[Test-Equipment] HP 1740A delay line fix?

[Mike Manes]

Hi,

My HP 1740A has recently lost over 20 dB vertical response at 100 MHz
relative to 10 MHz (and no, the BW LIMIT switch was off :=}.  I traced
this to a nearly identical relative loss between the input and output
of the delay line, measured using a hi-Z RF probe.  DC ohmmeter checks 
show that the line is neither open nor "lossy" or shorted at DC.

I've been told that this line can sometimes be "fixed" via manipulation
of some sort, but if that fails, are there any sources for replacements,
either HP or other?  The manual says the line's differential Zo is 
180 ohms (90 + 90?) and 100 nsec electrical length (but nowhere close to
15m physical length).  

I'm willing to live without the delayed trace, but sure need the 100 MHz
response.  Any caveats re simply replacing the line with a short pair
of 93-ohm coaxes?

73 de Mike W5VSI
-- 
Mike Manes    manes at attglobal.net     Tel: 303-979-4899
"Things should be made as simple as possible, but not more so."  A.
Einstein