Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Jul Fri 20, 2018 9:05 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 4 posts ] 
Author Message
 Post subject: Determining 1st and 2nd IF transforners
PostPosted: May Tue 22, 2018 3:07 am 
Member

Joined: Nov Sun 22, 2009 9:21 am
Posts: 186
Location: UK
I'm assembling a hacked together Am receiver, I have some IF transformers from an unknown 50's set.
How can I tell which is 1st and 2nd IF.
I'm thinking 1st has a wider passband than the 2nd, and this probably means there will be a larger difference in inductance of the pri and sec windings.
Does this sound about right?, if so a simple check with an inductometer is all thats needed.


Top
 Profile  
 
 Post subject: Re: Determining 1st and 2nd IF transforners
PostPosted: May Wed 23, 2018 4:13 am 
Member

Joined: Apr Thu 12, 2007 3:24 am
Posts: 1448
Location: Milwaukee,WI
Its also possible to adjust the bandwidth by the spacing of the primary and secondary. So each side may measure the same in both trans.


Top
 Profile  
 
 Post subject: Re: Determining 1st and 2nd IF transforners
PostPosted: May Wed 23, 2018 4:48 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2176
Location: Saskatoon
If you can safely pull the shield off them, the 1st IF should have primary and secondary about the same size. The 2nd IF often has a smaller secondary. If the 2nd IF has the same size primary and secondary, then there's a good chance that you could use either one in either position.

Measuring inductance will likely give confusing results unless you temporarily disconnect the internal capacitors before measuring.


Top
 Profile  
 
 Post subject: Re: Determining 1st and 2nd IF transforners
PostPosted: Jun Tue 19, 2018 12:07 am 
Member

Joined: Jun Fri 19, 2009 6:34 pm
Posts: 7747
Location: Long Island
2nd IF transformers sometimes have lower impedance secondaries to allow for driving diode detectors which present more of a load. You may be able to determine this by testing at resonance with a signal generator, scope, and a load resistor; if there's any difference (and in some cases there wasn't), the 2nd IF will appear to have a lower output voltage than the 1st for the same primary voltage and the same load. Coil inductance alone won't tell you about the coupling to the primary.

_________________
"Hell, there are no rules here--we're trying to accomplish something!"

Thomas A. Edison


Top
 Profile  
 
Post New Topic Post Reply  [ 4 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 4 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB