Vintage Heathkit help

[Burt]

This goes back to the mobile days of the early 60s
I have an HR-20, HX-20, and HP-20 and cannot figure out how to hookup the 8 pin output plug/jack to the 11 pin jack of the receiver.
I have the necessary plugs but the color code in the manual does not apply to the cables I have

[WD8BIL]

Forget the color coding.
Use the plug pin numbers for reference.

[W1RKW]

I'm baffled by the filament voltages and the 4 or 5 pins related to the filament circuit.  Pins 6 and 7 seem to be able to accept AC filament voltage yet the receiver schematic shows a filament voltage regulator which implies DC. Additionally, V1 and V2 tie back to the socket. Not sure what should be used here. Why the filament regulator?

The receiver requires 350V and the PS provides 300V.  Don't know how critical this is but pins 3 match.

The 600V isn't needed but having it float unloaded may not be a good thing to do.

Then there's the matter of ground. Pin 6 of the receiver shows ground.  Can pin2 of the PS be tied here? Not sure.

[KA8WTK]

Burt,
  The information you need is in the HR-20 assembly manual.
  Mods.dk has the manual for free download. You do need to create a free account there. I use them for manuals I don't have.
  Also, Pete probably has a very good copy available from his commercial site. I have used these as well; very nice and readable.

Bill KA8WTK

[AB2EZ]

Burt

Here are some additional suggestions:

1. For the cable between the HP-20 power supply (8-pin male plug) and the HX-20 transmitter (8-pin female plug):

As per the earlier post, just wire the plugs together on a pin-to-pin basis (i.e. pin 1 to pin 1).

Note: Only 6 wires are needed for this cable, because there is no connection on the power supply side to pin 8 or to pin 5

Note: In the schematic of the HP-20 power supply there are three jumpers shown. Use ONLY the "12.6V -4A" jumper. Make sure that the two 6.3V 8A jumpers are not installed.

Note: In the schematic of the HX-20 transmitter, on the lower left, there are two alternative ways shown for wiring up the filament bus terminal strip. Make sure that your HX-20 is wired using the "12-volt" configuration.

Once you have this cable completed, the "12.6V-4A" jumper installed in the HP-20, and you have ensured that the HX-20 filament bus terminal strip is wired for the "12-volt" configuration, you should do the following:

Plug in the power supply, turn it on, and verify that the voltage between pin 6 and pin 7 on the output connector is approximately 12.6V AC. Turn off the HP-20 power supply, and wait a minute for the capacitors to bleed down. Then connect the HX-20 transmitter to the HP-20 power supply, using your new cable... turn on the HX-20 and the HP-20... and do some tests to verify that the HX-20 transmitter is working properly.

2. For the cable between the HX-20 transmitter (8 pin male plug) and the HR-20 receiver (11 pin female plug):

You will need 6 insulated wires, a short piece of wire to make a jumper, and a 51 ohm 1 watt (or larger) resistor.

These wires are also installed, as indicated below, pin-to-pin between the plugs (e.g. pin 1 of the 11 pin plug to pin 1 of the 8 pin plug)

On the 11 pin female plug side, you may want to refer to the instructions on page 49 of the HR-20 assembly manual. Note that the "black" and "brown" wires that are shown on page 49 of the manual, connected to the receiver side's 11 pin plug will not be connected to the transmitter side's 8 pin plug in this base station configuration of the HX-20 transmitter, HR-20 receiver, and HP-20 power supply. That is why you only need 6 wires in this cable. I.e. you won't be using the "black" and the "brown" wires, shown on p49 of the manual, to connect to the HX-20 transmitter... or for any other purpose. [Note that the HR-20 schematic shows a 6V voltage regulator (a Zener diode and a pass transistor) connected to pins 8, 9, and 10 of the 11 pin socket... as pointed out by W1RKW. As per the manual, this voltage regulator is not used in this base station configuration. It is used only when the HR-20's filaments are powered by 12V DC in a mobile application. In the 12V DC mobile application, this voltage regulator provides regulated 6V DC to the filaments of tubes V1 and V2, in parallel]

Install a #20, or larger guage wire jumper between pin 2 and pin 7 of the 11 pin plug (or, to make things easier, install this jumper inside the HR-20 between pin 2 and pin 7 of the 11 pin socket).  

Install a 51 ohm 1 watt (or larger) resistor between pin 7 and pin 11 of the 11 pin plug (or, to make things easier, install this resistor inside the HR-20 between pin 7 and pin 11 of the 11 pin socket). The purpose of this resistor is to equalize the voltages across the 6.3V filaments of V1 and V2, which are being powered in series in this base station configuration.

For each connector the 6 wires should be connected as follows:

Green (500 ohm HR-20 receiver audio to HX-20 transmitter anti-VOX): to pin 1 on both sides
Orange (+300V): to pin 3 on both sides
Yellow (one side of the HR-20's audio transformer's speaker output): to pin 4 on both sides
Blue (one side of the HR-20's  J2, i.e. the HR-20 jack that the speaker connects to): to pin 5 on both sides
[Note, the purpose of the above yellow and blue wires is to allow the HX-20 to disconnect the HR-20's speaker during transmit]
Red (non-grounded side of the HR-20 receiver's filament bus): to pin 6 on both sides
White (HR-20 ground, also connected to grounded side of the receiver's filament bus via the wire jumper between pin 2 and pin 7 of the 11 pin connector): to pin 7 on both sides

Stu

[Burt]

I will try suggestions and get back to you, THANKS!

[n1uvi]

maybe this will help