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How to Reduce CS-series Power?

AA7US
 

Does anyone know if there's a safe way to REDUCE the transmit power of a CS-series transceiver using the existing circuitry?  Would simply reducing the IRF510's bias current do the trick or would that harm the IRF510?


I ask because I'm interested in exploring the use of an external 10W RF amplifier for 20M.  It has a limit on the input power it can accept.


Thanks,


John

AA7US

Adam Rong
 

John,

It is not a good idea to reduce power by reducing IRF510's bias because it will make it work in poor situation.

How much power can you get so far? If you can get 5 watt or more, adding a power amplifier of 10 watt seems not very justified. If you really need higher power, you can consider raising the power supply voltage a little bit to somewhere at 14 volt.

Thanks,
Adam

在 2017年8月1日,上午12:30,landrjoh@... [CHINA_QRP] <CHINA_QRP@...> 写道:

 

Does anyone know if there's a safe way to REDUCE the transmit power of a CS-series transceiver using the existing circuitry?  Would simply reducing the IRF510's bias current do the trick or would that harm the IRF510?


I ask because I'm interested in exploring the use of an external 10W RF amplifier for 20M.  It has a limit on the input power it can accept.


Thanks,


John

AA7US

AA7US
 

Thank you for the reply Adam.

I don't have a CS-series transceiver working on 20M (or higher) yet.  I'm still building.

Now I do already have a 10W amplifier for 40M, 30M, and 20M which I use with very low power CW rigs and thought it might be nice to be able use it with the CS-20 and a SLA battery (~12.5 vDC).  The 10W amplifier is limited to 1W input power as built.

I think I'll just build myself a step attenuator box similar to this one:


Problem solved!

73,

John
AA7US

---In CHINA_QRP@..., <rongxh@...> wrote :

It is not a good idea to reduce power by reducing IRF510's bias because it will make it work in poor situation.

How much power can you get so far? If you can get 5 watt or more, adding a power amplifier of 10 watt seems not very justified. If you really need higher power, you can consider raising the power supply voltage a little bit to somewhere at 14 volt.

Thanks,
Adam