Coil Question
 

Bob Liesenfeld wrote:

Perhaps as a audio load in the drain circuit??

Sorry.....RF load



Bob WB0POQ

You might also examine the original choke carefully and see if you can
locate the break. It's most likely to be at an end, or where the choke
has been scuffed on the outside of one of the pies. If it's at either of
these spots, you can repair it with some small wire, a steady hand, and
a good magnifier. (If it's on the outside of a pie, you'll have to
unwind a turn or two.) An X-Acto knife with a pointy blade is a good
tool for getting an outside turn loose without doing too much damage to
the turns underneath.

Roy Lewallen, W7EL

W7TI wrote:
On Fri, 4 Jul 2003 19:00:27 -0500, TH wrote:


I had an old regenerative set that was in pretty bad shape so I'm using the
parts to build a FET regen set. I just found out the old 2.5 mh choke is
open. I know I can purchase these mail order, but I'd like to get this
project completed this weekend. Looking through my boxes of old parts, I
found an old peaking coil for a tube type TV. The coil is adjustable from
.2 to 2.8 mh, at 7 ohms DC resistance. I don't see why this wouldn't work,
but thought I'd ask anyway. Will this coil be okay to use??

Thanks


__________________________________________________ ______________

Is this a coil only, or does it have a paralleled resistor? In TV jargon,
a "peaking" coil is used in the video circuits to achieve the desired
bandwidth and almost always has a built-in resistor in parallel. If yours
is just a simple adjustable coil with no resistor, should be ok.

73, Bill W7TI

You might also examine the original choke carefully and see if you can
locate the break. It's most likely to be at an end, or where the choke
has been scuffed on the outside of one of the pies. If it's at either of
these spots, you can repair it with some small wire, a steady hand, and
a good magnifier. (If it's on the outside of a pie, you'll have to
unwind a turn or two.) An X-Acto knife with a pointy blade is a good
tool for getting an outside turn loose without doing too much damage to
the turns underneath.

Roy Lewallen, W7EL

W7TI wrote:
On Fri, 4 Jul 2003 19:00:27 -0500, TH wrote:


I had an old regenerative set that was in pretty bad shape so I'm using the
parts to build a FET regen set. I just found out the old 2.5 mh choke is
open. I know I can purchase these mail order, but I'd like to get this
project completed this weekend. Looking through my boxes of old parts, I
found an old peaking coil for a tube type TV. The coil is adjustable from
.2 to 2.8 mh, at 7 ohms DC resistance. I don't see why this wouldn't work,
but thought I'd ask anyway. Will this coil be okay to use??

Thanks


__________________________________________________ ______________

Is this a coil only, or does it have a paralleled resistor? In TV jargon,
a "peaking" coil is used in the video circuits to achieve the desired
bandwidth and almost always has a built-in resistor in parallel. If yours
is just a simple adjustable coil with no resistor, should be ok.

73, Bill W7TI

It's just an adjustable coil with no resistor. Thanks for the help. The
coil is sort of bulky and I wanted to make sure it would work so I could lay
the components out on the circuit board.

This has turned out to be a great weekend project. The original radio was
hand built probably around '35 or so, but had been hacked up over the years.
I'm using the original caps, knobs, vernier, etc and to make a FET version.
It's pretty neat, the binding post for the antenna is marked "long wire ant"
and the ground lug is marked "gnd". I'm using the original coils (six each)
and the bakelite socket.

BTW, I bought the project box from Ten Tec for $6. They are having a close
out sale on discontinued enclosures.

http://www.tentec.com/enc_closeout.htm



"W7TI" wrote in message
...
On Fri, 4 Jul 2003 19:00:27 -0500, TH wrote:

I had an old regenerative set that was in pretty bad shape so I'm using
the
parts to build a FET regen set. I just found out the old 2.5 mh choke is
open. I know I can purchase these mail order, but I'd like to get this
project completed this weekend. Looking through my boxes of old parts,
I
found an old peaking coil for a tube type TV. The coil is adjustable
from
.2 to 2.8 mh, at 7 ohms DC resistance. I don't see why this wouldn't
work,
but thought I'd ask anyway. Will this coil be okay to use??

Thanks

__________________________________________________ ______________

Is this a coil only, or does it have a paralleled resistor? In TV jargon,
a "peaking" coil is used in the video circuits to achieve the desired
bandwidth and almost always has a built-in resistor in parallel. If yours
is just a simple adjustable coil with no resistor, should be ok.

73, Bill W7TI

It's just an adjustable coil with no resistor. Thanks for the help. The
coil is sort of bulky and I wanted to make sure it would work so I could lay
the components out on the circuit board.

This has turned out to be a great weekend project. The original radio was
hand built probably around '35 or so, but had been hacked up over the years.
I'm using the original caps, knobs, vernier, etc and to make a FET version.
It's pretty neat, the binding post for the antenna is marked "long wire ant"
and the ground lug is marked "gnd". I'm using the original coils (six each)
and the bakelite socket.

BTW, I bought the project box from Ten Tec for $6. They are having a close
out sale on discontinued enclosures.

http://www.tentec.com/enc_closeout.htm



"W7TI" wrote in message
...
On Fri, 4 Jul 2003 19:00:27 -0500, TH wrote:

I had an old regenerative set that was in pretty bad shape so I'm using
the
parts to build a FET regen set. I just found out the old 2.5 mh choke is
open. I know I can purchase these mail order, but I'd like to get this
project completed this weekend. Looking through my boxes of old parts,
I
found an old peaking coil for a tube type TV. The coil is adjustable
from
.2 to 2.8 mh, at 7 ohms DC resistance. I don't see why this wouldn't
work,
but thought I'd ask anyway. Will this coil be okay to use??

Thanks

__________________________________________________ ______________

Is this a coil only, or does it have a paralleled resistor? In TV jargon,
a "peaking" coil is used in the video circuits to achieve the desired
bandwidth and almost always has a built-in resistor in parallel. If yours
is just a simple adjustable coil with no resistor, should be ok.

73, Bill W7TI

On Fri, 4 Jul 2003 19:59:45 -0700, W7TI wrote:


Is this a coil only, or does it have a paralleled resistor? In TV jargon,
a "peaking" coil is used in the video circuits to achieve the desired
bandwidth and almost always has a built-in resistor in parallel. If yours
is just a simple adjustable coil with no resistor, should be ok.

Why the parallel resistor? Is it to lower Q and increase the
bandwidth?

On Fri, 4 Jul 2003 19:59:45 -0700, W7TI wrote:


Is this a coil only, or does it have a paralleled resistor? In TV jargon,
a "peaking" coil is used in the video circuits to achieve the desired
bandwidth and almost always has a built-in resistor in parallel. If yours
is just a simple adjustable coil with no resistor, should be ok.

Why the parallel resistor? Is it to lower Q and increase the
bandwidth?

On Sat, 05 Jul 2003 12:18:11 -0700, Paul Burridge wrote:

Why the parallel resistor? Is it to lower Q and increase the
bandwidth?


__________________________________________________ _______

Yes. In TV's, peaking coils are used to achieve the needed ~4.5 MHz
bandwidth in the video amplifier circuit.

--
Bill, W7TI

On Sat, 05 Jul 2003 12:18:11 -0700, Paul Burridge wrote:

Why the parallel resistor? Is it to lower Q and increase the
bandwidth?


__________________________________________________ _______

Yes. In TV's, peaking coils are used to achieve the needed ~4.5 MHz
bandwidth in the video amplifier circuit.

--
Bill, W7TI