A few comments..
For the ICF-7600, adding external wire might cause more problems than it solves. Portables are usually optimized for the whip and long random length wires can introduce overloading. Not saying it's impossible to improve the performance of this radio with an outside antenna, but it might be challenging.
For the DX-160, it appears that it has a 50 ohm unbalanced (??) antenna input (with screw terminals instead of a newer style connector). It might make sense trying to run coax from the antenna input to a random wire that has some kind of impedance matching transformer. I'm thinking something like this:
http://www.parelectronics.com/swl-end.php
A simple dipole might also do just fine for general purpose listening. If you still find yourself stuck it might be worth investigating how sensitive your DX-160 really is these days. That radio could be upwards of 40 years old and in need of some work.
Thanks, beerus.
I am planning on only using this antenna on the 160 upon which I have done the sensitivity, RF grounding, and audio recap mods on this receiver. I also put a digital freq counter on it. This is what I did (from antiqueradios.com)
2. Use the fiberboard cover off of the rear of radio, as a pattern to fabricate a new cover from sheet metal. I used a sheet of plated steel from the bottom of a discarded video tape player. It had a few nice narrow vent slots punched in it, which I used. Use any sheet steel, copper, brass (roof flashing is great), or aluminum. Choose a thickness from .020 in. (0,5mm), to .040 in. (1,0mm). Venting is nice, but not really needed, as this radio does not produce much heat. Remove any paint from the inside of your metal cover, where the screw holes are. Grounding is the key to effectivness. I did not fabricate a metal shield, just used a quadruple layer of aluminum foil.
3. The new metal back cover will drop the sensitivity of the radio 2-4 'S' units unless the rod antenna bar is moved away from your new cover. Remove the 4 screws that hold the AM rod antenna to the metal chassis. Move the antenna about 1 inch (25mm) towards the radio front, and another 1/2 inch (13mm) to the closest side (left side viewed from back). Use a pencil, and use the screwholes in the plastic stands to mark the chassis. On mine, 2 holes went where the near-middle ridge in the chassis is. Look underneath, and be sure nothing is in the way. Drill new holes (3/32inch or 0,9mm dia.)DON'T GO THROUGH TOO FAR. Re-install the rod antenna in the new place. If you don't want to drill holes, rough up the metal chassis with sandpaper, and use a couple of dabs of a good industrial Epoxy adhesive. Once the rod antenna is secured, replace the top cover and install your new metal rear cover.
4. Now, to improve reception, remove R-2 and replace it with a 5K ohm resistor and a salvaged neon light bulb in parallel. These lights were used in wall switches, nite-lites, toolbox electrical outlet test lights. The original 220 ohm resistor acts as an antenna signal direct shunt to ground to help the protection diodes with static electricity. The neon bulb will short away any static over 60 volts, and the 5K resistor will handle anything below the diode threshold. The 220 ohm resistor killed off about 3 'S' units of signal on ALL bands. I like all the gain I can possibly get.
5. If you listen to the lower frequencies, and find that the antenna tuning capacitor is lacking in capacitance, short out capacitor C77. This capacitor is wired in series with the tuning capacitor, it does nothing but limit the maximum tuning capacitance of the input circuit for the first stage R.F. amp F.E.T.. Shorted out, the tuning will be more efficient, especially on the 'A' band. Some antennas will not need the extra capacitance, so you may not see any change except for the knob changing position for the same tuning effect.
I have not had the tuner aligned as it -seems- to be OK. I think that an alignment cost would provide diminishing returns, but not sure.