[1000mp] Compare FT990

[Mike Gilmer, N2MG]

Having never seen a 990, I cannot say how Yaesu approached the problem, 
but having witnessed a few plug-in designs...

1. If there are a LOT of coaxial interconnects, these are fairly 
expensive in the form you are advocating.
2. The PC boards would need to be designed so that all the leads came 
out the connecter edge (including the problematic 50ohm runs) - this 
takes some doing (multi-layer might be needed) and can have performance 
problems.
3. The "motherboard" can get to be quite complex - multi-layer again.  
Adding a new interconnect requires the MB be modified as well as the 
destination boards.
4. Overall packaging is constrained by the plug-in concept - with 
the "MP" for example, they can and do put boards anywhere and 
everywhere and they can be all different sizes.  With the plug-in 
design, juggling functions around because one runs out of room on 
cookie-cutter-sized boards can be a pain.

IMO, plug-in boards lend themselves more to very high volume, or very 
expensive designs. Even though the 1000MP/D/MPV/MPVF are several grand, 
they are NOT expensive by my definition (well, yes, they are to me and 
my hobby, but I'm talking about $10K, $20K and up devices).

My guess is that they may have had too many problems (cost or 
development time or...) on the 990 that they abandoned the concept.  
Maybe the chief advocate for that kind of design is no longer there to 
champion the cause.  Too bad.  Troubleshooting to the board level can 
sure be easy if one can swap boards with a friend!  Surely you can't 
think Yaesu cares much about that.

73 Mike N2MG

The following message was sent by "Garry Shapiro" <garry@ni6t.com> on Thu, 11 Jul 2002 19:36:21 -0000.

> One might ask how that is so considering all the added cables/headers, the
> assembly time for the interconnects, and the extra testing.
> 
> Garry
> 
> Joe Hanna:
> >
> > Cost!
> >
> > Garry Shapiro wrote:
> >
> > > What I recall of the FT990 (from Conway Reef, 1995) was that it
> > had a fine
> > > RX, and that it was constructed like a quality computer, i.e. it had a
> > > backplane and plug-in cards. That meant a minimum of
> > interconnecting cables,
> > > headers and coax leads, and easy access/replacement, which
> > suggested higher
> > > reliability. I recall being surprised and nonplussed that Yaesu's
> > > contemporary and subsequent efforts abandoned that approach and
> > returned to
> > > multiple boards in every nook and cranny, interconnected with
> > (far too many)
> > > cables. Anyone who has removed the main board in an MP to
> > replace or add a
> > > component will appreciate this.
> > >
> > > Perhaps someone out there in MP-land can tell me why the
> > card-and-backplane
> > > approach was abandoned.
> > >
> > > Garry, NI6T