I have a Tecsun PL-660 (link is to the manual) has the usual AM/FM radio telescoping internal antenna, and a 1/8th-inch jack for an external shortwave antenna. There appears to be no facility for attaching to station ground, unless one of the terminals in the 1/8th inch jack can be attached to a station ground. It has USB/LSB single-sideband modes, as well as AM reception and pretty good general coverage from about 3200 khz up, in AM and SSB, plus commercial AM/FM and air-band coverage.
My question is: It stands to reason I should get better reception on the 80 meter, 40 meter, 30meter, 20meter ham bands if I build a proper dipole for each, and manually switch them out. With better quality non-portable amateur radio receivers and transceivers there appears to be a way to ground the radio. Perhaps one of the pins on portable radios is also possibly the station ground pin? Does anybody ground their portable radios when using them for Shortwave listening?
I have lost the little bit of wire attached to a headphone jack as shown in the picture here, that makes up the provided shortwave listening antenna:
I'm about to experiment and see if I can't get good reception with a home-made replacement, or rather set of replacements, but as dipoles instead of just random-wire.
What I think I know is that:
That for a particular shortwave band, a dipole for that frequency will be resonant and will thus be ideal for receiving that band.
A coaxial feed, with the jacket of the coaxial feed attached to station ground will be good.
That it won't take long to figure out which terminal (pin) in the 1/8th-inch 3-pin connector is for the actual antenna.
Things I don't know:
a. What the impedance of the radio tuner is.
b. What else can be done if I want to improve overall reception quality.
c. I intend to just experiment with wiring up the dipole to the two pins on the headphone jack but I have no idea if the little portable radio is likely to even have both pins connected inside the radio.
Has anyone ever made their own antennas for little portable AA battery receivers like the Tecsuns (or Grundigs or other similar units)?