The first two feed grids that have a higher impedance than a diode that
is fed by the third.

--
73
Hank WD5JFR
"Theo" wrote in message
...
In an old-style valve (tube) communications receiver circuit which
utilises two I.F. stages and uses three I.F. transformers, can someone
explain why the last I.F. transformer (which feeds the diode detector
stage) need to differ in some way to the other two?
Any help would be greatly appreciated.

Theo

"Henry Kolesnik" wrote in message
...
The first two feed grids that have a higher impedance than a diode that is
fed by the third.

Thanks Hank,
Does this mean that the windings of this third I.F. transformer need to be
different in some way than the previous two, and if so, by how much?

Theo

Theo
The secondary of the IF xfmrm feeding the diode will have a different
winding than the first two. My transformer theory is not up to snuff,
I'm 68 and if I recall correctly a diode has a much lower input
impedance that has to be matched so I'm guessing it will have less
turns. Remember that a transformer reflects the impedance back.
You may want to get a copy of The Radiotron Designers Handbook by
Langford, it covers just about anything you would want to know about
tube radios, over 1000 pages.

--
Thanks & 73
Hank WD5JFR
"Theo" wrote in message
...

"Henry Kolesnik" wrote in message
...
The first two feed grids that have a higher impedance than a diode
that is fed by the third.

Thanks Hank,
Does this mean that the windings of this third I.F. transformer need
to be different in some way than the previous two, and if so, by how
much?

Theo

Henry Kolesnik wrote:
The secondary of the IF xfmrm feeding the diode will have a different
winding than the first two. My transformer theory is not up to snuff,
I'm 68 and if I recall correctly a diode has a much lower input
impedance that has to be matched so I'm guessing it will have less
turns. Remember that a transformer reflects the impedance back.
You may want to get a copy of The Radiotron Designers Handbook by
Langford, it covers just about anything you would want to know about
tube radios, over 1000 pages.

The over 1000-page one is the Fourth Edition, which is the most expensive
on the used market, and the one which has the most hi-fi information in
it.

The discussion of IF strip design is also in the smaller and much less
expensive Third Edition. Some people like the third edition because it
has some information on transformer design which was not carried into
the fourth.

A copy of the fourth edition is available online he
http://geek.scorpiorising.ca/RDH4.html
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message
...
Henry Kolesnik wrote:
The secondary of the IF xfmrm feeding the diode will have a different
winding than the first two. My transformer theory is not up to snuff,
I'm 68 and if I recall correctly a diode has a much lower input
impedance that has to be matched so I'm guessing it will have less
turns. Remember that a transformer reflects the impedance back.
You may want to get a copy of The Radiotron Designers Handbook by
Langford, it covers just about anything you would want to know about
tube radios, over 1000 pages.

The over 1000-page one is the Fourth Edition, which is the most expensive
on the used market, and the one which has the most hi-fi information in
it.

The discussion of IF strip design is also in the smaller and much less
expensive Third Edition. Some people like the third edition because it
has some information on transformer design which was not carried into
the fourth.

A copy of the fourth edition is available online he
http://geek.scorpiorising.ca/RDH4.html
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

It would certainly help to see the schematic before jumping to conclusions.
There are many designs out there between American 5 and FT1000D, and you
don't specify.

Hey JB
I assumed since the query was in this group it wouldn't be a FT-1000 and
not an AA5 because it has only one IF. It would be nice to know what
radio but anxious people making queries and get carried away and I'm
one..
Hank
"JB" wrote in message
...
"Scott Dorsey" wrote in message
...
Henry Kolesnik wrote:
The secondary of the IF xfmrm feeding the diode will have a
different
winding than the first two. My transformer theory is not up to
snuff,
I'm 68 and if I recall correctly a diode has a much lower input
impedance that has to be matched so I'm guessing it will have less
turns. Remember that a transformer reflects the impedance back.
You may want to get a copy of The Radiotron Designers Handbook by
Langford, it covers just about anything you would want to know about
tube radios, over 1000 pages.

The over 1000-page one is the Fourth Edition, which is the most
expensive
on the used market, and the one which has the most hi-fi information
in
it.

The discussion of IF strip design is also in the smaller and much
less
expensive Third Edition. Some people like the third edition because
it
has some information on transformer design which was not carried into
the fourth.

A copy of the fourth edition is available online he
http://geek.scorpiorising.ca/RDH4.html
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

It would certainly help to see the schematic before jumping to
conclusions.
There are many designs out there between American 5 and FT1000D, and
you
don't specify.

Hey JB
I assumed since the query was in this group it wouldn't be a FT-1000 and
not an AA5 because it has only one IF. It would be nice to know what
radio but anxious people making queries and get carried away and I'm
one..
Hank

I hear ya! Most of these discussions leave the tracks in a hurry and wind
up out in the cornfield.

We don't know if a bfo or product detector or regen or filters or a
converter stage involved. Everybody else seems to have thrown the book at
him.

Over the years I've gone thru several 4th editions but have never seen
any of its predecessors. I'll have to watchout for some.

"Scott Dorsey" wrote in message
...
Henry Kolesnik wrote:
The secondary of the IF xfmrm feeding the diode will have a different
winding than the first two. My transformer theory is not up to snuff,
I'm 68 and if I recall correctly a diode has a much lower input
impedance that has to be matched so I'm guessing it will have less
turns. Remember that a transformer reflects the impedance back.
You may want to get a copy of The Radiotron Designers Handbook by
Langford, it covers just about anything you would want to know about
tube radios, over 1000 pages.

The over 1000-page one is the Fourth Edition, which is the most
expensive
on the used market, and the one which has the most hi-fi information
in
it.

The discussion of IF strip design is also in the smaller and much less
expensive Third Edition. Some people like the third edition because
it
has some information on transformer design which was not carried into
the fourth.

A copy of the fourth edition is available online he
http://geek.scorpiorising.ca/RDH4.html
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Henry Kolesnik wrote:
Over the years I've gone thru several 4th editions but have never seen
any of its predecessors. I'll have to watchout for some.

I see the second and third editions at hamfests a lot. They are often
black and less than half the width of the 4th edition so you might not
see it unless you're looking for it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Scott Dorsey" wrote in message
...
Henry Kolesnik wrote:
Over the years I've gone thru several 4th editions but
have never seen
any of its predecessors. I'll have to watchout for some.

I see the second and third editions at hamfests a lot.
They are often
black and less than half the width of the 4th edition so
you might not
see it unless you're looking for it.
--scott

I suspect people with the 4th edition just never sell
them. What I would love to find one day is the original
Australian edition of the 4th. The American (RCA) edition
was produced by photo-offset and some of the charts leave
something to be desired.


--
Richard Knoppow
Los Angeles
WB6KBL