Re: 3" FSL Tecsun PL-380 Construction Parts-- Availability Update


Gary DeBock
 

Hi Bill,
 
<<<   Thanks for posting the link to your article. In all that I've read about the FSL, I haven't seen any "directivity" comparisons given between the various implementations. Your thoughts.   >>>
 
As for "directivity," the FSL antennas have a figure-8 (non-cardiod) reception pattern, and are not very directional in the desired angle of reception. As long as the antenna bearing is with about 30 degrees of the desired DX station's bearing, there isn't very much difference in signal strength. When the angle is greater than 60 degrees the signal drops off noticeably, however. When DXing on the Oregon cliffs you generally can choose between Asian stations (around 300 degrees) and DU stations (from 210-240 degrees), but not both.
 
FSL's can be made extremely directional for nulling pest stations, however. The new 3" FSL Tecsun PL-380 models can null out almost all of my pest stations, but the null bearing must be within about 1 degree of the station's bearing in order to do this. When you get a couple of degrees off of the null bearing the pest station strength is as strong as ever. An extremely clean RF reception pattern is important for these nulls; the FSL coil must be as symmetrical as possible, and lead-in wires must be as short as possible. The hard-wired FSL's have a critical advantage in this aspect, since there is no variable capacitor to disturb the clean RF reception pattern.
 
73, Gary DeBock (in Puyallup, WA, USA)
 
 
 
 
 
 

-----Original Message-----
From: Bill bill@... [ultralightdx]
To: ultralightdx
Sent: Mon, Jan 18, 2016 2:06 pm
Subject: Re: [ultralightdx] Re: 3" FSL Tecsun PL-380 Construction Parts-- Availability Update

 
Gary,

Thanks for posting the link to your article. In all that I've read about the FSL, I haven't seen any "directivity" comparisons given between the various implementations. Your thoughts.

Regards...Bill

On 1/18/2016 1:46 PM, D1028Gary@... [ultralightdx] wrote:
 
Hi Farmerik,
 
<<<   Tell me more about this 'Sensitivity Rating' please.    >>>
 
The FSL "sensitivity rating" formula was determined after detailed A/B experimentation with 8 different FSL test models in 2012. The full details are contained in the article posted at  http://www.mediafire.com/view/6oyoldllrbiwf91/FSL_Antenna_Design_Optimization.doc 
 
The "coil diameter times ferrite length" sensitivity rating system only applies for true FSL antennas using the same type of Litz wire, same ferrite permeability and the same construction components. As such, there is no way to judge the sensitivity rating of your antenna compared to FSL antennas, Farmerik.
 
73, Gary deBock (in Puyallup, WA, USA)
    
 
 
-----Original Message-----
From: farmerik@... [ultralightdx]
To: ultralightdx
Sent: Mon, Jan 18, 2016 9:07 am
Subject: [ultralightdx] Re: 3" FSL Tecsun PL-380 Construction Parts-- Availability Update

 
Tell me more about this 'Sensitivity Rating' please. For example, my toroid stack uses  3 inch coils over a 13.5 inch long stack. What would that rate? It has very sharp peaks when pointed exactly at a station, but does not null out completely other stations a few degrees off to the sides. I hear a much improved S/N exactly at one direction on the target station though. And compared to my short 500 foot BOG most all other weak  stations on a frequency disappear, since the short BOG is not terribly directional at most AM BCB frequencies I think. - FARMERIK

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