1176 Lundahl Transfomers + Output Stage Modification

[djwig]

Hi folks,
now a new attempt to repost my question about the 1540s.
i measured it with a scope and found out some strange results.
look at the pdf file (i used some resistors as described on the lundahl page for asymmetric inputs). the source resistance was adjusted to 600ohms.

lundahl link:
http://www.lundahl.se/pdfs/datash/1540.pdf

my results:
http://djwig03.100free.com/upload/messungen%20trans.pdf
(maybe you have to cut paste it into a new browser window).

another thing:
there may be a improvement i want to discuss here reguarding in leaving out a transistor in the output stage (one in the darlington stage is cut out as described here:
http://djwig03.100free.com/upload/kickout_transistor_komplett.JPG ).
(maybe you have to cut paste it into a new browser window).
measuring it gave a much higher cut off frequency
any comments?

and at the end: some pictures of my work so far:

http://djwig03.100free.com/upload/IMG_0003.jpg
http://djwig03.100free.com/upload/IMG_0004.jpg
http://djwig03.100free.com/upload/IMG_0006.jpg
http://djwig03.100free.com/upload/IMG_0009.jpg
http://djwig03.100free.com/upload/IMG_0010.jpg
http://djwig03.100free.com/upload/IMG_00112.jpg
(sorry, 500k per picture)
(maybe you have to cut paste it into a new browser window).
hope it works

greetings

Jan

 

[Guest]

[quote author="djwig"]Hi folks,
now a new attempt to repost my question about the 1540s.
i measured it with a scope and found out some strange results.
Jan[/quote]


why strange results?
5402 is output transformer
1540 is input transformer.

It only means, that winding resistances are several orders diferent and
you can not compare them /in one type circuit/
5402 must be hard feed, 1540 can be soft feed. You can not
interchange it.


in 1540 you measures hi freq resonancy on 60 kHz as in datasheet.
xvlk

 

[djwig]

[quote author="xvlk"]
why strange results?
5402 is output transformer
1540 is input transformer.

It only means, that winding resistances are several orders diferent and
you can not compare them /in one type circuit/
5402 must be hard feed, 1540 can be soft feed. You can not
interchange it.


in 1540 you measures hi freq resonancy on 60 kHz as in datasheet.
xvlk
[/quote]

oh maybe i didn't express my idea right:
it is just that by measuring and comparing input and output Transformer, the cut off frequency of the 1540 is much lower as the 5402.
i was not thinking about interchange the two or use two 5402.
when measuring the 5402 i made a circuit as described on the lundahl page for the 5402: source below 15ohms, load 600ohms).

i' m just wodering why the two differ so much. thats all

 

[gyraf]

The maximum high frequency available will always be higher in low-z transformers than in high-z transformers because of leakage inductance and capacitance.

This is simply the price you pay for not loading the previous stage too hard - approximating a voltage transfer in stead of a current transfer.

The reason is the much higher number of turns needed to acheive the high primary inductances needed to transfer low frequencies generated by high source impedances.

The 1540 is >10K "bridging" impedance, and the 5402 is 600 or less.

Jakob E.