I'm interested in building a Hiker's Two regenerative radio

[Dave.H]

I'm interested in building a Hiker's Two regenerative radio (http://
www.oldradios.co.nz/hikers/) and was wondering if an old Rola audio
transformer I pulled from a late 1960's 5 valve radio would work in
it. The transformer is marked 7000 / 15 on the top. On the side is
written "2" in a circle. It has a green wire and a black wire coming
out one side and a red wire and a blue wire out the other. If this
transformer doesn't work, I was wondering if P-T156 at www.tubesandmore.com
would work. That one has the 1:3 ratio specified in the Hiker's
schematic.

 

[Dave.H]

On May 14, 3:17 am, "Dave.H" <the19...@googlemail.com> wrote:

I'm interested in building a Hiker's Two regenerative radio (http://www.oldradios.co.nz/hikers/) and was wondering if an old Rola audio
transformer I pulled from a late 1960's 5 valve radio would work in
it. The transformer is marked 7000 / 15 on the top. On the side is
written "2" in a circle. It has a green wire and a black wire coming
out one side and a red wire and a blue wire out the other. If this
transformer doesn't work, I was wondering if P-T156 atwww.tubesandmore.com
would work. That one has the 1:3 ratio specified in the Hiker's
schematic.

Sorry about the long title, Google Groups screwed up, somehow

Dave

 

[Dave]

"Dave.H" <the1930s@googlemail.com> wrote in message
news:2a0da7cc-0c89-4f18-a13c-d19215d809f9@j33g2000pri.googlegroups.com...

I'm interested in building a Hiker's Two regenerative radio (http://
www.oldradios.co.nz/hikers/) and was wondering if an old Rola audio
transformer I pulled from a late 1960's 5 valve radio would work in
it. The transformer is marked 7000 / 15 on the top. On the side is
written "2" in a circle. It has a green wire and a black wire coming
out one side and a red wire and a blue wire out the other. If this
transformer doesn't work, I was wondering if P-T156 at
www.tubesandmore.com
would work. That one has the 1:3 ratio specified in the Hiker's
schematic.

If you need a transformer with a 1:3 ratio, then the output transformer from
a tube amp won't work. These transformers typically have primary impedances
in the range of 2000 to 10000 ohms and secondaries with 2 to 16 ohm windings
for speakers. I'd guess that yours is 7000 primary and 15 ohms secondary,
yielding a ratio of 1:466.

What WOULD work is a power transformer from a solid state amp. Generally
these run with about +/-50VDC B+, which is about 35VAC prior to
rectification. Your line voltage is about 115, so 35:115 = ~1:3.3.

Dave

 

[Dave.H]

On May 14, 8:23 am, "Dave" <dspear9...@yahoo.com> wrote:

"Dave.H" <the19...@googlemail.com> wrote in message

news:2a0da7cc-0c89-4f18-a13c-d19215d809f9@j33g2000pri.googlegroups.com...

I'm interested in building a Hiker's Two regenerative radio (http://
www.oldradios.co.nz/hikers/) and was wondering if an old Rola audio
transformer I pulled from a late 1960's 5 valve radio would work in
it. The transformer is marked 7000 / 15 on the top. On the side is
written "2" in a circle. It has a green wire and a black wire coming
out one side and a red wire and a blue wire out the other. If this
transformer doesn't work, I was wondering if P-T156 at
www.tubesandmore.com
would work. That one has the 1:3 ratio specified in the Hiker's
schematic.

If you need a transformer with a 1:3 ratio, then the output transformer from
a tube amp won't work. These transformers typically have primary impedances
in the range of 2000 to 10000 ohms and secondaries with 2 to 16 ohm windings
for speakers. I'd guess that yours is 7000 primary and 15 ohms secondary,
yielding a ratio of 1:466.

What WOULD work is a power transformer from a solid state amp. Generally
these run with about +/-50VDC B+, which is about 35VAC prior to
rectification. Your line voltage is about 115, so 35:115 = ~1:3.3.

Dave

Our line is 240 volts, 50 Hz, here in Australia.

 

[Dave]

"Dave.H" <the1930s@googlemail.com> wrote in message
news:cdb7835c-c4dd-4226-afc5-4341be4c8f32@p39g2000prm.googlegroups.com...

