Re: Ferrite antenna advice for LW


Gary DeBock
 

Thanks Marc and Steve,

Longwave-optimized loopstick design was a fascinating challenge, since no commercial manufacturer had ever included such a loopstick in any of their portables. It was really a "start from scratch" design effort.

The full details of the 2010 experimentation leading to the 7.5 inch (19cm) Longwave-optimized loopstick for the DSP Ultralights is posted at 
https://dreamcrafts.box.com/s/rmcd8wpt81pw1oobcl6om1pwhsqny0gd

73, Gary
    


-----Original Message-----
From: Marc Coevoet <sintsixtus@...>
To: main@ultralightdx.groups.io
Sent: Sat, Jun 18, 2022 12:08 pm
Subject: Re: [UltralightDX] Ferrite antenna advice for LW

I remember Gary making very good antennas for am and lw for tecsun/silabs radios like the 310 or 380.  But they had a different number of turns (more for lw) to match the needed coil inductivity for am/lw.  So thats also why old radios like grundig have different coils ...  Unfortunately tecsun did not adapt for lw ...

Marc Coevoet

Op za 18 jun. 2022 20:13 schreef <jgriff670@...>:
I have a Tecsun PL-330 which is known to be very deaf on LW. I also have a Roberts R993 (quite basic transistor radio) which has very good LW sensitivity. As a little project, I took the internal ferrite antenna for the Roberts and used it to make an external antenna for the Tecsun, following a procedure analogous to the one here https://swling.com/blog/tag/xhdata-d-808-modifications/ - I simply soldered the ends of the LW coil to a 3.5mm plug which is then inserted into the external antenna jack on the Tecsun

However, this only gives the Tecsun about the same sensitivity as when using its own non-optimal internal ferrite antenna. Can anyone advise me on how I could improve the LW sensitivity further? Would it help to include a variable capacitor to tune the receiver coil? Should I be able to expect the Tecsun to get the same sensitivity as a transistor radio with the same ferrite antenna or is there another reason why transistor radios perform better for LW?

I am a complete beginner so any advice would be appreciated!

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