[Icom] Question about Icom IC-706MK2G SWR Meter

[George, W5YR]

I suspect you are right again, as usual, Adam.

I once read in interesting piece concerning the size of toroid baluns
making the point that when you try to make the cores too small, you
run into all sorts of unexpected consequences. Same evidently holds
true with a miniature current transformer made for a very small rig:
low output voltage unless larger than customary power levels are used
for SWR measurements. Guess it was an engineering tradeoff between
core size, windings, and cost of diodes.

73/72, George
Amateur Radio W5YR -  the Yellow Rose of Texas
In the 57th year and it just keeps getting better!
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
K2 #489      Icom IC-765 #2349     Icom IC-756 PRO  #2121



----- Original Message -----
From: "Adam Farson" <farson@shaw.ca>
To: <icom@mailman.qth.net>
Sent: Friday, November 29, 2002 1:47 PM
Subject: RE: [Icom] Question about Icom IC-706MK2G SWR Meter


> Hi George,
>
> From a look at the LPF board layout (Fig. 8-5, p. 11, IC-706MkIIG
service
> manual) the reflectometer transformerL33 is quite small, suggesting
few
> secondary turns. To ensure that the resulting low RF output voltage
is well
> above the offset voltage of the detector diodes, a reasonable RF
power
> throughput is required. This is probably the rationale for the 30W
minimum
> stated in the user manual.
>
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