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Title: MB-40 DL Grid Tning Network Post by: W4AAB on January 31, 2013, 07:46:16 PM What is the difference between a National MB-40 DL and a MB-40SL? I have a 40DL and can't find any info on it.
Joe W4AAB Title: Re: MB-40 DL Grid Tning Network Post by: Steve W8TOW on January 31, 2013, 07:54:08 PM The SL version is "swinging link"...
73 Steve w8tow Title: Re: MB-40 DL Grid Tning Network Post by: W4AAB on January 31, 2013, 07:58:10 PM The DL has a swinging link of sorts. I will see if I can get a picture to you later.
Joe W4AAB Title: Re: MB-40 DL Grid Tning Network Post by: w1vtp on February 02, 2013, 01:41:51 PM I have the SL and the DL. The SL one has been hammy hamboned and will be looking to restore that one to original condition. I think the other one is a DL but post it here for you guys comments. Upon close scrutiny, the relationship to the two coils have been changed also. Any comments? I have also uploaded the info paper on the MB40SL
Al Title: Re: MB-40 DL Grid Tning Network Post by: W4AAB on February 02, 2013, 02:30:04 PM I sold the DL to a friend of mine. I had the info from AMWindow.otg and the MB40-SL app notes. Could you post a closeup of the -DL only? Thanks!!
Joe W4AAB Title: Re: MB-40 DL Grid Tning Network Post by: w1vtp on February 02, 2013, 08:46:01 PM I sold the DL to a friend of mine. I had the info from AMWindow.otg and the MB40-SL app notes. Could you post a closeup of the -DL only? Thanks!! Joe W4AAB Is that what this is? I thought it was a bastardized -SL Al Title: Re: MB-40 DL Grid Tning Network Post by: Opcom on February 02, 2013, 11:55:49 PM The hambonery there with the extra wire turns around the small coil is to smooth out the efficiency and 'frequency response', make it easier to drive. There is an article on that, saying the higher frequencies were made easier to drive.. I'd see if it matches and if so test it, it could be just the thing.
I collected all the MB-like articles I could find, and have that, but not on this computer. It's a new desktop and the data spindles have not been moved over yet. BTW 8 cores and 4 FPUs at 4GHz, 32GB ram, and a solid state system drive, wow. wait for nothing. Anyway, it's a one-pager from QST, probably mentioned in another MB-xx topic; Title: Re: MB-40 DL Grid Tning Network Post by: Steve - K4HX on February 03, 2013, 11:26:42 AM Manual here.
http://www.amwindow.org/tech/pdf/mb40sl.pdf Title: Re: MB-40 DL Grid Tning Network Post by: w1vtp on February 03, 2013, 01:05:25 PM Manual here. http://www.amwindow.org/tech/pdf/mb40sl.pdf Unless I missed something somewhere in the article, pretty much the same content that I put up on an earlier post in this thread. Let me know if I missed something. I can remove my file as this is a better copy. Still looking for that article that tells about that hammybonized coupling between the link and the coil set on the front of the unit. Help would be appreciated. I suppose I could try it anyway. BTW, anyone got that link assembly on an otherwise wrecked MB40SL? Al Title: Re: MB-40 DL Grid Tning Network Post by: Opcom on February 17, 2013, 03:21:54 AM See QST 1956 February, page 45. There is another one regarding the added coil, but i can't find it right now.
Title: Re: MB-40 DL Grid Tning Network Post by: w1vtp on February 17, 2013, 10:49:20 AM See QST 1956 February, page 45. There is another one regarding the added coil, but i can't find it right now. Thanks! I downloaded the page from ARRL's archive section. Solves some efficiency problems that result in overheating in some cases Al |