Heathkit DX-35?

[VE3GZB]

Any thoughts, experiences, warnings?

Looks like I might be able to get one soon! Maybe I'll finally be able to be heard?

73s
geo
VE3GZB

[W3DBB]

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[VE3GZB]

I was planning on replacing the tube rectifier with a S.S. set of diodes anyway for reduced heat and improved voltage regulation, I have enough to do that.

What does the B+ on the 6146 run at normally in this rig? I might be able to scare up another power Xformer if the OEM unit isn't up to snuff?

73s
geo

[SA7AUY]

The plate voltage is 600V.
The circuit diagram for the DX-35 is here on my web site: http://www.heathkit.nu/heathkit_nu_DX-35.html

[VE3GZB]

Thanks! I got the DX-35 today and I'm now leaving it on the bench, slowly applying DC (I have one of those 0-500V Heathkit power supplies) to allow the electrolytics to reform. I'd prefer to leave the originals installed and in a reformed state than mess around with trying to replace them.

The power Xformer is in good shape, no opens! I plan to leave the 5U4 installed, just cut one of the fil. leads and install a few 1N4007s beneath the chassis.

What sort of mic is it designed to mate with? What output level I mean? I have a couple of loudspeakers (small ones) I can use as mics, would they work?

73s
geo

[N2DTS]

The scematic tells you, a 10 meg input resistor says the rig wants a very high imp d104 type microphone.

Included in the boxes I sent is a transformer, 50 and 600 ohms to 50K ohms which might help.
If you have a radio shack, they used to sell little electret condensor mic elements that sound good for about $2.00.
Or you could rip one out of an old phone or something.
A speaker will sound incredibly nasty.

Brett

[Ed/KB1HYS]

Mouser has crystal mic elements for cheap cash. High impedance, and nice response.

Some guys have used them to repair D104s that had bad elements with good reports.

[SA7AUY]

The manual says that the microphone should be of crystal, ceramic or hi Z dynamic type.

[VE3GZB]

Thanks! I have salvaged Piezo elements out of alarm buzzers from here at work, the electronics in the buzzers fail over time but the piezo elements are ok still. I'll use one of them as a mic!

Does anyone have any Xtals for 40m they can spare for this unit? It came with only 1 Xtal for 80m, I'm not having any luck running it at a doubler?

73s
geo

[Ed/KB1HYS]

Try those piezo elements into the scope first. See if you actually get some type of audio voltage output. They might work.  I know of a fella that used the piezo element out of a cigarette lighter to make a high impedance speaker for crystal radio so I guess the concept is sound.

You should look at a set of books called The Impoverished Radio Experimenter by Lyndsay publishing. I've got a volume or two and they do stuff like this through out.

a salvaged mic from an older telephone set would probably be better.

[N2DTS]

I think it would work poorly, worse than the speaker idea.
Because its designed to produce a loud and very high tone, it will likely will be very insensitive and only reproduce high pitch noises.

You want someone to come back to a cq, dont you?
You need to sound reasonable, not like a screech owl...

Brett