Our line is 240 volts, 50 Hz, here in Australia.

Dunno' how the 50Hz would affect things, probably not much in the
application you're contemplating. In North America and Europe, many if not
most power transformers in consumer-grade equipment have windings which
allow both 120 and 240VAC operation... you'd just apply 240V to a centre tap
on the primary winding vs. 120 end-to-end to get the same voltage out.
Units lacking a switch on the back to change voltage have a jumper on the
power supply PCB next to the transformer to determine your input voltage.

Dave

 

[Tim Wescott]

On Tue, 13 May 2008 10:17:55 -0700, Dave.H wrote:

I'm interested in building a Hiker's Two regenerative radio (http://
www.oldradios.co.nz/hikers/) and was wondering if an old Rola audio
transformer I pulled from a late 1960's 5 valve radio would work in it.
The transformer is marked 7000 / 15 on the top. On the side is written
"2" in a circle. It has a green wire and a black wire coming out one
side and a red wire and a blue wire out the other. If this transformer
doesn't work, I was wondering if P-T156 at www.tubesandmore.com would
work. That one has the 1:3 ratio specified in the Hiker's schematic.

You may want to ask this question on rec.radio.amateur.boatanchors and
rec.radio.amateur.homebrew. I'm tempted to cross-post my reply, but I'm
resisting it.

Transformers in all but the smallest of volume of manufactured equipment
are usually custom wound, so just going by the identifying marks doesn't
mean much. If it's an interstage transformer then chances are that it is
pretty close to what you need.

If the P-T156 transformer is an audio interstage transformer, and if the
audio impedances cited are in the 10's of kohms, then it'll probably work.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

 

[Dave.H]

On May 15, 1:47 am, Tim Wescott <t...@seemywebsite.com> wrote:

On Tue, 13 May 2008 10:17:55 -0700, Dave.H wrote:
I'm interested in building a Hiker's Two regenerative radio (http://
www.oldradios.co.nz/hikers/) and was wondering if an old Rola audio
transformer I pulled from a late 1960's 5 valve radio would work in it.
The transformer is marked 7000 / 15 on the top. On the side is written
"2" in a circle. It has a green wire and a black wire coming out one
side and a red wire and a blue wire out the other. If this transformer
doesn't work, I was wondering if P-T156 atwww.tubesandmore.comwould
work. That one has the 1:3 ratio specified in the Hiker's schematic.

You may want to ask this question on rec.radio.amateur.boatanchors and
rec.radio.amateur.homebrew. I'm tempted to cross-post my reply, but I'm
resisting it.

Transformers in all but the smallest of volume of manufactured equipment
are usually custom wound, so just going by the identifying marks doesn't
mean much. If it's an interstage transformer then chances are that it is
pretty close to what you need.

If the P-T156 transformer is an audio interstage transformer, and if the
audio impedances cited are in the 10's of kohms, then it'll probably work.

--
Tim Wescott
Control systems and communications consultinghttp://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes,http://www.wescottdesign.com/actfes/actfes.html

The P-T156 is stated as being an audio interstage transformer, with a
primary current of 10 mA, so I'll use that, instead.

Dave

 

[sparky]

On May 14, 10:12 am, "Dave" <dspear9...@yahoo.com> wrote:

"Dave.H" <the19...@googlemail.com> wrote in message

news:cdb7835c-c4dd-4226-afc5-4341be4c8f32@p39g2000prm.googlegroups.com...



Our line is 240 volts, 50 Hz, here in Australia.

Dunno' how the 50Hz would affect things, probably not much in the
application you're contemplating.  In North America and Europe, many if not
most power transformers in consumer-grade equipment have windings which
allow both 120 and 240VAC operation... you'd just apply 240V to a centre tap
on the primary winding vs. 120 end-to-end to get the same voltage out.

Usually dual voltage transformer operated equipment has two primary
windings
rated at 120 volts each. They are used in paralllel for 120 volts and
in series
for 240 volts.

Units lacking a switch on the back to change voltage have a jumper on the
power supply PCB next to the transformer to determine your input voltage.

Dave