I have an IM-18 that I modified to have the same circuit as the IM-28, of of the successors to the IM-13 you have. I did the mod back in the mid-70s when I worked at the Heathkit store in Atlanta. Thanks for the info about the current on the ohms ranges.
What a great news, two new videos from Radio Mechanic, thanks! Vern, your channel is one of the most interesting and useful ones about electronics. When I've seen it for the first time, my first impression was: "this guy is definitely not an amaturer but a professional in what he does". I always had special respect to all of my teachers and to all those people who share their professional knowledge with others, - this is priceless. Thank you for your work, I hope you'll be able to do videos more regularly!
Recently picked one of these up, Seems all original kit build, Warmed it up and it calibrates fine, does have the yellow paper cap and the yellow inked black caps. (many people says replace without question today).
Everyone has a few regrets in life. Now, I have to add another... that being not finding out about your RU-vid channel earlier. I've learned, and continue to learn, significantly from you and truly appreciate you taking your valuable time to give back to your community and the younger generations. Have a blessed 2024 Vern!
Thank you I appreciate the kind words. I am presently in Thailand and haven't been making any electronics videos. Since retirement I spend my Winters in thailand. You should check out David tipton, Dave's radio adventures.
Enjoy your time in Thailand! I certainly watch as many of David's videos as I can muster and am learning much from him as well. Thank you for the referral!@@theradiomechanic9625
The number you speak of actually indicates the number of electrically independent electrodes, which includes the heater. With metal octal valves however, the metal envelope is counted also, so you have 6A7 and 6A8. This was carried over to the glass octal versions, such as 6A8G, even though there is no metal envelope to connect to. There are exceptions though; namely the 5Y3G, 6B6G and 6P7G, but there were no initial metal versions of those valves. There are exceptions to that logic too, namely 5U4G, 6U7G etc. The vast majority of valves, however, do follow the convention.
At least your brain has the more recent 286. I am still running on a Z80. By the way, I had a lot of fun playing with those old Zilog chips. And they are still very useful today.
A lot of those meters will blow filaments on Battery operated tube type Transoceanic, H503 type Zenith, RCA radios. 1L6 is the best example, being, from my experience, the most vulnerable, and most expensive. I just paid 60..00 for another NOS 1L6
Can't remember the model number but have the blue case and white panel with black lettering otherwise pretty sure insides are the same as your meter.. I like that Eico meter too. It's been awhile since I used any of my vtvms. Have a couple of digital meters and Simpson 260 that get used the most
That will be the IM-5228. I have one which I fully restored including stripping the case and having it powder coated again, then got my screenprinter to do the graphics/lettering on the front panel. Looks like it just rolled off the factory floor!
just a note that 12AT7/12AV7/12AZ7 are adequate substitutes for the 12AU7 . 12AU7s are getting expensive and 12AV7 or 12AZ7 can still be found NOS at low cost 12AX7won't work - it doesn't have enough drive (cathode current)
Antique Electronic Supply has them at various price ranges, E-bay has them but be sure you shop around because some people are asking stupid prices. Look in your area for any Ham Radio Flea markets or Antique Radio Flea markets. I see them all the time for a buck or two.
There’s nothing wrong with shot gunning the paper caps as long as you track what you’re replacing with the schematic. Developing a good technique is the key to successful restoration. Checkout the vital components before jumping in and hacking everything. Track your work along the way. Checking paper caps is , at best, a waste of time.
