Hi Julian,
the schematic you can find on the web is not fully accurate anyway it is
pretty close to the real circuit. About the DE1103 trick (I suppose you mean
the firmware "bug" that can be forced to occur by operating the keyboard,
etc.) I don't know if something similar can be found on PL-600 (never read
anywhere on the web). The firmware is different w.r.t. DE1103, the controls
are different but...you never know :-)
In my opinion the soldering iron would be still helpful to reduce the gain
loss at lower frequencies which is caused by the 10uH inductor on the source
of the input JFET (this impedance buffer sits between the LPF and the
mixer). I can't see C88, C96 and C97 on PL-600, anyway please I'm very
interested in your reasoning for getting a result of 75 ohms, please could
you kindly clarify?
Best regards
Daniele
----- Original Message -----
From: "Julian Hardstone" <[email protected]>
To: <[email protected]>
Sent: Monday, March 29, 2010 1:45 AM
Subject: LF: Re: Balun for tuned loop antenna
Daniele - I see from the schematic
http://radio-timetraveller.blogspot.com/2009/08/tecsun-pl-600-review-and-schematics.html
that the
MF-HF input to the PL-600 is a LPF followed by a balanced mixer
Also, I believe that the PL-600 is similar to the earlier -1103 sets, so
maybe the same 'easter-egg
trick' works for the -600 and you did not have to use a soldering iron to
connect an MF antenna..?
If the LPF is the same as the -1103, C88 will be 82p, C96 7p, C97 68p, so
maybe Zin is 75ohm
I managed to enable (by means of the soldering iron :-)) the external
antenna jack also for MF and
LF on PL-600 (normally it only works in HF)...<<<
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