[R-390] HP-8601A?

[2002tii]

Barry wrote:

>Anyone have experience with an HP-8601A, particularly for aligning 
>R390s, etc?  It seems like a decent generator as it covers
>the entire spectrum needed for these radios and I *think* it is 
>fairly leakproof.  Just wondering if there are any
>particularly bad things about them that would make them not a good 
>choice for this application.

It's a useful piece of equipment, but IMO clearly in the "don't pay 
real money for it" class.  I've seen a few go for $200 or more at 
auction, which I think is way too high -- you can get an OK 8640B for 
that money if you look.  If you find an 8601A that works for $50-75, 
however, that's another story.  My experience is based on buying 
three working units with relatively minor problems for $40, and 
fixing them up for friends (during which process I learned more than 
I really wanted to know about them).  They are not easy to work on.

Stability is decent.  I never measured leakage, but I never noticed 
any problem in this regard.  The 8601A has a fair degree of line hum 
(mostly 120 Hz) that appears as FM on the RF output.  I found it was 
virtually impossible to remove.  If having a sweep generator is one 
of the reasons for considering the 8601A, its sweep mode is pretty 
clunky.  The calibrated sweep widths (in symmetical sweep mode) only 
go down to 100 kHz above 11 MHz, and only to 10 kHz below 11 MHz, so 
you're left to use the vernier and guess how much sweep you're using 
for most radio alignment tasks.

Like many RF generators, the attenuator is not well protected against 
overload, so you need to be sure nobody ever transmitted into it 
(which, for some reason, is much more common than I'd expect).  My 
advice for anybody who may ever hook up a transceiver to a signal 
generator is to leave a 20 dB coaxial pad permanently installed on 
the generator output.

Best regards,

Don