[TenTec] paragon II performance on longwave band??

[Kevin Purcell]

On Sep 26, 2007, at 6:45 PM, Bob McGraw - K4TAX wrote:

> Nope, Tentec radios overall have excellent receiver performance.

in partial response to John Ferro

> i love this radio, but i have found one negative with the paragon  
> and that is LW reception. i sometimes like to listen to the NDB's  
> (navigational beacons) below the broadcast band, but the paragon II  
> is pretty deaf down here. is this consistant with ten tec radios?  
> do they supress reception down in this area?

One additional point is the RX320 and RX320D both are much less  
sensitive below 1.8MHz.

The issue on this radio is the input coupling transformer doesn't  
work as well at LF.

There are several third party mods for this radio for LF performance  
(basically replace the T3 tranformer with something with higher  
inductance) and it seems that TT made a similar change in at least  
some of the RX320D radios to improve MF and LF response by replacing  
T3 with a small toroid with 9 turns rather than the solenoid core  
tranformer.

For example,

<http://www.amrad.org/projects/lf/rx/RX320LFMod.pdf>
<http://www.tentecwiki.org/doku.php?id=rx-320>
<http://www.tentecwiki.org/doku.php?id=rx-320d>
<http://groups.yahoo.com/group/RX320/message/10144?threaded=1&var=1&l=1>

Check the Paragon II circuit diagram. See what they have at the front  
end of the RX (BCB LPF? not so good tranformers?).

One could see this as a conscious design decision too. The roll off  
helps when it keeps unwanted MW AM and LF stations out of your HF  
front end.
--
Kevin Purcell
kevinpurcell at pobox.com


--
73 DE N7WIM / G8UDP
Kevin Purcell
kevinpurcell at pobox.com