> A typical RF CHOKE is lossy (deliberately) and hence one 
> would not normally 
> use a relatively high-Q PCB track to implement a choke.  

Er, not necessarily.  Having a lossy choke (series DC) is good in that it widens the 
bandwidth, but note that if you have a high power amplifier, drawing oodles of 
current, that series R is going to dissipate LOTS of power.  Not really what you want 
either from an efficiency or thermal management standpoint.  For "de-Qing" the feed 
from a hi-Q inductor, I've often seen a resistor applied in parallel to it.  That way 
most of the DC current goes through the inductor, but as the Z of the inductor 
increases with frequency, the resistor adds a resistive component to the parallel pair 
of components.

> 1/4 wavelength line is not what I would call a choke.  Choke 
> to me is a 
> soggy inductor.  A 1/4 wavelength line is more likely to be a 
> moderate to 
> High-Q resonator and has a different function to the old-stye 
> broadband, 
> flat response chokes.

They're used a "bias feeds" at higher frequencies (microwave especially).  Hi-Z at the 
desired frequency, low-Z at DC.

> Brian G.  and others wrote a spiral track generator for 
> Protel.  Use that.  

OOooo!!  Where's that?!  Does it lock the tracks together so that they don't get 
independently pulled and the group can be drug together?  I've not tried to make a 
"footprint" like this, I've just drawn the thing and had to redo it if I want to move 
it.  Hopefully there's a better way.  I don't live and breathe Protel.

Sorry if the comments are nit picks, but just wanted to provide another POV.

Thanks & regards,
-- 
Mark Randol, RF Evaluation Engineer
Motorola SPS, Inc.
M/S EL536
2100 E. Elliot Road
Tempe, AZ 85284
(480)413-8052 Voice
(480)413-8690 FAX
<mailto:[EMAIL PROTECTED]> 

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