[R-390] Slighty OT: Question about tantalum caps

[Barry]

I think I mentioned on this list that I'm in the process of thinking about 
considering the possibility of maybe one day building a 9VDC power supply 
for one of my radios.  Yes, it's solid state and begins with a "G" (and ends 
with "rundig") so if you want to stop reading here, I understand.

I was getting the parts list together and the circuit calls for a few 
miscellaneous caps, one being a 47uF 50V Solid Tantalum cap.  Perusing the 
Mouser catalog, I find this capacitor is quite expensive (in excess of $20 
each).

Can anyone explain to me the advantage of using a solid tantalum over some 
other "plain-jane" capacitor?  The circuit uses an LM317K and this 
particular capacitor is connected across the output just before the ammeter 
and voltmeter.  (The circuit is in the 1978 ARRL Handbook (page 127)).

I was fortunate to have meters that will make the project nice and figured 
that would be lion's share of the cost, but this little cap (along with a 
couple of other items) have really driven the cost of building this thing 
nearly out of sight.

Can someone/anyone tell me if another type of cap would work as well?  Are 
the caps of today better than those of 30 years ago, so much so that maybe 
the solid tantalum wouldn't be necessary?

Thanks!

Barry - N4BUQ