fanatical mega-loopstick question


sloshatron <wa1gwh@...>
 

Hi Gary;

When you measure the recycled coils on the LCR meter, are you
checking only the L or are you somehow taking into account any C
differences between the original and tranplant coils (either on or
off the ferrite bars)? This would be the distributed capacity of the
coils.

If this is working with just L measurements that would be great and
much easier for folks to duplicate.

Also, I'm still thinking about air core coils (small loop antenna
style) to replace the original ferrite loopstick. I realized that if
spider web construction was used it would be much easier to take off
turns and portions of turns and if necessary to add them back on if
the best spot was missed in the iterative alignment process. A
spider web coil form could be cut out of plastic with one spoke
extending way out to mount the form to the radio in the same way as
your ruler idea.

TNX,

Garry Nichols
near Syracuse, NY


Gary DeBock
 

Garry and Guy,
 
     All of the mega-loopsticks (7", 14" and 21") have been constructed using an LCR meter to measure inductance only, to ensure that the recycled coils (mostly salvaged from the vintage long ferrite bars) match the  SRF-39 stock coils in inductance.  The alignment procedure, in which the small coil is slid along the ferrite bar to peak a low-band (usually 600 kHz) signal,  optimizes the match between the recycled coils and the SRF-39 circuitry, making it unnecessary to measure capacitance and resistance during the construction process.  As long as the inductances match, and the 600 kHz peak is sharp, the newly recylced coils are perfect for DX reception in the SRF-59.
     As for comparison of the ferrite mega-loopsticks and  spider coils, I'm sorry that I have never experimented with spider coils, or air-core loops.  The ferrite mega-loopsticks seem to be great for DX, relatively cheap, and still quite portable.  The only drawback is that you inevitably make longer and longer ones, as you fanatically strive for the highest sensitivity level.  Eventually you need to face the reality that doorways are only 30" wide.
     Guy, if you wish to make some spider coils and compare them to the mega-loopsticks, you can borrow them at any time (Guy and I live in the same city).  As of today, all of them will still fit through a doorway  :>)
 
                                                                                           73,  Gary
    
   




Planning your summer road trip? Check out AOL Travel Guides.


Guy Atkins
 

Hi Garry,

I had been thinking about spider coils also for an ultralight. How large of a coil form do you think would be needed to compete with a hot rodded ferrite loop? Also, do you envision concentric coils on the form separated by a distance or one continuous coil with tap points as needed?

Guy Atkins
Puyallup, WA USA
www.perseus-sdr.blogspot.com

Sent via BlackBerry from T-Mobile

-----Original Message-----
From: "sloshatron" <wa1gwh@twcny.rr.com>

Date: Sat, 05 Apr 2008 22:58:16
To:ultralightdx@yahoogroups.com
Subject: [ultralightdx] fanatical mega-loopstick question


Hi Gary;

When you measure the recycled coils on the LCR meter, are you
checking only the L or are you somehow taking into account any C
differences between the original and tranplant coils (either on or
off the ferrite bars)? This would be the distributed capacity of the
coils.

If this is working with just L measurements that would be great and
much easier for folks to duplicate.

Also, I'm still thinking about air core coils (small loop antenna
style) to replace the original ferrite loopstick. I realized that if
spider web construction was used it would be much easier to take off
turns and portions of turns and if necessary to add them back on if
the best spot was missed in the iterative alignment process. A
spider web coil form could be cut out of plastic with one spoke
extending way out to mount the form to the radio in the same way as
your ruler idea.

TNX,

Garry Nichols
near Syracuse, NY