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THE AM BULLETIN BOARD => Technical Forum => Topic started by: kc2we on June 18, 2020, 10:14:57 AM



Title: Another MB-40 tech question
Post by: kc2we on June 18, 2020, 10:14:57 AM
I am looking for a scan of an advertising page by National Radio.
QST Dec 1950, page 77. A description of the National MB-40L Tank Circuit.

Since itís an advertisement itís not found during a search on the existing library of documents since itís not actually an article.
Sine ARRL staff is working from home, there's no way to get this from the ARRL until further notice. If you have this QST and can scan one page, that wud be great. Tnx in advance. kc2we@arrl.net


Title: Re: Another MB-40 tech question
Post by: WD5JKO on June 18, 2020, 11:58:34 AM

I'm not sure if you have these, but I attach two files.

Jim
Wd5JKO


Title: Re: Another MB-40 tech question
Post by: WA4WAX on June 19, 2020, 09:51:40 AM
I will scan or photograph the Nose article.

The 40 is a trouble maker in grid tank service without his mods.  One part is removing that ground strap.  He explains all in detail.

February 1956 QST.



Title: Re: Another MB-40 tech question
Post by: kc2we on June 19, 2020, 11:06:51 AM
Tnx for the heads up on the 1956 QST article. ST


Title: Re: Another MB-40 tech question
Post by: Opcom on June 21, 2020, 09:25:13 PM
If you don't get enough drive on the high band side, a small 2 turn pancake coil of #14 or 16 placed in between the two sections of the HF coil is a good place to inject your drive. will need a switch 80-20M / 15-10M

in schematic, disregard everything except the MB-40 notes about the added winding.
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands