Heathkit IT-11 function videos - Page 1
Forum section: electronics / testgear

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 01, 2015, 02:44:58 am
content: Here are some videos I made with my Heathkit IT-11

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 01, 2015, 03:00:19 am
content: Fantastic, thanks for sharing!That magic eye really is groovy...

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 06, 2015, 11:58:11 pm
content: https://youtu.be/mK_P1MEHfu8

author: joeqsmith
author_rank: Super Contributor
timestamp: November 07, 2015, 05:37:45 am
content: Very nice. What's the max current and test voltage?

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 07, 2015, 01:34:22 pm
content: Hello,The max test voltage setting (no load) is 600VDC. The current limiting is about 2.2ma (2200ua)

author: Radio Tech
author_rank: Frequent Contributor
timestamp: November 07, 2015, 02:00:07 pm
content: Thanks for sharing.I have the IT-28. In need of a restore and on the list when I can get around to it.

author: Cubdriver
author_rank: Unknown
timestamp: November 07, 2015, 03:56:47 pm
content: Can you successfully re-form a paper cap? I know it can work with old electrolytics that have been idle for long periods and have had their oxide layers dissolve (provided of course that they haven't dried out), but didn't think it could work on paper caps. I have had some good success re-forming electrolytics on a Sprague TO-3, and have a Heath IT-28 on the shelf awaiting attention.-Pat

author: joeqsmith
author_rank: Super Contributor
timestamp: November 09, 2015, 04:07:49 am
content: Quote from: jcrubin on November 07, 2015, 01:34:22 pmThanks. I found the manual for it online and plan to read it.http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_IT-NE/IT-11/IT-11.pdf

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 09, 2015, 01:44:15 pm
content: Quote from: Cubdriver on November 07, 2015, 03:56:47 pmThe short answer is no......Ive been doing some tests with paper caps and have documented over time smaller currents and lower voltage drops over time just like an electrolytic. It is however an extremely limited change over time and ive found that after a short time, the original condition is observed again.Since the voltage went up as the current dropped in these scenarios (circuit was less loaded down) the internal resistance of the capacitor must have increased over the given time. My assumption is that the small current flow affected (however slightly) the internal temperature of the paper cap which changed its characteristics (increased resistance), and made it look like the cap improved, which is lost once cooled down.

author: SeanB
author_rank: Super Contributor
timestamp: November 09, 2015, 06:16:53 pm
content: Paper caps fail by adsorbing water from the air, and the only way to drive it off is to heat them up to vapourise the water. The issue is the temperature required to drive water out of the paper where it is chemically bound is higher than the rest of the capacitor, like the soldering and the wax encapsulation, can withstand. The only solution is to replace with a new polyester or polycarbonate film unit, unless you have a vacuum chamber that you can use for a month to dry them out at 70C. Even then they will immediately start to absorb water again.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: November 09, 2015, 06:22:11 pm
content: I never try and save the old paper cap. I always replace them. They will not survive.On the other hand I have some folks that like to keep their vintage pieces stock looking. If that is the case I heat the paper cap and pull the insides out. When you heat the outside of the cap and the wax runs off it looks practically new. I stuff a new cap inside and seal the ends.

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 10, 2015, 01:43:26 pm
content: Quote from: SeanB on November 09, 2015, 06:16:53 pmIts quite possible that in running the current through it, the heat did remove the moisture to some degree and allowed for increased resistance. With the old paper ones, id wonder if any of the moisture left the capacitor or was simply displaced within it.

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 15, 2015, 02:07:07 pm
content: Here is the last video. Overhaul , calibration and testinghttps://youtu.be/Y_sx3oh72DA

author: Radio Tech
author_rank: Frequent Contributor
timestamp: November 15, 2015, 02:27:00 pm
content: Very Nice.Good to see it works properly.I need to rebuild mine also.