[TowerTalk] Ferrites 31 vs. 77 material

[jimlux]

On 11/5/19 4:21 AM, Rob Atkinson wrote:
>> My gripe is that simply bashing anything made in China is decades out of date and a bad generalization.
> 
> Gripe all you want but you've used a few examples to try to refute a
> generalization that has basis in fact.   There are far too many cases
> of poor products from outside US and Europe, not just China, that
> disagree with your belief.

And in the US, to be honest.

I suspect that China comes in for a lot of bashing (some is justly 
deserved) because of the opaqueness - a billion people running what 
seems to be 10 million small shops that come and go, like mayflies - 
along with a language barrier, etc.

If you are a US based customer, it's easier to find out about flaky US 
suppliers - the people complaining are doing so in English, if nothing 
else.  Certainly there are suppliers and vendors in the US that if 
someone were to come to me and say "we're going to get X from Y" I might 
say "you know, you might find that Z is a better source".  Someone in 
China looking to contract something out in the US wouldn't have that 
ability.

I'm sure that if you were Chinese and in China, you'd have a similar 
experience. You'd *know* who the reputable and reliable players are, and 
who to stay away from.  You'd know the things to look for in their 
marketing materials that indicate they're "fly by night, running an 
illegal second shift in a friend's facility" - Most of us here in the US 
would have no clue.

The other thing is that the incredible volume and rapidity of trade with 
China on a small scale (we're not talking about container ships full of 
steel - I'm talking a few cubic meters at a time, or less) has been 
enabled by the Internet - Just as "no one knows that you're actually a 
dog on the Internet" - you can have a very professional appearance, and 
be able to deal with small orders in a relatively frictionless way, but 
be totally incompetent and unreliable.  In pre-internet days, vendors 
like this couldn't survive - in either US or China.

You'd get your business by personal contacts, by your sales rep going 
out and pounding the street, by going to trade shows and talking to 
customers, etc.   That's where the big mail-order vendors got started 
(the Allied, the Newark, the Farnell, the Digikey) - was for small 
buyers to get things without having to go through the dreaded 
"distribution" (like Avnet) or "samples" where the first question was 
"how many thousand parts a month will you be buying".   Sure, you paid 
more for DigiKey, but they are the ones who ventured out from the wilds 
of Minnesota to the vendors and trade shows, and decided what to put in 
the catalog and what not to carry.  This is an essential intermediation 
function.

The internet enabled disintermediation (i.e. cutting out the middle 
man), but also put the responsibility of detecting lame suppliers on the 
end user.  You paid less, but you have a higher "scrap rate"





> 
> Chinese vacuum tube production is all over the place--some are great;
> others flash over.  Consumer products missing RFI suppression
> components, and then there's steel quality which has been known to be
> life threatening when used in critical structural applications.  US
> Gov't procurement has a whole course on how to spot knockoff hardware.
> Would you go up a tower made in China with Chinese ceramic insulators?
>   (This is Towertalk after all.)  On the other hand, smartphones from
> off shore seem to have no issues.    Obviously, when manufacturers
> enforce QC and micromanage the process, things go well.
I don't know that mfrs "micromanage" the suppliers - it's more a matter 
of "making the deal with the right supplier" - something that is 
incredibly difficult to do with email from 10,000 miles away.   The mfrs 
who are successful have people who are local as well as significant 
travel from the US, and "keep in touch".
> Otherwise.....cheap ham handy talkies for $20 are the result.

And those units actually work pretty well - and are probably responsible 
for more people getting involved in ham radio.

Now, if they'd just start making $50 HF radios..


> 
> I never knew anything about the QC variations in ferrite until K9YC
> mentioned it.

It's actually not a QC issue - it's an inherent part of the 
manufacturing process - the *design tolerance* for materials used for 
EMI suppression is quite loose. It might be a manufacturing yield thing 
- you could get 1% or 5% tolerance cores, but they'd be really 
expensive, because they would essentially screen them post manufacturing.

The Ferroxcube (I think) doc described that it was the mechanical 
finishing/grinding process that set one of the limits - it's a sintered 
granular material - you can only machine to a certain tolerance.

No matter how skilled you are, and how many inspectors watch you do it, 
your sand castle at the beach is never going to be mirror finish.  If 
you grind limestone or shell based sand really fine, and run it through 
a kiln, that sand castle will have much better mechanical tolerances, 
but it's not the same material as the quartz sand at the beach.

(I'm in California - beach sand is coarse, and hard, like the sea gods 
meant it to be - that fluffy, cake flour-like sand in Florida or the 
Caribbean is unnatural <grin>)