Customs Charge Threshold

[Radio Fixer]

No! aint got the time to check but if you buy from Farnell they will be traceable and to proper specs.

How much are you going to save / radio on buying unknown stuff?

Gary

[Andy M0FYA]

What is the source for the resistors? Are they approved back to a recognized standard? I'm always dubious about buying stuff from Ebay be it HK or anywhere else. Whats the point of building in possible future faults to save small bucks?

Gary

Gary, before I order a couple more resistor values, I'm just wondering if you have any specific concerns based on a bad experience of packs from HK.
Certainly the resistors are anonymous, without any paperwork. But if we assume the resistance value measures correctly (in tolerance) which would be grounds for asking for a refund, how might they be defficient? Bearing in mind that although rated at 3W, they will typically be used where a 0.5 or 1w carbon composition resistor was originally specified.
I suppose they might be less stable or noisier than a 'quality' metal film resistor, but probably still better than the old carbon types?
What are the failure modes of metal film resistors?

Many thanks,

Andy

[AlanBeckett]

If they really are Metal Film - Spiral cut - then the failure mode is O/C.

Alan

[Andy M0FYA]

If they really are Metal Film - Spiral cut - then the failure mode is O/C.

Alan

They are actually described as 'Metal Oxide Film' - is this the same as 'Metal Film', or is the resistive element literally a metal oxide or a metal respectively, ie quite different technology?
Which metal?
No mention of 'spiral cut', and looking at some others which I think came from the same source (I didn't order them, bought by a friend and then split between us) I can't see evidence of a spiral.

Andy

Andy

[Andy M0FYA]

OK, having sent the previous post I went to Wikipedia (which I should have done first....).

This tells me

"Metal-oxide film resistors are made of metal oxides such as tin oxide. This results in a higher operating temperature and greater stability/reliability than Metal film. They are used in applications with high endurance demands"

Andy

[Radio Fixer]

I have no experience of failing HK components as I have never bought from there and wouldn't.

To me the extra cost of buying from a reputable source IE: Farnell, RS etc is worth it for peace of mind. I'm not doing huge numbers of radios... and per / radio its probably a next to nothing. If you are changing every one and are very short of cash it may be for you.

Here's a Farnell data sheet and there are traceable standards referenced.


  423658.pdf (Size: 115.85 KB / Downloads: 33)

PS: I spend a huge number of hours on most radios I restore and wouldn't want to take a chance on cheap items from dubious sources.

Gary

[AlanBeckett]

Metal Oxides fail in the same way.

Alan

[Yorkie]

I know we're drifting right of topic and the original query has been answered, but what the heck, we're allowed to ramble and here without an avenging angel swooping down from on high to kill the thread.

Wherever we buy our bits from, (eg, e-bay or re-sellers such as RS, Farnell, whoever), there's an almost complete certainty that components are made in China.

Why?

Because that's where most of the equipment that the components go into are made, so it makes sense for the bits to be made there. Take well known names such as Vitrohm and Ferroxcube as examples. Both are own by the Yageo Corp'n (Yageo.com). Yageo was establsiehd in 1977 and is the worlds No1 for chip resistors, No 2 for MICCs (Huh?), and No 3 for ferrite components. It has a turnover of 890mill USD. Where are the markets for its components? 68% in China, 23% in Europe, 7% in Asia, and 2% North America. On which stock exhange is Yageo quoted? Taiwan. Nuff said! The West hardly makes and stuff any more - heck, we hardly mend it, let alone make it. (When I say 'we' I generalise - I don't mean we the forum members, 'cos mending stuff is what we do!).

Whilst it's true of course that UK distributors do supply data sheets and I don't doubt the integrity of their corporate governance or the products they re-sell as distributors, (just as customers didn't doubt Tesco's integirty to not sell horse meat labelled as beef), it doesn't automatically follow that anything that doesn't come from UK distributors is of dubious quality. Chances are (though admitedly we're in the dark about it), the stuff bought from e-bay HK sellers may well come out of the same factories - metal film resistors aren't the sort of things that can be made in small backyard huts after all. Leastways, I dont think so. No - they're made to be used in their millions by consumer electronics firms in China. We are way down the food chain from that. Or so it seems to me.

Just musing really - it's not an issue for me - I buy so few resistors and caps and they're so cheap anyway, that I can get the few that I need from UK sources.

But let's face it, the passage of time has shown that Brit brands such as Hunts were not a byword for quaity and reliability.

All the stuff I've bought from China has been very high quality, at ludicrously low prices and often unobtanable from other sources. Digital meter modules, frequency counter modules, small amplifiers - all sorts of bits and bobs at 'Buy Now' prices. All from firms such as Asia Engneer who have done tens of thousands of trades with excellent feedback. What feedback is there from RS, Farnell, Maplin, Rapid et al? None - so we don't know, other than from our own expeirneces and hearsay, how they are performing..

The main downside of buying from China is the long delivery times that ensue, but stuff usually arrives in 3 weeks or so. I'm rarely in much hurry any way.

Rambled and dribbled Yorkie.

[Radio Fixer]

I don't know about electronic components but for windsurfing equipment, even when items are made in the same factory, they have different specs depending on the company who designed them. They will come down different production lines and have > or < quality control. For electronic components they could be made differently, certainly to better or worse designs and be 100% tested or just come off the end into a bandolier and ship.

You pays your money etc

Gary

[AlanBeckett]

I suspect that Resistors are made in somewaht larger quantities than windsurfing equipment, and in a much more automated manner.

Alan