Max,

You'll have a hard time finding an original Hy-Gain Penetrator in good
condition after all these years.

However, the design of a 5/8 wave with full-size ground plane has been
taken up to the next performance level by my good friend 'Jay in the
Mojave Desert', just up the road from the filling station:

http://www.a1antennas.com/

Check out history page.
--
Philip de Cadenet G4ZOW
Transmitters 'R' Us
http://www.transmittersrus.com