Ed wrote:
While I have no disagreement with everything else Ian stated, I do take
some exception to the above comment about foam. Just take a look at RG-8
for example. With all other aspects of it remaining the same, there
certainly is a significant difference in loss figures when the dielectric
is changed from solid to foam.

Significance is in the eye of the beholder. At 400 MHz,
RG-8 foam seems to have a loss advantage over ordinary
RG-8 of ~2 dB per 100 feet. At 10 MHz, it is ~0.2 dB.
Is that significant?
--
73, Cecil http://www.w5dxp.com