Peter P. wrote:

>>>> buy nH inductor kit
>>> 
>>> Yeah. Get the kit where you also get a complimentary bridge in the
>>> desert included. 
>> 
>> I didn't understand this... I guess you mean it's not worth it? 
> 
> Yup. It would be a box with pieces of wire and instructions to avoid
> bending them or putting them near any metal or dielectric ... 

I thought about SMD inductors, and about repeatability. Keeping a tight PCB
layout with short traces to reduce dependency on the PCB and using
inductors that come with reasonable tolerances would make it more probable
that the next device works like the one before -- I thought. Did I think
wrong?

> [...] they cannot predict the real situation. As I said, small details
> can pull the frequency off 1-3%. That's 10 MHz at 433 MHz (way too
> much). 

I have to continue discussing this... When I look at a typical keyfob, they
seem to use standard SMD capacitors and inductors -- with tolerances
probably more than 3% (at least 5%). And yet they seem to work fine,
probably without individual adjustment. From this, I gather that the
frequency of the LC resonance being off 3% can't be that crucial... Again,
am I wrong?

> Try very hard to locate a place where they have a specan. Any lab that
> does cell phones or handy phones (UHF) should have one. Or try to rent
> from an equipment supplier.

Good idea; I'll see what I can find.

Thanks,
Gerhard

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