[TowerTalk] Dummy Load power resistors...questions!

[n0tt1 at juno.com]

I think you're right there Jim.  I see on the schematic it is named: 
"DUMMY, LOAD, MODULATOR"

Charlie, N0TT

On Mon, 29 Jun 2020 11:34:43 -0700 jimlux <jimlux at earthlink.net> writes:
> On 6/29/20 10:33 AM, n0tt1 at juno.com wrote:
> > OK, thanks Jim,
> > 
> > Interesting why Bendix would call this thing (in part) a
> > "modulator"...nothing
> > in there to modulate a RF signal that I know about....just a high 
> power
> > 50-ohm dummy load.
> > 
> 
> It's a dummy load for a modulator, so the nomenclature might have 
> been 
> arranged that way, and along the line, a comma or something got 
> dropped.
> 
> 
> that is, it might have been "Dummy Load, Modulator"
> 
> 
> 
> 
> 
> > 73,
> > Charlie, N0TT
> > 
> > On Sun, 28 Jun 2020 20:04:01 -0700 jimlux <jimlux at earthlink.net> 
> writes:
> >> On 6/28/20 7:32 PM, n0tt1 at juno.com wrote:
> >>> Thanks to Jim and Chuck!
> >>> Definately non-inductive for this application, but the power
> >> rating
> >>> is, I don't know.  I know it was used at a 5KW AM radio station
> >> for
> >>> some testing.  I should have mentioned that the glass tubes 
> look
> >>> like common florescent tubes....white in color with no hint of
> >> carbon,
> >>> etc.  I would do some more examination but I sure don't want to
> >> risk
> >>> breaking one of them.  They are now back in their case, sealed 
> by
> >> a
> >>> "jillion" screws!!!
> >>> I looked at
> >>>
> >>
> > 
>
https://theelectrostore.com/content/datasheets/kanthal_globar_resistors.p
> > df
> >>> Doesn't appear to be anything similar in appearance, but like 
> Jim
> >> said
> >>> there's
> >>> lots of area for cooling.  It could be that there's something
> >> inside the
> >>> tubes which can't been seen.
> >>> Unfortunately I threw away some electronic industrial catalogs
> >> from the
> >>> late 1960's
> >>> era.  Oh! BTW, this dummy load was made by Bendix and it's 
> called
> >> a
> >>> "Dummy Load Modulator".  Not sure what the "modulator" 
> reference
> >> means.
> >>> I do have photos if anyone wants a look.
> >>
> >>
> >> probably either an AM transmitter or radar transmitter.
> >>
> >> The modulator in a radar transmitter is the thing that generates 
> HV
> >> pulses of the correct length and voltage.
> >>
> >> The modulator in a AM transmitter is an audio amplifier that 
> puts
> >> out as
> >> much audio power as used in the RF.
> >>
> >>
> >>
> >>
> >>> 73,
> >>> Charlie, N0TT
> >>> On Sun, 28 Jun 2020 12:01:58 -0700 jimlux <jimlux at earthlink.net
> >>> <mailto:jimlux at earthlink.net>> writes:
> >>>   > On 6/28/20 11:43 AM, n0tt1 at juno.com <mailto:n0tt1 at juno.com>
> >> wrote:
> >>>   > > Hello everyone,
> >>>   > >
> >>>   > > I recently aquired a "commercial" dummy load that I'm 
> sure
> >> will
> >>>   > handle
> >>>   > > more than 2kw.
> >>>   > > There are 12, 600-Ohm resistors in parallel that measure
> >> 50-Ohms
> >>>   > with a
> >>>   > > Ohmmeter.
> >>>   > > The resistors look like frosted glass tubes with metal 
> end
> >> caps.
> >>>   > They
> >>>   > > measure 9.5" in length
> >>>   > > and 1" diameter.  The number stamped on the ends is 
> E9935R
> >> and
> >>>   > their
> >>>   > > vintage is late 60's.  A Google search for that exact 
> number
> >>>   > turned up
> >>>   > > nothing.
> >>>   > >
> >>>   > > Question:  Does anyone know the power rating of these
> >> resistors
> >>>   > and
> >>>   > > what type of resistor are they?
> >>>   >
> >>>   > They might be non-inductive power resistors from 
> Carborundum
> >> corp
> >>>   > (now
> >>>   > part of Sandvik, as I recall). I've got a bunch of them,
> >> although
> >>>   > mine
> >>>   > are grey or brown.
> >>>   >
> >>>   > They could also be a thin film resistor deposited on a 
> ceramic
> >>>   > substrate. Same idea - lots of area for cooling.
> >>>   >
> >>>   >
> >>>   >
> >>>   >
> >>>   > >
> >>>   > > I have photos.
> >>>   > >
> >>>   > > 73,
> >>>   > > Charlie, N0TT
> >>>   > >
> >>>   > > _______________________________________________
> >>>   > >
> >>>   > >
> >>>   > >
> >>>   > > _______________________________________________
> >>>   > > TowerTalk mailing list
> >>>   > > TowerTalk at contesting.com 
> <mailto:TowerTalk at contesting.com>
> >>>   > > http://lists.contesting.com/mailman/listinfo/towertalk
> >>>   > >
> >>>   >
> >>>   > _______________________________________________
> >>>   >
> >>>   >
> >>>   >
> >>>   > _______________________________________________
> >>>   > TowerTalk mailing list
> >>>   > TowerTalk at contesting.com <mailto:TowerTalk at contesting.com>
> >>>   > http://lists.contesting.com/mailman/listinfo/towertalk
> >>>   >
> >>
> >>
> > 
> 
>