I signed up here just to reply to this great (the only one I could find on the internet) question/experience that helped me with an identical problem. I was so close to giving up when I read this thread and went to examine the component that looks like a coin battery (as the original poster described)
and having owned a sucking hakko soldering gun, i ...
You could use a headset or earphones with the receiving radio, so the received audio goes straight into your ears instead of to the microphone of the transmitting radio. Or you could use an assistant to take one radio to another room for your communications tests.
One of the functions of an oscilloscope is actually to measure RF volts, just make sure to use the x 10 function to minimize loading on the circuit you are measuring, and keep in mind that some high impedance circuits will still be affected even if you use the x 10 function.
This is an Inrush Current Limiter (ICL). You can still get them today, but they look quite a bit different. See Digikey for a wide range of parts. Typically, these are used for reducing the inrush current of main power supply capacitors instead of filament protection, so they're optimized a bit differently.
If measuring a circuit output that expects a load impedance, such as a 50 Ohm coax or antenna, then to measure the RF voltage at that point with an oscilloscope, you should terminate that circuit output with the expected impedance (a dummy load), and measure the voltage waveform across that impedance load with a much higher impedance probe (x10 or ...
my Tecsun PL-660 hadn’t been used for a while. It didn’t charge the batteries either. I put the batteries in a separate charger and brought them up to full charge. Still no joy with them in the radio. Occasionally the display came on but not clearly and with various segments missing. Over the course of a few weeks and after a little research I removed the ....
I know this is old, but my friends recommend Troy Radio. They are an authorized FlexRadio shop and specialize in the 5000. You can reach them at:
Link: Troy Radio
I am not associated with Troy Radio nor ever used their service, but have heard they are good.