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Old January 19th 04, 02:44 AM
VE3PMK
 
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Default Who sells high wattage non-inductive resistors?

Anyone know where to buy or how to make resistors suitable for a T2FD or
other folded HF dipole designs?

I'm currently using a 330 ohm, 2 watt carbon one, but as such it only usable
for receiving. I'd like to find an assortment of values, 100W min,
preferably 150 to 200 watts, non-inductive.

Who sells such items, or is there a way to make them?


Thanks,
Pat

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Old January 19th 04, 05:03 AM
Cecil Moore
 
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VE3PMK wrote:
Anyone know where to buy or how to make resistors suitable for a T2FD or
other folded HF dipole designs?

I'm currently using a 330 ohm, 2 watt carbon one, but as such it only usable
for receiving. I'd like to find an assortment of values, 100W min,
preferably 150 to 200 watts, non-inductive.

Who sells such items, or is there a way to make them?


I would send you an email but I don't hold out any hope for
Send me an email. I have a bunch of 600 ohm, 50 watt, non-inductive resistors.
Two in parallel gives 300 ohms at 100 watts. Four in series-parallel gives
600 ohms at 200 watts, etc.
--
73, Cecil
http://www.qsl.net/w5dxp



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Old January 19th 04, 06:00 AM
Eric Behr
 
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In article ,
VE3PMK wrote:
Anyone know where to buy or how to make resistors suitable for a T2FD or
other folded HF dipole designs?


I'm only aware of Ohmite, www.ohmite.com. Last I checked they were
out of values useable for a T2FD. I got an email from a sales rep
promising to try and get me some samples, but it's been 2 months,
so I am not hopeful anymore. Makes me wonder how those companies
survive; they advertise a sought-after one-of-a-kind product, and
then they are unable or unwilling to sell it...

--
Eric Behr | NIU Mathematical Sciences | (815) 753 6727
| http://www.math.niu.edu/~behr/ | fax: 753 1112
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Old January 19th 04, 06:22 AM
Dave Platt
 
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In article ,
Eric Behr wrote:

I'm only aware of Ohmite, www.ohmite.com. Last I checked they were
out of values useable for a T2FD. I got an email from a sales rep
promising to try and get me some samples, but it's been 2 months,
so I am not hopeful anymore. Makes me wonder how those companies
survive; they advertise a sought-after one-of-a-kind product, and
then they are unable or unwilling to sell it...


Another option is Caddock. They make some noninductive power film
resistors - the ones in TO-247 cases, well heatsinked, might be a
decent way to build up the bird-foot-warmer for a T2FD.

Mouser carries some of the Caddock resistors. I'm almost certain that
Allied and Newark do, as well.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
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Old January 19th 04, 11:28 AM
Roy Lewallen
 
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Eric Behr wrote:
In article ,
VE3PMK wrote:

Anyone know where to buy or how to make resistors suitable for a T2FD or
other folded HF dipole designs?



I'm only aware of Ohmite, www.ohmite.com. Last I checked they were
out of values useable for a T2FD. I got an email from a sales rep
promising to try and get me some samples, but it's been 2 months,
so I am not hopeful anymore. Makes me wonder how those companies
survive; they advertise a sought-after one-of-a-kind product, and
then they are unable or unwilling to sell it...


If you were a large company interested in buying 100,000 resistors,
they'd be plenty happy to sell it -- and you'd get the samples, too.

That's how they survive. For sure, they don't survive by selling onsies
to hams.

Roy Lewallen, W7EL



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Old January 19th 04, 11:54 AM
KC1DI
 
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Default

Surplus sales of Nebraska has a good selection but they are pricey.
73 Dave


On Mon, 19 Jan 2004 03:28:00 -0800, Roy Lewallen
wrote:

Eric Behr wrote:
In article ,
VE3PMK wrote:

Anyone know where to buy or how to make resistors suitable for a T2FD or
other folded HF dipole designs?



I'm only aware of Ohmite, www.ohmite.com. Last I checked they were
out of values useable for a T2FD. I got an email from a sales rep
promising to try and get me some samples, but it's been 2 months,
so I am not hopeful anymore. Makes me wonder how those companies
survive; they advertise a sought-after one-of-a-kind product, and
then they are unable or unwilling to sell it...


