Re: Graham Maynard's Tecsun PL-380 Modification Article
sdwillingham
Stephen,
Please don't go cutting up the plastic in your PL-380. An antenna that gives a (claimed) 10 dB more gain will make your overload problems worse. Antenna gain simply is not a panacea. Perhaps it would help to know what happens to that gain. When large signals are present, the Si4734 simply "turns down" the gain of its amplifier chain to compensate for the excess gain. Only when all signals are weak will more wideband antenna gain be helpful. Even then, loopsticks contribute substantial noise of their own to the signal. Once the loop's noise exceeds the radio's front-end noise, more gain is again detrimental.
-Scott-
toggle quoted message
Show quoted text
Please don't go cutting up the plastic in your PL-380. An antenna that gives a (claimed) 10 dB more gain will make your overload problems worse. Antenna gain simply is not a panacea. Perhaps it would help to know what happens to that gain. When large signals are present, the Si4734 simply "turns down" the gain of its amplifier chain to compensate for the excess gain. Only when all signals are weak will more wideband antenna gain be helpful. Even then, loopsticks contribute substantial noise of their own to the signal. Once the loop's noise exceeds the radio's front-end noise, more gain is again detrimental.
-Scott-
--- In ultralightdx@..., "Stephen" <pianoplayer88key@...> wrote:
Hmm... sound interesting... so maybe we could fit a decent-sized ferrite inside there. I do share his concern about the internally generated noise, too, though. I wonder if it might be possible to fit 2 AAA batteries in the area where the built-in bar is (cutting plastic as necessary), and put a 4"x1/2" or 3"x3/8" Amidon-61 bar in the battery compartment?
But then there's also still the issue of making it usable in vertical orientation. I wonder if there's a place to put, say, a 2"x1/4" or 3"x3/8" Amidon-61 bar on one side of the radio, with a switch to select between the two antennas? It would be kind-of awkward to put the radio in my pocket (for carry-around hands-free use) in horizontal orientation.
http://picasaweb.google.com/PianoPlayer88Key/GrundigG8TypicalUse?authkey=Gv1sRgCIrn_5Pbj_6nKQ#5374564183454699378
That's actually a Grundig G8 that I had bought from Radio Shack, then returned, before I got the PL-380, but it's the same size, basically, and you can see that it isn't exactly a very pocketable radio. I am able to get it in there, but it looks (and feels) a bit awkward. If I could use it vertically without sacrificing more than a couple dB of sensitivity, it would be nice.
--- In ultralightdx@..., D1028Gary@ wrote:
Hello All,
Noted UK experimenter Graham Maynard has published an excellent PL-380
modification article in the April edition of Medium Wave News (Europe's
premier MW hobbyist club bulletin). He details an effective "stealth" loopstick
modification (with some minor plastic removal) and simple component changes
to greatly improve audio fidelity.
Reprinted with Graham's permission, the article has been uploaded to the
Ultralightdx file site at
_http://f1.grp.yahoofs.com/v1/0JHKSyBSe64gJsKLlKJxajGvyDP8imUye-iNYa32zQ_OI350X_pXOaqxuX_6omKENZyVBfJjibSAcarJn_Faqq0PGjemBgc/6
%20Alignment%20%26%20Modification/The%20Tecsun%20PL380mod.doc_
(http://f1.grp.yahoofs.com/v1/0JHKSyBSe64gJsKLlKJxajGvyDP8imUye-iNYa32zQ_OI350X_pXOaqxuX_
6omKENZyVBfJjibSAcarJn_Faqq0PGjemBgc/6%20Alignment%20&%20Modification/The%20
Tecsun%20PL380mod.doc) ,
and is also available at _http://www.mediafire.com/?oy4cqzungkz_
(http://www.mediafire.com/?oy4cqzungkz) .
Graham has been an active UK experimenter for many years, and his fine
technical articles are posted on his website at _http://www.gmweb2.net/_
(http://www.gmweb2.net/) . Thanks to Graham (and MWC) for making this article
available.
73, Gary DeBock (in Puyallup, WA, USA)