i'm in the moment in the phase of refurbishing some of
Drake's 4-line equipment, actually it's an R-4C and SPR-4.
A part of this private project will be to equip these
receivers with modifications, that will be done in a
way, that does the minimum possible change to the original
state of these receivers. The planning incorporates the
following:
- Buffered output of the premixer into a 50[Ohm] jack
in order to connect a external digital frequency coun-
ter (which is already commercially available from a third
party for a very affordable amount of money).
- Buffered output of the final IF (50[kHz]) into a 50[Ohm]
jack. The purpose for this is to run this IF output to
an external mixer, which does a final downconversion to
the 10...18[kHz] freqquency range.
- Design of this external mixer, that does this final
downconversion from 50[kHz] to 10...18[kHz]. The pur-
pose of this mixer is to provide a signal for a power-
ful filter/demodulator software (for AM/SSB/CW), that
is DSP-based (it uses the DSP that is already present
on PC-based soundblasters). This (Windows-based) soft-
ware) is already present for download at the internet
free of charge for HAM's and noncommercial use.
- An extensive (PDF) documentation including images, sche-
matics and measurement results for all the refurbishing/
repair/restauration/alignment work done to these two re-
ceivers.
In order to plan the efforts and grade of professionalism
i will incorporate into this, i kindly ask the list members,
if this may be of any interest for you. In case of suffi-
cient interest, i will do a set of universal usable printed-
circuit boards including extensive documentation, which will
be available for a nominal fee that covers my cost-of-goods.
The planned timeline for the availability of all results in-
cluding bare printed-circuit-boards and documentation will
be appr. 6 months from now on.
So, if anyone is interested in also duplicating this stuff
or in any other participation, please let me know.
Kind regards and vy73
Herbert Schulz
DG7MCC
