5" FSL Antenna Construction Project Update


Guy Atkins
 

Hi Ryan,

This is great to know. Thanks for letting us know that the 1162/46 Litz can indeed by bought by the foot from the Mkmak222 seller.

73,

Guy Atkins
Puyallup, WA


---In ultralightdx@..., <rmartin100@...> wrote :


I found out ebay seller Mkmak222 does sell the 1162/46 litz by the foot. You have to order the whole spool and include a note in the order specifying length needed. He then refunds the difference back to your paypal account.
Ryan


Ryan Martin
 


I found out ebay seller Mkmak222 does sell the 1162/46 litz by the foot. You have to order the whole spool and include a note in the order specifying length needed. He then refunds the difference back to your paypal account.
Ryan


Rik
 

Gary-

You have a good memoty, thanks.

Do you credit the sharp tuning more to the ferrite or the Litz. What would happen if an air core loop was made of the same Litz wire? How big would you guess it would have to be to compete reasonably well with this FSL?

Thanks- FARMERIK


Gary DeBock
 

Hi FARMERIK,
 
Great to hear from you again!
 
<<<  Can a FSL antenna be used at home where there is some RFI?   >>>
 
Sure-- most FSL antennas are actually used indoors, and they provide good reception as long as you don't place them next to a computer, plasma TV or other heavy-duty RF polluter. Almost every home has some RFI issues, but you can minimize the problem by placing the FSL antenna away from the RF polluters, and close to an external window facing the desired direction of DX signals.
 
<<<   Is the pick up pattern on an FSL terribly narrow so it must point exactly toward a station?    >>>
 
No, the pick up pattern of an FSL antenna (like all figure-8 antenna patterns) is fairly broad, so unless you are close to a null direction (with the ends of the ferrite rods pointing directly at a station) you should get good reception. On ocean coast cliff sites I can direct the FSL's optimal reception at 270 degrees, and receive signals from both Australia (240 degrees) and Japan (300 degrees) at the same time.
 
What IS critical about an FSL antenna is the razor-sharp tuning adjustment. You need to be right on frequency for the best inductive coupling results, and this is why the 8:1 drive variable capacitors are so important. This high-Q tuning arrangement helps to reduce the splatter from off-frequency pest stations when you use it correctly, but it can also reduce the signal quality of the DX station if you don't carefully adjust the variable cap to an exact frequency match.
 
73, Gary DeBock (in Puyallup, WA, USA) 
 
 
      
 
 

-----Original Message-----
From: farmerik@... [ultralightdx]
To: ultralightdx <ultralightdx@...>
Sent: Sat, Nov 22, 2014 6:17 am
Subject: [ultralightdx] Re: 5" FSL Antenna Construction Project Update

 
Gary-

 I have two quick questions-
 Can a FSL antenna be used at home where there is some RFI?
Is the pick up pattern on an FSL terribly narrow so it must point exactly toward a station?

Thanks- FARMERIK


bbwrwy
 

Not as successfully.  They are sensitive to RFI.  However, because of the cold weather I use mine 
indoors.  Just unplug as many appliances as possible, especially anything using AC/DC power 
adapters like the ones used with an iPad or iPhone. 

Good DX.

Richard Allen.


Rik
 

Gary-

 I have two quick questions-
 Can a FSL antenna be used at home where there is some RFI?
Is the pick up pattern on an FSL terribly narrow so it must point exactly toward a station?

Thanks- FARMERIK


Ryan Martin
 

I made the mistake of buying the 1200/46 litz from Canada last winter. I was unimpressed with the performance of my 5" FSL with that wire. It was slightly better than my select-a-tenna but worse than my 18" air core loop! So it sat on a shelf unused ever since. I should have listened to Gary when he said don't substitute litz. Live and learn I guess. If anyone wants to buy the remaining 62' of 1162/46 litz(the good stuff) for $50 shipped and insured(US only), please let me know.
Ryan


Gary DeBock
 

Hello All,
 
For Ryan Martin or any others who plan to construct one of these 5" FSL antennas this winter, there is some updated information that may be helpful.
 
The original 5" FSL antenna construction article ( http://www.mediafire.com/view/9ze98h293s85p86/5%20inch%20FSL.doc ) was written in February of 2012, and has been downloaded almost two thousand times from the MediaFire site. A demonstration video of this 5" FSL antenna is posted at http://www.youtube.com/watch?v=A1gfUeoQhHQ
 
1)  Because of the purchasing demand for the 140mm x 8mm Russian surplus ferrite rods called for in the article (and also called for in the 7" FSL construction article) the Ukrainian eBay sellers have raised their prices many times for these rods, taking advantage of the many hobbyists who have ordered material for these projects. This has driven the cost of purchasing these ferrite rods far above the original (February 2012) price, which in turn has driven the construction cost of the entire project above the original $95 target 
 
There is nothing magical about the 140mm x 8mm size of ferrite rods called for in the article! A very reliable eBay seller is offering 125mm x 8mm ferrite rods at less than half the price per rod ( http://www.ebay.com/itm/Small-balun-ferrite-rods-8x125-mm-Lot-of-50-/400706626766?pt=LH_DefaultDomain_0&hash=item5d4bf9e4ce ) and the FSL performance difference between the two sizes of ferrite rods would be negligible. Save yourself some serious $$ by purchasing the 125mm x 8mm ferrite rods, and simply add a couple of extra Litz wire turns to compensate for the slight difference in ferrite rod inductance.
 
2)  Since the February 2012 article was written some new, higher diameter Litz wire (which provides more FSL sensitivity) has been introduced on eBay by Mkmak222, a very reliable seller. My recommendation is to go with the new 1162/46 Litz wire instead of the 660/46 Litz wire called for in the article. This higher diameter Litz wire (available at http://www.ebay.com/itm/Type-2-Litz-wire-1162-46-AWG-100-feet-/151156887668?pt=LH_DefaultDomain_0&hash=item2331a71074 ) will provide a significant sensitivity boost for your 5" FSL antenna. Bear in mind, however, that since this new Litz wire is of a higher diameter than the 660/46 wire the resulting FSL coil will be significantly wider for the same number of coil turns, spreading out to cover the ferrite rods to a much greater degree. The same number of coil turns should be used as called for in the article, however (26 for the 140mm x 8mm ferrite rods, but 28 if you use the much less expensive 125mm x 8mm ferrite rods).
 
3)  The supplier of the "N50P" variable capacitor (Crystal Radio Supply) is no longer in business. An acceptable substitute for the variable capacitor (of almost the same size and construction) is the "365-8-1" offered by the Midnight Science crystal radio parts suppliers at http://www.midnightscience.com/catalog5.html#part3 
 
Good luck to all who are considering the 5" FSL project!
 
73 and Good DX,
Gary DeBock (in Puyallup, WA, USA)