•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe™

Sitemap

Anode inductor - why? - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


Charl
Post subject: Anode inductor - why? Posted: Wed Jul 12, 2006 9:36 am

Colonel


Joined: Fri May 19, 2006 5:01 am
Posts: 25
Location: Netherlands
Hello folks,

I am still working on my digital tube radio, and came across this setup in the schematic of a Sherwood 3000 radio:



Both tubes are limiter stages. The IF is 10.7MHz. I estimated the value of the inductor based on size and core.

What does the anode inductor do? The thing that really puzzles me is that it is tunable (I have the radio sitting next to me). There is a turnable ferrite slug in there. What could it possibly be tuned WITH?

Thanks,
Charl


Top

nubbage
Post subject: anode inductor - whyPosted: Thu Jul 13, 2006 6:13 am

General


Joined: Fri Feb 17, 2006 12:07 pm
Posts: 218
Location: London UK
Hi Charl
It is to resonate roughly at 10.7MHz with the combination of stray capacitance around the tube base plus the anode to suppressor capacitance of the EF89 first stage plus the input capacitance of the following stage. Note the latter will be magnified somewhat by Miller Effect

Since many of these values can only be approximately estimated, the inductor is usually adjustable







Custom Search
More than 10,000 searchable pages indexed.

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger... single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website