Heathkit IG-102

[charokeeroad]

Hello Everybody, I'm having trouble getting a modulated signal out of my Heathkit IG-102. Recently purchased on ebay the tester although looking good on the outside was really tared up on the inside. The RF select switch was frozen solid and had to be disassembled and cleaned in order to rotate the Detent switches were black. I did a lot of cleaning and circuit comparing against the schematic and got the RF output to work well but I can't seem to get the AF modulated signal out to work.


I took some photos of the Oscope where I expected to see modulated signals see attached. I see modulation in the first to photos it just doesn't show up at the "internal modulated AF out" BNC jack . The photo numbers are posted on the schematic. If someone is familiar with this signal generator and can direct me to a fix I'd appreciate it.

Both tubes tested good. All the switches are set as directed on the schematic. The internal mod AF out switch is set to internal mod AF out.


Thanks

[bandersen]

It looks correct to me. The "internal modulated AF out" puts out the AF signal used to modulate the RF.

[N2IXK]

I agree, that's how it is supposed to work. In the "Internal Mod AF out" position, you should get an audio signal out of the jack, of 1 kHz or whatever frequency they use.

In the "Ext Mod" position, you put a signal IN through the same jack, and modulate the carrier with it.

[charokeeroad]

Ok, I guess I was confused. I thought the output signal from the "Internal Mod AF out" BNC jack was a modulated signal. If I understand correctly it's a signwave without modulation and that's what I have.

[charokeeroad]

With some adjusting of the scope and the signal generator I am able to get this signal on the scope. My probe is attached to the back of the BNC connector and ground. The Signal generator switch is set to "internal Mod AF out" If this is correct then it must be working.

Thanks

[old_tv_nut]

Your point #1 and the "RF out" BNC are the where the RF modulated by the internal audio frequency exist, as shown on your scope waveform. "MOD" on the control panel stands for "Modulation", not "modulated."

So, as stated above, the EXT MOD IN AF OUT is either external AF in or internal AF out.
Maybe they should have used a slash to indicate "or":

EXT MOD IN / AF OUT

[charokeeroad]

That's helpful. I think I'm getting it.