Thread: IF Transformers
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Old October 10th 10, 01:41 AM posted to rec.radio.amateur.homebrew
Dave M[_3_] Dave M[_3_] is offline
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First recorded activity by RadioBanter: Mar 2010
Posts: 30
Default IF Transformers

Hairy Lethal wrote:
http://www.sm0vpo.com/blocks/if-txfmr_tube_00.htm
and
http://www.sm0vpo.com/begin/cans-0.htm

/Harry

"raypsi" wrote in message
...
On Aug 25, 1:12 pm, Howard James wrote:
Hey OT:

I seen one web site, wound if coils on 1/2inch PVC, turns were 65
turns for the grid and 150 turns for the plate they used a ferrite rod
or antenna rod for a tuning slug. put the coils in a tin can for like
soup;

Another site they used 2, 1mh coils in close proximity and tuning with
trim caps, all put in a cast aluminum box.

Both those idea's bigger than the old 3/4in sq can of old.

Trying to find treaded slugs could be a chore even it you wanted to
dup the old cans,

Trouble with the surplus stuff you don't know if it is 455 or 10.7
unless you test it or take it apart.

73 OT:

de n8zu




I'm about to embark on a "vintage" valve (tube) receiver but have a
question (probably more questions later!!!) about the IF
transformers. Years ago I was able to purchase the transformers for
455 KHz but the ones I want are for 9 MHz. I think I'll have to wind
them. I don't have any 10.7 MHz transformers. Any advice
appreciated. I'm really interested in the turns ratios as I'll be
winding the primaries for a Q of about 100.
Do the inter-IF amp windings have the same turns ratio as the
balanced modulator detector transformer? I think not. Do I have to
worry about turns ratio for anode impedance to grid impedance and
what are "rule of thumb" ratios? Can I use FTxx toroids as opposed
to say quarter inch coil formers with screening cans? So many
questions. It's great being a radio amateur!
Thanks. Howard.


You can buy 10.7 IF cans from Dan's Small Parts web site at
http://www.danssmallpartsandkits.net/. They're listed about 1/5 of the way
down the page. Be patient when you scroll... it's a big page and he doesn't
have a search utility on the site. Cheap enough at $1.65 each.
They're built specifically for solid state receivers, so they might not have
the right turns ratio for tube circuits. You could buy a couple and
experiment.

An alternative source for 10.7 Mhz IF transformers would be in a scrapped FM
radio. You might find a suitable donor quite cheaply at a flea market,
garage sale, etc.

--
David
dgminala at mediacombb dot net