[AMRadio] RF Ammeters (Was AM Bandwidth)

[Dennis Gilliam]

Carrier shift is pretty simple to measure:  A simple RF sample, attenuated a
bit and fed into a diode & DCMa meter.

Add a bit of C across the meter for damping and/or R in series with the
diode for swamping (adds linearity).

Cal to center scale with the transmitter on.  Modulate to taste, and if it
moves a bit more than a slight wiggle, you have CS.

73DG

On Tue, Jun 21, 2011 at 7:43 PM, W2XJ <w2xj at nyc.rr.com> wrote:

> That is one explanation but negative carrier shift can be a sagging
> power supply, weak tubes or mistuning, among other things.
>
> On 6/21/11 9:03 PM, Kim Elmore wrote:
> > I'd think that it should by indicating a current increase greater (or
> > less for negative shift) than that expected under 100% modulation. By
> > definition, an asymmetric audio source (positive peaks larger than
> > negative peaks or vice versa) is not stationary and so results in an
> > average DC offset. This would produce carrier shift, wouldn't it?
> >
> > Kim N5OP
> >
> > At 07:48 PM 6/21/2011, you wrote:
> >> Dennis,
> >>
> >> Interesting meter and I wish I could afford one.  The thing that struck
> >> me when reading the specifications was that it will show Carrier Shift.
> >>
> >> I can't help but wonder how many of us know what Carrier Shift is or how
> >> to cure it if you have it?  Is there another method to know if you have
> >> Carrier Shift?
> >>
> >>
> >>
> >> Jim/W5JO
> >>
> >>
> >> ----- Original Message -----
> >>
> >>> If one wants to use an ammeter in your transmission line for power
> >>> measurement, try getting your hands on a toroidal sampler meter such
> >>> as made
> >>> by Delta Electronics.  They are very accurate (some have an expanded
> >>> scale)
> >>> and you can get an easily repeatable reading.
> >>>
> >>> Used ones show up in the clutches of those taking engineering care of
> >>> AM BC
> >>> stations.
> >>>
> >>> 73DG
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