The AM Forum

Hello all,
I have a DX-60A carcass with a good power supply.
I'm going to use the PS for another project. My question is, the transformer was removed and I'm not 100% sure of what two wires are for the primary windings. Logic tells me the two black wires, but this is after all a Heathkit product.
I have a manual for the DX-60B but it is a different transformer. Can someone please give me from the "A" models manual, the info for the windings?

Thanks es 73
Dan, N8IE

  The DX60 manual—no "A" or "B" specified— is available on the web, like here, for example:
https://www.manualslib.com/manual/1021114/Heathkit-Dx-60.html?page=2#manual
  It appears that one of the differences between the A and B models is that the A didn't have the dual-primary transformer, for either 120v or 240v service, that the B model had. In the case of the B model, one primary wire was solid black, with green, yellow, or red tracer stripes on the three other black wires to indicate which primary winding they went to. The schematic for the A model doesn't indicate the colors, but the text of the manual seems to imply that both primary wires are solid black.
  A useful trick when when uncertain about primary connections: use a variac to "tickle" the winding in question with just a little AC, like 5 or 10 volts (monitor the current to keep it safe in case you're on the wrong wires) and measure the voltage on the secondary. Assuming that you know what the transformation ratio is, just do the math. If the secondary is supposed to deliver 600v with 120v on the primary, that's a ratio of 5, so putting 10v on the primary will get you 50v on the secondary, and so forth.
  One thing about Heath schematics and manuals that always annoyed me is that the parts list only gives the values and the Heath part number, but doesn't correlate those part numbers with the reference designators on the schematic.

Thanks for the reply, good info.
Heathkit manuals really lacked in that area, I guess they wanted to keep you buying their parts.it bites now because replacement parts are scarce.

73
Dan, N8IE

Dan,

Here is some info from the ARRL and RF Cafe:

Black wires are usually 120V primaries.

Green wires are usually 12.6V, and the center tap usually Green/Yellow, so between the Green/Yellow and any other Green will be 6.3V

The Reds are usually the secondary voltage of 260V.

The other colors would most like be the bias supply of 110V.

https://www.rfcafe.com/references/electrical/xfr-lead-color-code.htm

Well I broke out my VOM and did some investigating. Here is what I found, the following wires have continuity, voltages are unloaded:
Black wires pair, primaries.
Red wires pair, 260vac.
Brown wires pair, 110vac.
Yellow/Y-G pair, 7vac.
Blue/Y-B pair, 7vac.

Now in the schematic, the windings for the filament voltage are center tapped, one half 6.3vac is used for the filaments while the other side goes, also 6.3vac goes to the accessory socket of the DX-60A.

So I'm going to assume this is either a replacement transformer or a difference between the schematic and what's real.

So I think that clears things up, I'll just have an extra set of filament lines hanging.

I'd say you are on to something useful Dan.

The original DX-60 used dual filament windings, one fed the DX-60 and the other was brought out to the VFO socket.  Maybe they used the leftover transformers in the early A model production.

One side of each of the separate windings is grounded in the DX-60 so I guess you could call it an external center tap :)

Rodger WQ9E