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I've purchased the 50-watt amplifier kit, to be built for 80m, and bought assembled the 40m and 20m amps from Ray, VA7SK (very nice solder job, btw); on 40m it certainly makes a noticeable difference of 6dB -10dB on reports and it's much easier to reach Europe.

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Question: Can I leave the amplifier inline between the QDX and the antenna if the amplifier is off?? I'm not seeing that addressed in the assembly manual nor could I find an answer by searching the messages here.? I think so based on the schematic, but I don't trust my circuit reading skills enough to risk the QDX or the amplifier.??

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Thanks,

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Jim

K8DDV

Without DC power you have no bias? for the diode switching so its high

loss for RX and tx.

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Allison
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Allison,

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How about if I keep the amplifier on but remove the PTT cable.? The amp is on now, but not transmitting, and it's drawing 0.00 Amps.??

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Jim

K8DDV

Jim, are you talking transmitting through it, or just receiving?

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Nate

N8BTR

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Hi Nate.

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Transmitting and receiving.? I'd like to put a switch on the PTT going to the amplifier so that if I want the amplifier in the circuit, all I do is flip the PTT switch so that the amplifier will see 5V when the QDX transmits.

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I don't mind keeping the amplifier on all the time as the current used is nil.

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Jim

K8DDV

Hi Jim,

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I do not believe the PIN diodes have enough bias (reverse and forward) to allow the external transmitter to work.? It should be easy to install a relay that bypasses the amp altogether.

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73

Evan

AC9TU

The attenuator is after the TX diode switch.? Not a factor.

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However the RX switch does not have enough bias current to

transmit thought it.

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Still at, you cannot, even when powered and no ptt.

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Assuming your using BNC cables its only a barrel coonnector

to bypass the amp.

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--

Allison
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