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 Post subject: Atwater Kent model 21 help needed
PostPosted: Jun Mon 17, 2019 8:26 pm 
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Joined: Mar Thu 20, 2008 4:02 pm
Posts: 2532
Location: Prescott AZ
I am trying to save a very corroded sad sack AK model 21 dry cell set.
Both wire wound RF grid bias resistors are corroded, broken and open and I need to have an idea of their value to replace them. Both AF transformers also are open but I think they are pretty standard in terms of value.

I can't find a parts list with values or a schematic with values for the AK model 21 set. I suspect some of the values are different from the model 20C which used 5V 01A tubes instead of the dry cell -99 tubes.

I would appreciate any help here.
Thanks,
Mark

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 Post subject: Re: Atwater Kent model 21 help needed
PostPosted: Jun Mon 17, 2019 9:24 pm 
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Joined: Nov Tue 14, 2017 5:09 am
Posts: 2013
Location: Austin, Texas
The resistors are listed as 600 ohms in this schematic by W3NLB.
Attachment:
AK21.jpg
AK21.jpg [ 78.12 KiB | Viewed 160 times ]


Those aren't bias resistors. They are Q spoilers to reduce tendency to oscillate.

Jay


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 Post subject: Re: Atwater Kent model 21 help needed
PostPosted: Jun Mon 17, 2019 9:51 pm 
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Location: Maryland 20709, USA
Modern schematic with parts values is here:
http://www.atwaterkent.info/TechData/Dr ... 780sch.pdf

- Leigh

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