[AMRadio] AM Bandwidth and Audio Quality (wasSourceBroadcastXmtrs)

Wed Jun 22 00:50:44 EDT 2011

The Delta d'Arsonval meter types are completely passive, no batteries
needed.

Indeed, one could wind a large toroid core with a few turns and send the
result to a rectifier & DC meter for indication.

It will operate differently from a thermocouple-fed meter in terms of
linearity, as you won't have a crowd of indications down close to zero.

Freq response could be dictated by the ferrite series.  Delta will supply
them for HF calibration as well.

73DG

On Tue, Jun 21, 2011 at 8:54 PM, lee <pulsarxp at embarqmail.com> wrote:

> Hi Rob,
>
> Yes, this is exactly what I thought they would be.  I still think one could
> fairly easily make one.  The remote device is just a current sensor.  The
> remote unit would be an amplified meter which would be calibrated.  For $15
> you got a real bargain.  You could not make one for that price.
>
> I have an RCA BTA-1R2 I am trying to restore.
>
> Lee, w0vt
> Houston, TX
>
> -----Original Message-----
> From: Rob Atkinson
> Sent: Tuesday, June 21, 2011 10:31 PM
> To: Discussion of AM Radio in the Amateur Service
> Subject: Re: [AMRadio] AM Bandwidth and Audio Quality
> (wasSourceBroadcastXmtrs)
>
> Hi Lee, I've seen the toroid units go for $250 used.   For those who
> don't understand, we're talking about a power measurement system for
> medium wave broadcasting made by a company called Delta Electronics.
> As I understand it, the idea is to place the measuring units out at
> the tower antenna tuning units where the copper pipe to the tower from
> the ATU can pass through the center of the toroid.  This is inside a
> wx proof aluminum box that is sealed and has a N jack mounted on it.
> the hole the rf carrying pipe to the tower goes though is about 2
> inches diameter with a tough white plastic cover lining the hole and
> toroid inside.  This generates a voltage at the N jack that can be
> read via coax cable and you have one of these at each tower in a
> directional antenna so you can see the power delivered to each load.
>
> I got lucky and picked up three of the small toroid units for 1 KW
> stations from a local AM on 1580 that went dark to allow another
> property on 1590 to go to 5 KW.   I had no idea what they were at
> first but they seemed to be something that might be useful so I got
> them for $15, gave two away and kept one.   I do not have the fancy
> meter unit however.
>
> here's what one looks like:  http://www.mwpersons.com/delta.html
>
> I was mistaken--they work up to 5 mhz but with less accuracy.
>
> 73
>
> Rob
> K5UJ
>
> On Tue, Jun 21, 2011 at 8:39 PM, lee <pulsarxp at embarqmail.com> wrote:
> > Bill,
> >
> > What do these Delta units retail for?
> >
> > I bet you could build a pretty nice one for ham use with little trouble.
> > Just calibrate the meter with an accurate wattmeter into a 50 ohm dummy
> > load
> > using ohms law.  Good enough for ham use.
> >
> > Lee, w0vt
> >
> > -----Original Message-----
> > From: BILL GUYGER
> > Sent: Tuesday, June 21, 2011 8:32 PM
> > To: Discussion of AM Radio in the Amateur Service
> > Subject: Re: [AMRadio] AM Bandwidth and Audio Quality (was
> > SourceBroadcastXmtrs)
> >
> > Delta is REAL proud of their equipment so I doubt there are going to be
> > many
> > spares laying around. I just replaced 4 20 Amp. max Toroid + meter combos
> > at
> > KTCK with ones rated for 40 A. The old ones will be kept for spares for
> > KLIF
> > or
> > sent to other stations within the company that might need a replacement.
> > Not
> > saying "it ain't gonna happen" just don't hold your breath.
> >
> >
> > In addition, Delta generally only guarantees them up to 2 Mc.  They'll
> > probably
> > be fiarly accurate thru 80 M. but ????
> >
> > Bill AD5OL
> >
> >
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