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Heathkit IG-102 RF Signal Gen - Printable Version

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Heathkit IG-102 RF Signal Gen - klondike98 - 07-06-2015

Picked up a Heathkit IG-102 RF Signal Gen and have started to check it out.  Here’s the schematic link.  Someone had cut some of the resistors out of the RF output circuit but I have no idea why.

[Image: https://www.dropbox.com/s/pngawjvlpexny3s/ig-102_RFout.jpg?raw=1]

There is also a strange item that I don’t understand and doesn’t seem to be on the schematic.  Below is a pic of the circuit where the 680 resistor in question is located and a pic of the resistor with a wire wrapped around it.  I was thinking it might be something like the gimmick wire in Philcos but this wire is looped around the resistor AND soldered to BOTH ends, essentially taking the resistor out of the circuit.  What’s with that????

[Image: https://www.dropbox.com/s/89ovt749bggtu3h/ig-102_680pin6V2.jpg?raw=1][Image: https://www.dropbox.com/s/7gy0lgb1mogprvd/ig-102_schematic2.jpg?raw=1]

I’m getting 400Hz out of the audio modulation and I can faintly hear an AM radio catch the RF leakage from the unit as I tune through the frequency on the radio so its working, at least to some level.  Unfortunately I don’t have a scope to actually look at it.

RE: Heathkit IG-102 RF Signal Gen - Radioroslyn - 07-06-2015

Looks like a parasitic  suppressor. with out the resistor there's no HV on the output tube hence no output. Without the small coil ( looks like 6t of 18ga or so) the output could generate very high frequency oscillations that could damage the tube. That coil acts as a small choke to prevent the vhf oscillations.
You moved!!! Your not in Pa.

Terry

RE: Heathkit IG-102 RF Signal Gen - klondike98 - 07-06-2015

Thanks Terry. My electronics understanding is pretty limited but I don't see how the resistor is doing anything since the coil shorts across the resistor.

When I retired we got a small place in Oregon to spend some time at. Am there at the moment so changed my location on the profile.

RE: Heathkit IG-102 RF Signal Gen - Carl Travis - 07-06-2015

Bob,
Do you have a copy of the assembly manual?
http://gmcotton.com/ham_radio/misc%20manuals/Heathkkit/Heahkit%20Signal%20Generator%20IG-102%20Complete.pdf

RE: Heathkit IG-102 RF Signal Gen - klondike98 - 07-06-2015

Yes but thanks for the help! Unless I missed it I didn't see anything about wrapping the choke around the 680 ohm resistor so it must have been an add on.

RE: Heathkit IG-102 RF Signal Gen - klondike98 - 07-07-2015

Continued to try to get this to work properly and decided to take out the funky 680 ohm resistor with its added on choke. Someone had to have added that little feature at some point for some reason because when I took it out and replaced with normal 680 ohm resistor all is now working as I expected.  Signal is stronger and comes out the RF output as it should rather than just some leakage.  Can hear loud 400Hz tone as expected on tuned in frequencies. Will call it done and begin using it for alignments.

Pesky  Icon_evil part:

[Image: https://www.dropbox.com/s/alj08261jko0pk4/ig-102_funky%20680%20resistor.jpg?raw=1]

RE: Heathkit IG-102 RF Signal Gen - codefox1 - 08-01-2015

Agree, makes no sense to wind a couple of turns around a 680 ohm resistor for vintage testers.