him how much. The last one that went on ebay went for £886! Hoping he says £50 or something 

Should pay the TE bill 

[med6753]

Indeed

Think I'm on to a winner on ebay. Bought a rare item from someone who doesn't know the value (£20 -> sells for £250). He asked me about the accompanying thing and if I want that as well - let the negotiations begin and have asked him how much. The last one that went on ebay went for £886! Hoping he says £50 or something 

Should pay the TE bill 

You know, I've done the same thing here and thrown out teasers which makes everyone wonder and want to know what was scored. But I'm such a hypocrite because I want to know RIGHT NOW what you got...or are getting. 

[bd139]

If I end up with it (or don't) I'll post back 

[Specmaster]

I remember seeing that fire on TV which just reinforced my fear that I would never, ever, live in a high rise tower. But unfortunately some people have no choice for a variety of reasons.

Some people choose to, e.g. that build that is tilting in downtown San Franscico, or this 1400ft elegant mess in New York:
"Some of the billionaires at No 432 are now fighting with the developers — and each other — over myriad issues including millions of dollars in water damage from plumbing and mechanical faults, frequent lift malfunctions and walls that disconcertingly ‘creak like the galley of a ship’. The worst of the banging, groaning and clicking noises is produced by the communal rubbish chute that ‘sounds like a bomb’ when bags are dropped down it."
https://www.dailymail.co.uk/news/article-9225763/Residents-blighted-leaks-floods-tallest-residential-building-world.html
https://www.skyscrapercenter.com/building/432-park-avenue/13227

You softie 

Actually in some houses that might have fitted OK, my neighbours on each side, that have fitted in a real treat as their hallway goes from the front straight through to the back 

[med6753]

Well, hurry up. 

I didn't think I would notice any difference in going from 60mbps to 200mbps but surprisingly I have noticed some sites, such a Gmail, loading considerably faster.

But I haven't noticed any difference on video content such as the Firestick. 

[bd139]

You've only got one user. I've got two teenagers on my line. That's where it really makes a difference 

[Specmaster]

You've only got one user. I've got two teenagers on my line. That's where it really makes a difference 

Yep, on the money again, there is always 4 users in my house, and we have multiple things permanently connected as well.

[bd139]

Ok it's a Mizuho MX-7s 40m CW/SSB transceiver. Rare as hell Japanese thing. They go between £330-£870ish here for a working one. But it's fucked. Says it's off frequency and sent me some photos of everything except the battery compartment. So I asked for that and yep it's leaked. Can see corrosion on the main board in some of the photos. Someone will buy it but I don't want to deal with it. Shame!!! Fucking Duracells I bet.

Either way I got the matching PA yesterday for £20 which will be tested, repaired if necessary and listed again.

If anyone sees one of these globally for a silly price without nuked batteries, buy it then sell it again auction immediately.

[mnementh]

The fridge I modified to use as an air source heat pump must be well over 30 years old.

My SIL's father is an HVAC engineer and we have chatted about a/c and what are common faults, and the subject of compressors did come up.
Seems the lubricating oil for the pump is not separated from the refrigerant (if I understood what he was telling me), and so you are told to let a fridge etc stand for an hour or two after transporting it so that the oil can properly drain back into the pump, in case it's managed to get into the pipework.

I expect running it without the full complement of oil is likely to shorten the service life to some degree.

It's weird the conversation turned back around to refrigerators; as I was going to post that I've seen exactly that same "melted & metal solder balls" failure mode in numerous run caps on compressors. I don't imagine SIL's father would consider consumer-grade refrigerators to be in any way "proper" refrigeration... that was the general attitude towards them from my shop foreman at the ding & dent appliance store and the crusty old commercial refrigeration techs I worked with at Kalamazoo as a teenager. The latter often said if it didn't use ammonia, it wasn't refrigeration. 

The thermodisc (a prehistoric cousin to the PTC polyfuse) does not work as well as many people assume; compressors fighting to run with a weak run cap will often get quite hot before it trips, and repeated cycles do seem to increase the threshold to such a point where they'll get blistery hot.

It was SOP at the ding & dent appliance store to test every run cap with a cap analyzer (Google Annie Cap Analyzer for some right proper horror shows - these are a scary bit of kit even if used properly) for value & leakage as part of the prep procedure; I found an amazing number of toasted thermodiscs and leaky/toasted run caps on units that appeared to run perfectly well, aside from current draw just a bit on the high side of MFR specs. If the current draw didn't drop down considerably with replacement of the thermodisc and cap, we knew that unit was not long for this earth.

As for the letting it stand upright; that is because the compressor inside a sealed unit runs submerged in an oil bath inside that welded canister. In normal operation, that oil only circulates along with the refrigerant in a vapor state. When the unit is transported on its side, the oil will travel into passages meant to carry only vapor. If the compressor is started with liquid oil in those passages, the oil is drawn directly into the compressor and it hydrolocks. The tolerances on modern compressors are so tight that this can damage rings and valves. On a used unit, any wear-induced particles are supposed to ultimately dump into that oil bath and be trapped there. As with any such system, the fine particles will turn into a sludge due to settlement. If this sludge is part of the oil which makes it to a vapor passage, it can clog the orifice/expansion valve.

