[GCARC] 2:1 SWR

[Tony Starr]

While it may be true that solid state final amplifiers with fixed tuning
for a 50 ohm system have some degree of mismatch capability, keep in mind
that even a perfect antenna may not be 50 ohms resistive.  A perfect dipole
of around 70 ohms as well as a perfect ground plane vertical of around 35
ohms will start out at close to 1.5 to 1 at band center, and will only get
worse as one moves out toward the edges of the band. This is why built-in
tuners became a standard feature in solid state radios in the first place.

I agree with the presenter that the equipment manufacturers are doing us a
great dis-service by not building in enough working mismatch range into
their equipment.  They are likely doing this to cut down on size, weight,
and cost; and not just in the output devices, but with all of the ancillary
components that make up the final output stage.  Solid state transmitters,
as good as they are, still have significant room for improvement.

de K3TS

On Thu, Jun 6, 2024 at 9:46 AM Karl Frank W2KBF via GCARC <
gcarc at mailman.qth.net> wrote:

> To followup the topic of antenna matching/SWR from the meeting last night,
> I
> looked up the recommendations from ICOM and YAESU for two of my HF rigs
> that
> do NOT have an internal tuner.
>
> For the IC-7100, ICOM recommends an SWR less than 1.5:1 and says that power
> foldback will occur with an SWR greater than 2:1.
>
> For the FT-891, Yaesu recommends an SWR of less than 1.5:1 and does not
> mention power foldback.
>
> So Chris AD2CS was correct to question the statement that any SWR less than
> 2:1 is no problem.
>
>             Karl W2KBF
>
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