[Hallicrafters] HA-20 Coupler

[Rocco Lardiere]

Dave,

Yes, the HA-20 has a coupler.  It is shown in the schematic, Fig 30, in
the SR 400A manual.  

The coupler is similar to many others from this period.  If you can't
find an original (good luck), you might look for the Knight Kit SWR
meter from the early 60's - the design is very similar - two pickoff
lines on either side of a transmission line center conductor, with
diodes and appropriate wiring.  There is nothing critical about the
level of pickoff - it's all relative.  You do want one that will show a
50 ohm impedance, of course.  

I think Heath used something similar in the original 50's SWR meters -
but the Knight Kit pickoff is a separate box with similar wiring, like
the Hallicrafters.  No doubt there are others out there.

73,

Rocco Lardiere N6KN

David McCombs wrote:
> 
> Hello all,
> 
> The manual on my HA-20 mentions a 'coupler' of which coax runs through, and
> three additional wires are used to connect the pwr/swr meter.  There is no
> picture of this 'coupler' in the manual.  Can someone tell me what it is, or
> better yet, if this is an additional piece that I don't have does someone
> have an extra to sell?
> 
> Thanks,
> Dave
> 
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