Heathkit Cheyenne

[N2DTS]

I started work on a Cheyenne I got a while ago, it looked like a nice effort from Heathkit.
Sort of like a dx60 without a power supply but with a built in HA10? vfo.
A reasonable design, 6au6 vfo, 6cl6 buffer/doubler, 5763, 6146 output, with the 12ax7 and 6de7 screen modulator setup, and a oa2 regulator for the vfo.
Push to talk and a TR relay built in.

Nice looking, well built for the most part, a lot of metal in the thing.
Tight design, like a puzzle, to get at that, you have to remove this, take that off, pull that out.

I am trying to fit the QIX modulator setup in the very small space.
I remember why I like home brew so much, I make things with plenty of space.

The one odd thing in the design is the loading cap is located in the audio section....the shaft that drives it runs smack through the entire audio section...

[N2DTS]

Got it done, and it surprised me by working.
I got the radio off ebay and never tested it, the outside was a bit rough, inside had some rust around the tube socket mounts.
Well, its spot on frequency, tunes very nicely, the vfo seems stable as a rock, and the radio puts out 50 watts.
With the wa1qix modulator installed, I adjust it for 25 watts carrier and it does 100 watts pep, out of a single 6146 with no color showing.

One problem, the radio uses 12 volts AC to power the PTT which gets into the d104 like mad, got to change it over to DC.


https://n2dts.smugmug.com/Ham-radio/i-8h4Nz9J/0/L/PC100350-L.jpg

[K6JEK]

Congratulations on reviving the Cheyenne. A few years back my neighbor Jeff, K6JCA, brought one back to life and noticed some oddities. The schematic was different from the assembly manual. There were some problems running it as assembled. You might find his blog on the subject useful:

http://k6jca.blogspot.com/2010/01/revisiting-heathkit-cheyenne.html

Would love to see more pictures. What is the QIX modulator?

[kc4umo]

Good job bring the piece of history back to life.

[WA5VGO]

Check it for FM on 40 meters when using the VFO. This is a common problem (just as it is with the Johnson Ranger).

[WD5JKO]

A good reference on the Cheyenne is from kj6ca. He notes several schematic / build errors, and does some mods. One mod is DC to the PTT circuit.

http://k6jca.blogspot.com/2009/12/improving-am-performance-of-heathkit-mt.html
http://k6jca.blogspot.com/2010/01/revisiting-heathkit-cheyenne.html

Jim
Wd5JKO

[N2DTS]

I used a diode and cap to change the relay to DC and it reduced the hum quite a bit.
There is still some power supply hum.

Its very interesting I can get 25 watts carrier and 100 watts pep out of this thing.

[N2DTS]

Did more tests and added the diode and cap to the PTT relay.
Too much high voltage going into the radio from the drake supply, 730 volts, but not enough on the low voltage, wants 300 and the drake gives 250.
Still, the radio works great and is very stable, things just arc and spark on key/unkey.

I would need to make a power supply for the radio.
These screen modulated rigs like a nice choke input well filtered suppy since there is nothing to limit the low frequency response at all. No inductance of a mod transformer in the B+.

I ran the filaments off a 30 amp 12 vdc supply and still had some hum on the audio.

Cap input supplies do not work well, nor do voltage doublers which are cap input.