Adding an attenuator to the Argosy is perhaps one of the best things
you can do.
The RF amp is always in circuit in the Argosy in front of the mixer
which for the low bands is just not needed. The noise figure of the
antenna is much higher than the noise figure of the front end. But
due to some cunning design the RF amp is reused as a post-mixer
driver in the transmit chain so it's difficult just to take out of
circuit.
The nice feature of the 1980s TT rigs is they're separate boards
linked together at 50ohms so it's easy to grab a signal and
manipulate it rather than hacking on a PCB track.
There is a nice rx only link from the LPF board to the Mixer board
that you can use install a attenuator.
WA3IFY, how did you add yours?
A remotely switched PIN diode attenuator? A idea for this mode was
described by G0FAH Sprat and mentioned in Radcom (Technical Topics,
July 1987). It was reprinted in Technical Topics Scrapbook 1985-89 p
181. It's rather similar to the technique used in the 546 series Omni
73 Kevin
On Sep 26, 2007, at 11:25 AM, wa3fiy@radioadv.com wrote:
I've made a few mods over the years to
improve the AGC, added a 20db front end attenuator, etc.
--
Kevin Purcell
kevinpurcell@pobox.com
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