Heathkit IM 11 VTVM - Page 1
Forum section: electronics / testgear

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 08, 2015, 10:02:51 pm
content: Hey guys,I've made a few videos of my IM 11 last month. The meter works well, but could be better. The only thing i'd replaced was the 16ufd 150v with a 22uf 160v as well as the .047uf 1600v cap with the same value.Here is a comprehensive listing of all resistor values and the % tolerance. All resistors out of tolerance will be replaced. The top list is 10%, the bottom list is 1%R33,34,and 35 cannot be tested in circuit, however their values are offset by a POT anyway....https://youtu.be/AYgx8VCRBe0https://youtu.be/djrn5aUlF0o

author: Muttley Snickers
author_rank: Unknown
timestamp: November 08, 2015, 11:28:50 pm
content: Many thanks for the great video,,,,Now inspired to know more about the meter I went hunting for the original manual and in particular some more information on the original probe, I'm also not satisfied with the spring battery holder on mine and found a better solution by putting it in a camera film case as linked below.Many thanks and kind regards..MuttleyHeathkit IM-11 and other manuals.http://www.n0trq.com/manuals/heathkit/Modification to the battery holder and input jacks.http://www.heathkit.nu/heathkit_nu_IM-11.htmlMy IM-11 pictures.https://www.eevblog.com/forum/repair/vintage-heathkit-ig-1271-function-generator-troubleshoot-and-repair/msg757530/#msg757530

author: Radio Tech
author_rank: Frequent Contributor
timestamp: November 08, 2015, 11:59:12 pm
content: Thanks for the video. I miss the old IM-11 I used when I worked at a repair shop years ago. I have 4 other VTVM here but none work as good at the IM-11 did. Good meter.BTW, what is that mechanical mod you have there?Also subscribed

author: med6753
author_rank: Super Contributor
timestamp: November 09, 2015, 02:26:31 am
content: I have a V-5 which is the grandfather to your IM-11. I also did a complete rebuild and it works very well.

author: quantalume
author_rank: Unknown
timestamp: November 09, 2015, 03:30:57 pm
content: I love those old VTVMs. Sometimes only an analog meter will do. I still have an IM-18 that I bought new when I was like 14 years old. I recently performed the modification to move the 1 M ohm probe resistor inside so I can use any probe set with it.

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 10, 2015, 01:46:09 pm
content: Quote from: quantalume on November 09, 2015, 03:30:57 pmSo you modified the case for a separate AC / DC input?

author: quantalume
author_rank: Unknown
timestamp: November 10, 2015, 04:09:38 pm
content: Quote from: jcrubin on November 10, 2015, 01:46:09 pmNo, the 1 M resistor is switched in and out by the function switch. I left the existing phone jack in place. I have phone-to-BNC and phone-to-banana adapters that allow me to use common test leads. There are a few disadvantages to the modification. Here is a recent forum thread discussing it:http://www.antiqueradios.com/forums/viewtopic.php?t=131765.

author: jcrubin
author_rank: Frequent Contributor
timestamp: November 11, 2015, 12:35:33 am
content: Aside from staying original. When I use my VTVM:I'm tying the NEG to the floating chassis anyway......I'm measuring something generally high voltage DCThat being said, the original setup works for me.

author: billfernandez
author_rank: Regular Contributor
timestamp: November 11, 2015, 03:12:14 am
content: How fun! I build one of those in high school, and it was my only meter for many years. Good memories.

author: AF6LJ
author_rank: Unknown
timestamp: November 11, 2015, 03:22:45 am
content: Quote from: quantalume on November 09, 2015, 03:30:57 pmFor general DC and low frequency AC measuring that is not a bad idea.Having the resistor in the probe is actually better all around.What some have done is make up sets of leads with the 1 MEG resistor in them and not there for for ohms and AC.One thing I learned shortly after building the Heath FET multimeter is that 1MEG resistor provides some RF isolation. Your circuit gets loaded less and you don't get spooky readings because of RF finding its way into the meter.

author: vk6zgo
author_rank: Super Contributor
timestamp: November 11, 2015, 10:05:06 am
content: I had one of these:-http://www.aaauctions.com/auctions/catalogs/150820/150820-019.jpgI gave it away to a "Radio Museum" which had a huge quantity of old Radio & TV gear.They were going to set up a display of a typical 1930s Radio Workshop,& welcomed the old General Radio VTVM.It never happened,though.More recently,the local council have "refurbed" the place,& I'm suspicious all but a handful have gone to landfill.I may be---I hope I am,wrong!Wish I'd kept the old beast---it didn't take up that much room! Bummer!