Re: Coil Question

[Bob Liesenfeld]

Bob Liesenfeld wrote:

> Perhaps as a audio load in the drain circuit??

Sorry.....RF load

>
>
> Bob WB0POQ

[Roy Lewallen]

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

[Roy Lewallen]

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

[TH]

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

[TH]

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

[Paul Burridge]

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?

[Paul Burridge]

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?

[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

[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