CABLES/CONNECTORS
The Heathkit manuals are of course excellent and should be referred to both for wiring instructions and detailed explanations of how the circuits work.
There are 4 cables associated with the HA-14:
1) The coaxial antenna cable: Little needs said about the antenna cable except to remember the HA-14 does not have a Loading control; only a Tuning control. The loading is set at a fixed 50 ohms. This does not usually cause a problem as long as the antenna is properly tuned and shows a low SWR to the amplifier.
SWR is turn is not usually a problem with an ordinary dipole fed by matching ~72 ohm coax, or a beam or vertical or other antenna matched to a ~50 ohm cable. The problem may arise using a mobile antenna which can exhibit a wildly varying SWR depending on care in tuning, by movement in the wind, or tuning the transmitter to a frequency outside its narrow bandwidth.
I have experienced no problems running full SSB power to
either RG-58 or RG-59.
2) The Low Voltage and Control cable: This cable carries the ON/OFF switch control, 12 volt filament power for the 572B's, the line that controls the antenna relay, and another for the ALC circuit. The connectors for this 8 conductor cable are different for the AC and DC power supplies.
AC supply cable: ............ (pics)
DC supply cable: ........... (pics)
3) The High Voltage Cable: ...... (pics). A separate cable made of "spark plug wire" is used to carry the high voltage from the power supply to the amplifier. Since cables deteriorate with age, it should be inspected carefully before use, and probably be replaced after a few decades of use.
4) Transmitter-Amplifier Cable: Hooking most tube type Heathkit Transmitters/Transceivers of that era to the HA-14 is a piece of cake. They are designed to work with each other. Just follow the cable wiring instructions in the manuals.
But hooking any modern solid state transceiver to any sparky old high voltage tube type amplifier should cause a moment of pause. There are more than a few reports of blown transistors when such a connection is attempted.
There are several solutions to this potential problem. They involve isolating the two electrical systems, usually by a relay of some sort.
One solution is to use an "Amplifier Interface" of the sort made by Ameritron. This involves a separate box which goes between the units. Download their users manual for useful information on interfacing.
Another solution is to use a custom cable which includes a relay built into one of the connectors. K8TJ builds and sells such "amplifier relay cables". He sent along some interesting comments and opinions on this subject which you can read here.
