[Boatanchors] "Clamp-On Ammeter" question

[Phil]

Hi All,

In the past, if I needed to measure the current draw of a device, I 
removed the fuse (if it had one) and put one of my DVMs, set to measure 
current across the fuseholder.  IF no fuse then I jury-rigged a test setup.

Today I bought one of those whiz-bang clamp-on ammeters that Harbor 
'Fright' sells  (the 'big' one, $13.59 after the 20% coupon).  Yeah, I 
know, they're not lab grade, but should be better than nothing.  I also 
realize that with the "transformer coupling" the clamp-on feature is 
only for AC.

I intend to modify my DBT (Dim Bulb tester) to use as an interface 
between the Isolated Variac and the DUT by installing a small DVM (one 
of the "freebie" Harbor Fright meters) in the DBT and a switchable "loop 
of wire" for the clamp-on in parallel with the light socket.  This way I 
can simultaneously monitor both the Voltage and current draw of the DUT.

The clamp-on meter I bought has three ranges, 20, 200 & 1000 Amps, all a 
bit high for testing the primary current draw of the typical radio item.

Here comes the question:  In old age the brain cells regarding the most 
basic radio theory I learned as a child seem to have self erased.  In 
transformer coupling, I 'think'  it's one for one. That is, IF I put a 
coupling loop of two turns in the primary lead of the DUT and clamp the 
meter over that double loop, the sensitivity of the meter would double.  
That is, instead of a 20Amp range, it would then be a 10 amp range.  4 
Turns would change a 20 Amp range into a 5 Amp range.

DO I HAVE THINGS RIGHT, or do I have it backwards??  Inquiring minds 
want to know. . .


-- 
73 From "The Beaconeer's Lair"
Phil, KO6BB
http://www.qsl.net/ko6bb/  (Web Page)

HF/LF RADIOS:
Grundigs: S-350 (~2006), G6 (2011) & S450DLX (2014).
HOMEBREW: 7 Tube+Rect 1v3 Regenerative RX for LF (built 2015)
Icom:     IC-735 Transceiver (~1990).
Icom:     R-75, Cascaded 250/125Hz CW-Filt, Panadapter. (~2009)
Icom:     IC-7200 Transceiver (~2015).
R-Shack:  DX-380 digital portable (~1990).
SDR:      Softrock Ensemble II LF (built from a kit 2015).
Zenith:   Royal-7000 Transoceanic Portable (~1968).

ACC:   HOMEBREW  LF-MF Pre-Amp, MFJ-993B HF Auto-Tuner.
        HOMEBREW  4 Port Multicoupler, Feeds Antenna to 4 RX's.
        HOMEBREW  8 Hz Audio Filter.
        Timewave  DSP-599zx Audio Filter.
        Behringer 1202fx Audio Mixer (for mixing/routing audio).

ANTENNAS: 88 foot Long Ladder-line fed dipole, 35 feet AGL for MW/SW.
           Active Mini-Whip, 36 Feet AGL for LF/MW/SW.
           37 foot "Low Noise Vertical", 11 feet AGL for LF/MW/SW.

Merced, Central California, 37, 18, 37N   120, 30, 6W CM97rh