Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Jan Fri 21, 2022 1:48 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 9 posts ] 
Author Message
 Post subject: Allied knight crystal radio
PostPosted: Jan Fri 14, 2022 8:10 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4044
Location: Boston, Massachusetts
I am assuming I can remove the tap, and use a slider to tune the coil.

Image

_________________
Andrew


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Fri 14, 2022 10:14 pm 
Member

Joined: Jan Sat 25, 2020 5:23 am
Posts: 867
Location: Colorado Springs, CO 80917
If you're referring to the secondary tap between the 30 & 80 turns, that's not really a tuning tap, it's to better match the crystal load to the tuned circuit (the tapped coil & variable cap).


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Fri 14, 2022 10:28 pm 
Member

Joined: May Tue 30, 2006 4:46 pm
Posts: 11097
Location: Santa Rosa, CA
I agree about the impedance matching comment. Knight probably designed around a "sweet spot." If you want to use a slider, you will have to remove insulation from the coil wires. Careful not to short adjacent turns.

Years ago I built a double slider; one side tunes the frequency, the other side tunes for best match to the detector. In practice, they both interact and I never liked the slider results. A loose coupler is better.

Attachment:
1021SliderCoil_72.jpg
1021SliderCoil_72.jpg [ 169.87 KiB | Viewed 205 times ]


Rich


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Fri 14, 2022 11:27 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4044
Location: Boston, Massachusetts
looking to build this one, not sure how to connect the variable capacitor.

https://www.youtube.com/watch?v=_XI8OWIqShk

_________________
Andrew


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Sat 15, 2022 1:23 am 
Member

Joined: Jan Sat 25, 2020 5:23 am
Posts: 867
Location: Colorado Springs, CO 80917
Hard to say what they did exactly, from looking at the poor images in the video. They might have tapped the coil but more likely if's a simple continuous coil with slider & the var capacitor across the 'active' turns selected by the slider.


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Sat 15, 2022 3:26 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4044
Location: Boston, Massachusetts
Image

_________________
Andrew


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Sat 15, 2022 6:39 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 39924
Location: SoCal, 91387
mrx wrote:
I am assuming I can remove the tap, and use a slider to tune the coil.

Image

You can tune a radio by either adjusting the inductance or capacitance (or sometimes both).

In the case of this circuit, the coil tap should remain fixed, as it's apparently located at the best spot for reception, and the variable capacitor used for tuning stations.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Sat 15, 2022 5:00 pm 
Member
User avatar

Joined: Jul Fri 18, 2008 10:02 am
Posts: 2301
Location: near ST Louis Mo 62002
Do you have the allied crystal radio or going to make one from scratch . If your going to make one use a matching transfomer and a benny and the tap on the coil is not necessary and will give you better sensitivity and selectivity . The benny and matching transfomer can be used on any crystal radio .

You may want to contact ARF member krystallo he lives near you ad he is big into crystal radios

_________________
Mark
(Conti the brain damaged robot )
PG-18-23909


Top
 Profile  
 
 Post subject: Re: Allied knight crystal radio
PostPosted: Jan Sat 15, 2022 10:40 pm 
Member

Joined: Jan Sat 25, 2020 5:23 am
Posts: 867
Location: Colorado Springs, CO 80917
mrx,

I see you are pursuing this crystal radio build in more that one thread. I think the rule here is that discussions of a device or the like are supposed to be consolidated into one thread. It gets better & clearer help for you if the people trying to help can see all of the questions & changes you are considering.


Top
 Profile  
 
Post New Topic Post Reply  [ 9 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests



Search for:
Jump to:  






































Privacy Policy :: Powered by phpBB