[TenTec] paragon II performance on longwave band??

[Bob McGraw - K4TAX]

The Paragon does have an overload issue derived from nearby BC stations 
{50KW at 30 miles or less} when used with long antennas for the 100 KHz to 
1.7 MHz band.  Long antennas as in 1/2 wave for 0.5 MHz or so. (900 to 1500 
ft}  The Paragon II does not have this problem as the front end design was 
changed as stated to prevent overload from BC stations.  Yes, there is some 
sacrifice with performance below 1.7 MHz.  There is also some different 
switching configuration for the attenuator on the input between the Paragon 
and Paragon II.

73
Bob, K4TAX




----- Original Message ----- 
From: "Kevin Purcell" <kevinpurcell at pobox.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Cc: "Kevin Purcell" <kevinpurcell at pobox.com>
Sent: Wednesday, September 26, 2007 10:34 PM
Subject: Re: [TenTec] paragon II performance on longwave band??


>
> 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
>
>
>
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