Lamb wrote:
>
> Hi Carl:
>
> Interesting thought. Probably should not discuss receivers on the Amps
> Reflector - but it is simply the continuation of an amp related topic.
>
> It makes sense to put the rf choke at the output side of the relay so that
> it shorts anything that is not supposed to be there to ground - and, as Hans
> has suggested, improve receiving back-ground noise. There is one minor
> caution, though, in that the rf choke will drop in impedance at some point
> and affect received signals. A 2.5 mh choke would be fine through 160
> meters when using a low impedance antenna - but suppose you also use the
> receiver to receive on the broadcast band or lower - where the antenna might
> be high impedance. Thus, it might not be appropriate to hang a normal rf
> choke across the receiver input of a general coverage receiver.
>
> Sorry to digress, but it really has to do with design of power amplifiers -
> and whether the rf choke should be hung on the output side of the relay.
> There is merit to the suggestion.
>
> 73, Colin K7FM
>
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Hi Colin:
In the TL-922 amplifier the rf choke is placed on the input side of the
changeover relay. A gas discharge tube is connected between the
amplifier RF output and the input side of the relay. This approach will
discharge any voltage build up on the transmitting antenna large enough
to fire the discharge tube through the RF choke. If the receiver is used
on the lower frequencies i.e. the broadcast band, the it will not be
effected by the RF choke in the amplifier. 73.
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