If you were a large company interested in buying 100,000 resistors,
they'd be plenty happy to sell it -- and you'd get the samples, too.

That's how they survive. For sure, they don't survive by selling onsies
to hams.

Roy Lewallen, W7EL


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Old January 19th 04, 02:56 PM
Eric Behr
 
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Default

In article ,
Roy Lewallen wrote:
Eric Behr wrote:

I'm only aware of Ohmite, www.ohmite.com. Last I checked they were
out of values useable for a T2FD. I got an email from a sales rep
promising to try and get me some samples, but it's been 2 months,
so I am not hopeful anymore. Makes me wonder how those companies
survive; they advertise a sought-after one-of-a-kind product, and
then they are unable or unwilling to sell it...


If you were a large company interested in buying 100,000 resistors,
they'd be plenty happy to sell it -- and you'd get the samples, too.


I would think so, but I asked about several value/power combos,
and the rep found 0 stock in all warehouses. So even if I wanted
100,000 I'd have to wait for them to make me some... Seems odd. I
normally have no problem getting "onsies" either for free or a
nominal charge from other big manufacturers, if I can't find them
in retail. Oh, well.

--
Eric Behr | NIU Mathematical Sciences | (815) 753 6727
| http://www.math.niu.edu/~behr/ | fax: 753 1112
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Old January 19th 04, 03:45 PM
Tarmo Tammaru
 
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www.mouser.com sell Caddock non inductive resistors. The 100 W are about $10
ea in onses.

Tam/WB2TT
"VE3PMK" wrote in message
...
Anyone know where to buy or how to make resistors suitable for a T2FD or
other folded HF dipole designs?

I'm currently using a 330 ohm, 2 watt carbon one, but as such it only

usable
for receiving. I'd like to find an assortment of values, 100W min,
preferably 150 to 200 watts, non-inductive.

Who sells such items, or is there a way to make them?


Thanks,
Pat



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Old January 19th 04, 06:29 PM
Art Unwin KB9MZ
 
Posts: n/a
Default

"Tarmo Tammaru" wrote in message ...
www.mouser.com sell Caddock non inductive resistors. The 100 W are about $10
ea in onses.

Tam/WB2TT
"VE3PMK" wrote in message
...
Anyone know where to buy or how to make resistors suitable for a T2FD or
other folded HF dipole designs?

I'm currently using a 330 ohm, 2 watt carbon one, but as such it only

usable
for receiving. I'd like to find an assortment of values, 100W min,
preferably 150 to 200 watts, non-inductive.

Who sells such items, or is there a way to make them?


Thanks,
Pat


What are the drawbacks to using std wire wound resistors if one
orients them in CW and CCW fashion?
Since they are in series the capacitance should be minimal
Art
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Old January 20th 04, 04:01 PM
Steve Nosko
 
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OK, nice to know, but I thought the OP was questioning using separate
resistors. OR did I miss the implication that the idea was to wind his/her
own?



Coupling two (probably wire-wound) resistors (coils) of unknown internal
physical construction seems very dubious to me. They aren't constructed to
get a specified inductive coupling. They typically will go side-by-side,
but not end-to-end very well. As you say "closely coupled" I think is the
key.



If you CAN get coupling (of two _individual_ coils-resistors) , won't it
be selective rather than broad band (the normal purpose for wanting non
inductive in the first place)? Isn't broad-band and parallel wire windings
pretty much synonymous? Like in Baluns? I'd have to see how these
non-inductive, wirewound resistors are wound. My "you can't get something
for nothing" bone says its a critical and precise construction.



I should stop here because I think I've already gone from true familiarity
to speculation - albeit interesting and supposedly educated speculation, but
speculation none the less.
--
Steve N, K,9;d, c. i My email has no u's.



"Bill Turner" wrote in message
...
On Mon, 19 Jan 2004 16:43:47 -0600, "Steve Nosko"
wrote:

a CW coil won't somehow subtract the inductance of a CCW coil.


__________________________________________________ _______

Sure it will, if the two windings are closely coupled. That's how
"non-inductive" wirewound resistors are made. I put non-inductive in
quotes because the cancellation is rarely if ever perfect and some
inductance almost certainly remains, but it is a long-used technique.

--
Bill, W6WRT



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