I’ve been a bit sceptical about the balance of the military telephone cable called DL1000 in Sweden. It almost looks as if one wire is wound around the other rather than two twisted wires. So I made a measurement as outlined in the sketch below while listening on strong signals:
As reference I connected both wires in parallel connected directly to the measurement receiver.
The results were:
Frequency Common mode rejection
7 MHz 25 dB
3.5 MHz 40 dB
There was no difference with and without the load resistor R.
So the telephone line is OK as a feeder for receiving antennas on 80 and below as regards to common mode pick up but doubtful on 40m.