[TenTec] Argonaut 505 alignment, filter, mod?

[Neil Martinsen-Burrell]

I am the proud new owner of a fine condition Argonaut 505.  I'm very happy
to find a five band QRP rig that is happy running off a 12V battery, even
if it is 40 years old.  I do have a few questions and this seems like the
best place to ask.

1) The receiver seems a bit deaf on 80m ( by A/B comparing with a TS-520)
and I wonder if the problem could be solved by following the alignment
procedure in the manual.  I can get my hands on an oscilloscope, but I
can't tell by looking inside what hand tools I need to do the actual
adjustments.  What are the proper tools to perform an alignment for this
radio? And where is a good place to get them?


2) I am primarily interested in CW with this radio and so I am looking for
a narrower audio filter.  I have seen a Model 208 CW audio filter for sale,
but it is set up for use with the accessory jack on the Argonaut 509.  The
TenTec wiki says "a slight modification is necessary when using the filter
with the older Model 505 Argonaut. Service Note SN-6-505 details the
modifications."  I assume that the slight modification is to separate out
the audio in, audio out and power in lines.  Does anyone know how to obtain
a copy of that service note for more details?


3) Some have suggested that an audio filter outside of the AGC loop is not
very useful.  Comparing the schematic of the Argonaut 509 to that of the
505, it appears that the patch point for the audio filter on the 509 which
is inside the AGC loop could be added to the 505 as well.  Does anyone know
if this mod is possible or desirable?  I have seen people talk about these
radios as collector's items and this one appears unmodified, so I would
also welcome thoughts on when it is appropriate to make a modification like
this.

Thanks in advance for any help you can offer on any of my questions.

-Neil KD0UKC