On Wed, 2008-03-05 at 22:52 -0600, Bob McGraw - K4TAX wrote:
> Some years ago when working for Sony, we suddenly started having IC socket
> failures in one of our analog multitrack machines. The problem was
> identified as failure of the IC sockets used in the analog audio. When
> questioning the various departments as to why the Augut socket was changed
> to a different model, the purchasing manager said "well, that was the best
> IC socket we could buy for under a nickel. We saved some $10,000 per year
> by making this change". The Augut 800 series was selected as a
> replacement at a cost of $0.23 each in quantities of 100,000. We had
> service engineers travel all over the world to replace some 500 pieces in
> each machine. That's $115 in parts plus about 16 hours labor plus travel
> expense. That totaled about $1500 per machine and some 350 machines to
> re-work. So those nickel sockets cost us about $525,000 not to mention the
> intangible value of unhappy customers.
>
> I'm sure those of us in of have been in manufacturing and or design have
> like stories about the finance department making engineering decisions. In
> the case of the 238 tuner components, in likely 75% or more cases the
> selection of capacitors does not give a problem and thus would seem like a
> reasonable success factor of probability to proceed with the choice. It is
> the 25% that causes the grief.
>
> In my case the 238 tuner on one antenna never shows the heating or SWR
> changing problem regardless of power. On the other antenna on 160M and 75M,
> watch out as SWR will soar with about 800 watts of carrier or more. Below
> that, no problem is observed. One of these days I'll change them out to
> some good quality RF rated caps. Of course in looking at the solution, I
> would be adding about $65 in cost to tuner as well. That passed along to
> the customer could equate to a cost increase of $100 or so. That's a lot
> for a $400 box at retail.
The difference between GP 6 KV ceramics and NPO 1 KV ceramics isn't all
that much. Using a 220 pf, or a couple in parallel at a $1 or $1.25 each
isn't like buying imported RF door knobs at $20 each and is as good.
Trouble is the drifty capacitors won't fail, just they annoy the users
and might lead to PA transistor destruction, which the power supply
current limits or circuit breakers are supposed to prevent.
>
> 73
> Bob, K4TAX
73, Jerry, K0CQ
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|