Q: how to characterize an I.F. "can"

M

Michael

Guest
I have a one-board, transistorized AM receiver that is inop. Two of its
three I.F. transformers were torn off and are lost. I want to get
replacements for them. Unfortunately the manufacturer of this receiver
is long out of business so replacement parts are not available.
Fortunately all three I.F. "cans" are identical - have the same part
number - according to the schematic.

While the schematic shows that these cans have a capacitor, it does not
indicate impedances or turns ratio. I'd like to know how to test the
one remaining transformer and characterize it so that I might track down
a third-party replacement. Its tuning slug is YELLOW, even though it's
the 3rd I.F.

Any ideas?

--
Michael
---
Addy is fake. Pls reply via this NewsGroup.
 
By frequency and not much else. I seem to recall IF transformers are listed
in the Digi-Key catalog.

These are 455 kHz IF transformers if it's an AM radio of conventional
design. They will of course need aligning after replacement.

There is probably also a red one for the local oscillator... right?

"Michael" <NoSpam@att.net> wrote in message
news:40B35CF8.3F076FA2@att.net...
I have a one-board, transistorized AM receiver that is inop. Two of its
three I.F. transformers were torn off and are lost. I want to get
replacements for them. Unfortunately the manufacturer of this receiver
is long out of business so replacement parts are not available.
Fortunately all three I.F. "cans" are identical - have the same part
number - according to the schematic.

While the schematic shows that these cans have a capacitor, it does not
indicate impedances or turns ratio. I'd like to know how to test the
one remaining transformer and characterize it so that I might track down
a third-party replacement. Its tuning slug is YELLOW, even though it's
the 3rd I.F.

Any ideas?

--
Michael
---
Addy is fake. Pls reply via this NewsGroup.
Click to expand...
 
"Michael A. Covington" wrote:
By frequency and not much else. I seem to recall IF transformers are listed
in the Digi-Key catalog.

These are 455 kHz IF transformers if it's an AM radio of conventional
design. They will of course need aligning after replacement.

There is probably also a red one for the local oscillator... right?

"Michael" <NoSpam@att.net> wrote in message
news:40B35CF8.3F076FA2@att.net...
I have a one-board, transistorized AM receiver that is inop. Two of its
three I.F. transformers were torn off and are lost. I want to get
replacements for them. Unfortunately the manufacturer of this receiver
is long out of business so replacement parts are not available.
Fortunately all three I.F. "cans" are identical - have the same part
number - according to the schematic.

While the schematic shows that these cans have a capacitor, it does not
indicate impedances or turns ratio. I'd like to know how to test the
one remaining transformer and characterize it so that I might track down
a third-party replacement. Its tuning slug is YELLOW, even though it's
the 3rd I.F.

Any ideas?
Click to expand...

Hello, Michael "PIC programmer" Covington! Just realized who had
answered my post.

Yes, the I.F. is 455 KHz. Guess I could have mentioned that.
There is no proper "can" in this local osc.; antenna feeds a transformer
wound on a bobbin.

I see in an old Mouser catalog that they once carried physically small
transformers similar to what I need. Ignoring the two larger beasties
and ones
without capacitor narrows the field considerably, but the possibilities
which are left have 2-3 impedances and/or turns ratios. It's looking
like this could be another trial-and-error project.

--
Michael
---
Addy is fake. Pls reply via this NewsGroup.
 
Try checking for a 25 cent transistor radio at your local
Good Will. Pull the back off to see if it has the ones you
need. These IF cans are all the same for these AM's.
Only thing different is the size.

"Michael" <NoSpam@att.net> wrote in message
news:40B39A59.4DBE7163@att.net...
"Michael A. Covington" wrote:

By frequency and not much else. I seem to recall IF transformers
are listed
in the Digi-Key catalog.

These are 455 kHz IF transformers if it's an AM radio of
conventional
design. They will of course need aligning after replacement.

There is probably also a red one for the local oscillator...
right?

"Michael" <NoSpam@att.net> wrote in message
news:40B35CF8.3F076FA2@att.net...
I have a one-board, transistorized AM receiver that is inop.
Two of its
three I.F. transformers were torn off and are lost. I want to
get
replacements for them. Unfortunately the manufacturer of this
receiver
is long out of business so replacement parts are not available.
Fortunately all three I.F. "cans" are identical - have the same
part
number - according to the schematic.

While the schematic shows that these cans have a capacitor, it
does not
indicate impedances or turns ratio. I'd like to know how to
test the
one remaining transformer and characterize it so that I might
track down
a third-party replacement. Its tuning slug is YELLOW, even
though it's
the 3rd I.F.

Any ideas?


Hello, Michael "PIC programmer" Covington! Just realized who had
answered my post.

Yes, the I.F. is 455 KHz. Guess I could have mentioned that.
There is no proper "can" in this local osc.; antenna feeds a
transformer
wound on a bobbin.

I see in an old Mouser catalog that they once carried physically
small
transformers similar to what I need. Ignoring the two larger
beasties
and ones
without capacitor narrows the field considerably, but the
possibilities
which are left have 2-3 impedances and/or turns ratios. It's
looking
like this could be another trial-and-error project.

--
Michael
---
Addy is fake. Pls reply via this NewsGroup.
Click to expand...
 
Hello, Michael "PIC programmer" Covington! Just realized who had
answered my post.
Click to expand...
Yes... I wish I could figure out a way to make money from NOPPP... it gets
thousands of hits every month! At least not many people expect me to
troubleshoot their NOPPPs any more...

Yes, the I.F. is 455 KHz. Guess I could have mentioned that.
There is no proper "can" in this local osc.; antenna feeds a transformer
wound on a bobbin.
Click to expand...
I suggest getting some discarded radios and looking for a similar
transformer. The transformer is very unlikely to be the defective component
in a broken radio.

Enjoy!


--
Clear skies,

Michael Covington -- www.covingtoninnovations.com
Author, Astrophotography for the Amateur
and (new) How to Use a Computerized Telescope
 
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