This is an excellent idea, but is incomplete in engineering detail.
The "trap" must be tuned to the harmonic. Reactance is generated at the
fundamental frequency, which must be compensated for using an open
circuit stub (a piece of coax which is simply clipped off until the SWR
is as low as possible).
So a four-way coax split is required.
The trap is tuned at low power by shorting the outer and inner with a
pin, while watching the attenuation of the harmonic an a receiver. Then
solder permanently. The stub is then tuned for best SWR and left open.
Unfortunately there is interaction, so the GDO will not tell the truth;
tuning is still necessary.
73,
Ian ZS6BTE
Phil Clements wrote:
>
> If you really want to get fancy, cut a piece of RG-8 coax a bit over 40 inches
> long; grid dip it and prune it to 50.100 mhz. put a suitable coax fitting on
> one end of the stub, and short the braid to the center conductor on the
> other. Install the stub with a coax "T" connector at the antenna jack of the
> amp. This gives you a "big time" connection to DC ground, and puts your
> second harmonic down about 30 db. You can do the same thing on the
> inside of the amp if you wish; just use small teflon coax for the stub, solder
> it in, and coil it up.
>
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