[TenTec] Argosy RF attenuator mod

[Kevin Purcell]

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 at 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 at pobox.com