In an ideal world, there would be a dessicant/particle filter in the high side to trap all this; and on many there are simply because it greatly decreases the infant mortality rate and is good for the brand. But on many there are not. Another victim of the race to the bottom, I imagine. 

We knew to look for this on the units we serviced; they were much more likely to respond well to a simple thermodisc/run cap replacement and be a good reliable unit after burn-in.

mnem
 

[mnementh]

Talking of which need to replace my fridge. Compressor is not making happy noises. Had it 12 years approx so not complaining.

It may just need a refrigerant recharge. Problem is finding someone to do it properly. You don't just "top it off" and call it good as many hacks will attempt. Proper method is pump down and recovery of all old refrigerant and leak check. Then recharge with new refrigerant and compressor oil.

You're thinking automotive refrigeration. Most consumer-grade refrigerators are a sealed system that is literally welded shut everywhere; they cannot lose refrigerant unless there is a leak. Unless that leak is obviously caused by an accident like impact damage to a copper tube, the entire system is suspect as a corrosion victim and only a really expensive box is worth the cost of correctly doing a evap replacement (the most common leakage point) and recharge.

Consumer refrigerators have a lot of objectively hinky manufacturing in them; the prevalence of compression-coupled copper-to-aluminum joints is a real weak point service-wise. While it is much cheaper to crimp/swage the aluminum evap or the condenser tubes in a fridge directly to the copper compressor tubing from a manufacturing standpoint, it makes reliable repair very difficult. Replacement parts which have a copper stub to silver-solder (high temp; almost brazing) to are usually more expensive than you can sell all but the most expensive fridges for used once you factor in the cost of flushing and recharging the unit.

There are some expensive units that are based on commercial refrigeration; these are designed to be repaired and have fittings for your gauges built-in. But in general, if it doesn't have those fittings, it's really not meant to be repaired and you're fighting an uphill battle against corrosion leaks, clogged evaps, orifices and damaged compressors that are just hanging on by a thread. If there's a problem other than simple electrical, recycling the damned thing is better for your peace of mind and for the world as a whole.

mnem
 

[bd139]

Now this is why I don't care and am just going to replace it. I have no idea what any of that was all about and I do know when I know too little about something to not kill myself fixing it

[Cerebus]

Well, hurry up. 

I didn't think I would notice any difference in going from 60mbps to 200mbps but surprisingly I have noticed some sites, such a Gmail, loading considerably faster.

But I haven't noticed any difference on video content such as the Firestick.

Not surprising, most things optimised for download run from 1Mb/s (megabit per second) to 8Mb/s at the extreme. Most 1080p streams are in the 2-4 Mb/s region. I keep most of my stored video at 2.5 Mb/s for H.265 and 4.5 Mb/s for H.264 for 1080p25 and any faster produces no noticable quality improvement.

[med6753]

Talking of which need to replace my fridge. Compressor is not making happy noises. Had it 12 years approx so not complaining.

It may just need a refrigerant recharge. Problem is finding someone to do it properly. You don't just "top it off" and call it good as many hacks will attempt. Proper method is pump down and recovery of all old refrigerant and leak check. Then recharge with new refrigerant and compressor oil.

You're thinking automotive refrigeration. Most consumer-grade refrigerators are a sealed system that is literally welded shut everywhere; they cannot lose refrigerant unless there is a leak. Unless that leak is obviously caused by an accident like impact damage to a copper tube, the entire system is suspect as a corrosion victim and only a really expensive box is worth the cost of correctly doing a evap replacement (the most common leakage point) and recharge.

Consumer refrigerators have a lot of objectively hinky manufacturing in them; the prevalence of compression-coupled copper-to-aluminum joints is a real weak point service-wise. While it is much cheaper to crimp/swage the aluminum evap or the condenser tubes in a fridge directly to the copper compressor tubing from a manufacturing standpoint, it makes reliable repair very difficult. Replacement parts which have a copper stub to silver-solder (high temp; almost brazing) to are usually more expensive than you can sell all but the most expensive fridges for used once you factor in the cost of flushing and recharging the unit.

There are some expensive units that are based on commercial refrigeration; these are designed to be repaired and have fittings for your gauges built-in. But in general, if it doesn't have those fittings, it's really not meant to be repaired and you're fighting an uphill battle against corrosion leaks, clogged evaps, orifices and damaged compressors that are just hanging on by a thread. If there's a problem other than simple electrical, recycling the damned thing is better for your peace of mind and for the world as a whole.

mnem
 

I kinda suspected they weren't easily serviced but wasn't sure.

[med6753]

Ok it's a Mizuho MX-7s 40m CW/SSB transceiver. Rare as hell Japanese thing. They go between £330-£870ish here for a working one. But it's fucked. Says it's off frequency and sent me some photos of everything except the battery compartment. So I asked for that and yep it's leaked. Can see corrosion on the main board in some of the photos. Someone will buy it but I don't want to deal with it. Shame!!! Fucking Duracells I bet.

