Re: Comparing ferrite loopsticks a box loop on longwave


Barry M Gelb
 

Rick,

Are you saying that the PL-606 has a built-in external MW antenna jack like the vertically oriented Pl-360 or that it needs modification like the PL-310's jack.

Thanks,

Barry

--- In ultralightdx@yahoogroups.com, "w4dst" <w4dst@...> wrote:




My understanding is that the Tecsuns use a varactor (variable >capacitance) to tune the internal ferrite to the desired frequency. >This tuning process occurs every time you adjust the tuning knob, in >which case the receiver valiantly hunts for the optimum varactor >setting. This is a neat trick, allowing for enhanced sensitivity.
Not all Tecsuns, only the Tecsun receivers, and Grundig G8, using the Si4734 IC have this built-in varactor which is one of the best features of the chip. The inability to use an external MW antenna in a stock SI4734 based Tecsun or G8, PL-606 excepted, is a serious shortcoming. I've been able to tune a 24" square spiral loop, a 60 year old loop antenna from an old Zenith AM/FM radio, and several different ferrite bar antennas easily with my modified PL-380 and PL-310 using the internal varactor in the Si4734. As long as the impedance is within the chip's specs, the radio will tune it with no external capacitor needed.

Maybe Tecsun will start including the ability to use an external MW antenna in future radios like they have in the PL-606.

Rick W4DST

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