Help repairing old Heathkit RF signal generator IG-102  - Page 1
Forum section: electronics / repair

author: heathkitman
author_rank: Contributor
timestamp: December 30, 2014, 01:04:27 am
content: Hi , I'm looking for some guidance to try to get my old Heathkit RF signal generator IG-102 back up and running for nostalgic reasons. It was in storage for about 30 to 35 years. I replaced a few of the caps, as needed, and the tubes. The test voltages are now correct and unit is basically working but I have the following two issues.The AF output is 340 Hz instead of the specified 400Hz.The main problem is there's very little amplitude to the RF output. You have to have the attenuation turned up to maximum output to be able to detect any signal at the RF output BNC.Any help would be greatly appreciated.http://www.heathkit.nu/IG-102_schematic_1600.pngThanksheathkitman

author: N2IXK
author_rank: Frequent Contributor
timestamp: December 30, 2014, 01:18:42 am
content: The 400Hz was only a "nominal" frequency. Check the cap values (C13-C16) around T2 to see if they are within tolerance. Check all the carbon comp resistors in the unit for drift, as well.Do you know if the unit ever worked properly? Assembly errors are MUCH more likely when dealing with kit assembled units.

author: heathkitman
author_rank: Contributor
timestamp: December 30, 2014, 01:23:11 am
content: The unit was functioning properly when it was put into storage many years ago. It was assembled by one of the technicians that maintain the equipment at the USNA lab for 30 years.

author: xwarp
author_rank: Frequent Contributor
timestamp: January 01, 2015, 10:48:37 am
content: Here is something you may want to consider:http://km5z.us/blog/?p=67I plan on doing that with mine.

author: Seekonk
author_rank: Super Contributor
timestamp: January 04, 2015, 06:01:16 am
content: I have one of those I bought for a friends kid who lost interest in electronics before I could fix it up. Mine was wired beautifully but at the higher frequencies wouldn't oscillate. Adding extra bypass caps and other tubes wouldn't fix it. Set it aside for years since I have plenty of other generators. I also thought about converting it to FET operation so I could use it at my camp which is only 12V. That article is inspiring me.

author: N2IXK
author_rank: Frequent Contributor
timestamp: January 04, 2015, 03:21:51 pm
content: I worked on a similar vintage and quality unit (Eico, IIRC) which refused to oscillate on higher bands unless it was installed in the case. Made trimming the frequency rather frustrating...

author: steve_w
author_rank: Regular Contributor
timestamp: January 06, 2015, 05:06:37 am
content: If it used to work, something has changed, if the voltages are good it looks mechanical.Check the switches, give em a good clean and check continuity with a meter, it might throw something up.regardsSteve W

author: oldway
author_rank: Super Contributor
timestamp: January 06, 2015, 06:39:45 am
content: Replace:C17 : 0.01µFC20 : 0.01µFTest tubes if you can or replace them.Check power supply for ripple.

author: Rory
author_rank: Frequent Contributor
timestamp: January 06, 2015, 07:03:25 am
content: Concur with Oldway. Also check C22 and look for cold solder joints in the signal path.

author: Cyberdragon
author_rank: Super Contributor
timestamp: January 06, 2015, 08:19:13 am
content: Did you change the HVDC filter caps? Check the tubes but don't change them unless you know they're bad or else it could uncalibrate. They won't go bad unless it was abused.

author: oldway
author_rank: Super Contributor
timestamp: January 06, 2015, 03:22:54 pm
content: Quote from: Cyberdragon on January 06, 2015, 08:19:13 amDon't worry about calibration !Change the tubes to see if it solve the problem. If not, use the original tubes again.This was a commun procedure with tube color TV sets, never had problem with this !Calibration procedure is easy to do if necessary.I have an old tube TV - FM Sweemar generator model LSG-532 LEADER and it is still working very well.