IF Transformers
Howard James
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.
Andreu
raypsi
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
Hairy Lethal
and
http://www.sm0vpo.com/begin/cans-0.htm
/Harry
"raypsi" <rbor...@gmail.com> wrote in message
news:bfa66b24-13ee-480f...@x42g2000yqx.googlegroups.com...
Leon
Many years ago I designed and built a 9 MHz IF amplifier using FETs
and home-made coils using toroidal cores.
Leon
Dave M
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
raypsi
> You can buy 10.7 IF cans from Dan's Small Parts web site athttp://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 n
Hey OT:
Dans small parts is a gr8 site. the reason he calls it small parts
because he got not many parts for tubes, those IF cans won't hold up
to the voltage that is on the plates of tubes, unless you might be
able to use 12volt plate voltage tubes that Tung Sol came out with
back in the day just as transistors were taking over. I remember in
1960 I had a Buick Special car, the radio that used 12 volt plate
voltage tubes and a transistor AF output.
I seen sum web site that used a 12AX7 at 12 volt plate voltage, maybe
if you used a 12AX7 in cascode you could get enough gain at 12volts
plate voltage.
The best bet I've seen is a toroid with trim caps for tuning. Way back
in the day b4 they used treaded ferrite slugs they used trim caps to
tune the IF cans.
73 OT
de n8zu