Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who shares the following:
Dear Thomas my friend,
I built another Tferrite, (TFERRITE 2), for medium waves–this time also with the shortwave option.
A single variable capacitor, 800 pf, and a primary winding on the 2 ferrites of about 46 turns, a secondary winding of 3 turns to pick up the signal and send it to the receiver.
On the PVC tube I wound 4 more coils, for the shortwaves, connecting the ends to the same variable together with the other ends.
I interposed a switch on one end to eliminate or insert shortwaves.
I am sending you these 3 links from my YT channel where you can see the tests I have done in these days with no propagation.
The yield in mediumwave is excellent, like the other one, yet also good for the shortwaves–to be so small it compares very well.
Let me know what you and the whole SWLing community think!
Thanks to you and a greeting from Italy, Formia on the Tyrrhenian Sea.
73. Giuseppe.
Videos
This is brilliant, Giuseppe! Thank you so much for sharing your homebrew antenna projects. It seems they work so well from your beautiful urban location in Italy!
Do you have plans that you can post or send to build these T-Ferrite antennas, thank you.
Mike,
You should follow Giuseppe’s lead.
The lower the frequency the more turns required to become resonant. frequency = 1/( square root of inductance x capacitance). You could increase the capacitance by soldering a ceramic capacitor across the variable one because the type Giuseppe used is the largest variable capacitor made for domestic radios.
As for the ferrite rod, only use one, find one to cover your frequency range in https://www.amidoncorp.com/specs/
Mangosman
Thanks, appreciate it. There are places to get ferrite for those ranges besides Amidon themselves, as well as antennas. Needless to say they can get expensive even though the higher Mu translates to less turns (in theory), though you still need a big cap. The problem remains ferrite is pretty expensive these days, especially trying to make a large antenna out of it! 🙁
I’ve been wanting to ask this for a while: will you build one for LONG wave? I would be VERY interested in the 137 KHz / 2,200m “new” amateur band and (here in USA & Canada) unlicensed LOWFER band 160-190 KHz (kilocycles for old farts 😉
Or for a real challenge, VLF especially SAQ on 17,200 Hz
Is there anything you can actually decode from SAQ or is it just fun to receive something at such a low frequency?