Either way I got the matching PA yesterday for £20 which will be tested, repaired if necessary and listed again.

If anyone sees one of these globally for a silly price without nuked batteries, buy it then sell it again auction immediately.

Someone is sneaking back into the Ham community. Next week we'll hear stories of trying to hang an antenna without pissing off the neighbors. 

I have some bib overalls and flannel shirts on order for you so you will fit right in with those hobos. And stop bathing and grow a scraggy beard. 

[mnementh]

<SNIP>Well that is certainly not what I expected as everyone seems to think 75 Ohm is inferior. Just a  thought, you're certain that the traces have not been incorrectly titled

In a coaxial system, all else being equal including shield ID, a 75R system has lower loss but 50R has higher power handling. Hence use of 50R for transmitting systems and 75R for Video, Cable TV receive antenna systems.

For long antenna runs the saving in line loss may be more than the mis-match loss. An example of this is the Trimble Thunderbolt GPSDO. The receiver and antenna are 50R but Trimble recommend using low loss 75R Cable TV coax.

Speaking of scraggy beards, this crusty old bastard presents the "Why 50 ohms...?" question it in a pretty digestible form. The TL/DR is it is a compromise between optimal power-handling and minimal attenuation for small signals.

But his shirt is too clean. 

mnem
 

[bd139]

Ok it's a Mizuho MX-7s 40m CW/SSB transceiver. Rare as hell Japanese thing. They go between £330-£870ish here for a working one. But it's fucked. Says it's off frequency and sent me some photos of everything except the battery compartment. So I asked for that and yep it's leaked. Can see corrosion on the main board in some of the photos. Someone will buy it but I don't want to deal with it. Shame!!! Fucking Duracells I bet.

Either way I got the matching PA yesterday for £20 which will be tested, repaired if necessary and listed again.

If anyone sees one of these globally for a silly price without nuked batteries, buy it then sell it again auction immediately.

Someone is sneaking back into the Ham community. Next week we'll hear stories of trying to hang an antenna without pissing off the neighbors. 

I have some bib overalls and flannel shirts on order for you so you will fit right in with those hobos. And stop bathing and grow a scraggy beard. 

I know easy money when I see it, that's all. Bored hams sitting there are prime ebay mugging territory at the moment 

Actually I need a shave 

Realistically I have some RF projects on the go in my head. NONE of them involve talking to hams though 

[mnementh]

You've only got one user. I've got two teenagers on my line. That's where it really makes a difference 

Yep, on the money again, there is always 4 users in my house, and we have multiple things permanently connected as well.

In most cases, the upgrade in downlink speed is accompanied by increased uplink speed. Once you get above  30-50Mbps, this makes a lot more difference in usability and responsiveless than the additional downlink speed. Where lots of downlink speed really helps is when you have multiple users streaming video, provided you have a modern WiFi router with multi-path/multi-link capability. Then you don't have constant buffering incidents because of 3 people (oh, and your neighbor leeching off you) watching cat videos on iPuds & smartPwns while you're trying to watch a movie.

mnem
 

[Cerebus]

Now this is why I don't care and am just going to replace it. I have no idea what any of that was all about and I do know when I know too little about something to not kill myself fixing it

Wise, even if you knew what you were doing you'd take a look inside a typical domestic fridge/freezer, look at the places where you'd have to access pipework and ultimately take a brazing torch to while fixing things, and you'd go "Nope!".

[mnementh]

Been dere, dunnat, burned the shirt. While I was wearing it. 

mnem
*fssssssssssssssss....*

[Cerebus]

I have some bib overalls and flannel shirts on order for you so you will fit right in with those hobos. And stop bathing and grow a scraggy beard. 

Wrong clothes for the UK. A chunky home-knit cardigan, an English "country check*" flannel shirt, baggy high-waisted trousers in some dark green or brown polyester designed to simulate wool, and sandals worn with socks in the summer and brown brogues in winter.

* Only the label will be "C&A" instead of James Meade (who make quite decent sgirts).

[dl6lr]

Ain't it funny how they did stuff back then !
No wonder they were hard to recognise.

These are plain tin can transistors in TO-7, the packaging were very much the same at that time for a lot of small signal transistors. The only thing in this radio is, they put them into rubber grommets and perhaps they fastened them with a wire slung around it. As transistors were expensive at that time, they made some povisions against damage by vibration, I bet.

[med6753]

Well I was going to do some TEA today but got busy with weekly domestic responsibilities such as sweeping, dusting, vacuuming (hoovering).

A woman's work is never done. Now going to get something eat and turn on TV with those glorious 200 channels of not a damn thing to watch. Although the lady is pleased that she can now watch some her regular shows next weekend when she comes up. Which is I suppose good for me since I won't have to be subject to anymore "East Enders" crap.   

[Saskia]

*sigh*  workin on movin stuff outta da way.

FFS how did we end up with that much crap.

[mnementh]

Amen².

mnem