Re: How To Calculate Ferrite Loopstick Inductance Values for Ultralites?


Michael <michael.setaazul@...>
 

Jerry, I assume you are referring to your longwire setup.
If so, the external coupling ferrite and parallel tuning capacitor
will not be very critical. As long as it peaks the wanted frequency,
optimisation in terms of rod and litz specification, number of turns, position
on the rod will not make a lot of discernable difference. Moving the
coupling rod relative to the receiver will, as you have already ascertained,
allow you to find a rough optimum. Changing the L/C turns/capacity
might improve selectivity, but probably not noticeably. More important
is avoidance of too close coupling, which might "derail" tracking of
the internal varactor C in the radio.

Optimising the quality of the external L winding would become more
relevant if it were to be directly connected into the radio so as to tune
with the internal DSP varactor, in lieu of the internal ferrite winding.

The next step up in terms of selectivity would be to add a Q-multiplier
or regenerative RF-amplifier to the coupling ferrite L/C. (We would
need expert opinion to know whether that might disqualify the setup
from uldx criteria, however.)

I dont have the real estate for a real longwire or beverage, but your
observations are beginning to tempt me to experiment further again :-)

Happy hunting!

Michael UK

----- Original Message -----
From: jerry_popiel
To: ultralightdx@...
Sent: 28 July 2011 22:54
Subject: [ultralightdx] How To Calculate Ferrite Loopstick Inductance Values for Ultralites?


This question is likely for the Experts. How do you know what Inductance values are acceptable for
MW and LW Listening? That is, I have an older 5.5 inch Ferrite Bar Antenna with approx 80 turns of
Litz wire on it, that I am using to couple to a PL 380. It measures 0.671 mH on my DM 4070 LCR
Meter. Is that Inductance Value acceptable, or what is / or how do I know what is the required
value?

Or does this depend on the length and diameter of the Ferrite Bar - such as the 122 turns and 1700
uH of 100/44 Litz wire that Gary DeBock has said is required for his 7.5 Ferrite Rod Antenna for the
Pl 380? Any replies would be very much appreciated

Jerry



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