Message-ID: <5099439E.60107@iup.uni-heidelberg.de>
Date: Tue, 06 Nov 2012 18:06:38 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: TRANSVERTERS
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Mal,

If you're generating 500 kHz with a HF TRX then this can happen. I guess 
the output transformer of the PA appears almost like a short cut for the 
output FETs, so the losses will be relatively high.
A 3 dB attenuator on the output will not help of course.
One method may be to contact the driver directly, as you say. Or, find 
the pot to allow to set the output power to even lower levels. I have an 
IC-275H for 2m which has a pot to adjust the RF power from 10...100W. 
But inside there is a seconds pot. With this pot it is possible to 
increase the range to 1...100W !

Or you may try to run the TRX on 11V instead of 13.8V! Just insert 2 or 
3 diodes in series...

73, Stefan/DK7FC

Am 06.11.2012 17:45, schrieb mal hamilton:
>    RIG/TRANSVERTER HEAT
> I have noticed when running a Transceiver at low power for Transverter 
> or other use the Transceiver PA gets very HOT so it would appear that 
> this is an inefficient approach except the Transceiver has a dedicated 
> low power output.
> I was wondering what system was used to reduce this power. It would be 
> better to disable the PA and take the output from the driver stage.
> It is vy noticeable on an IC-706
> de G3KEV

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Mal, <br>
<br>
If you're generating 500 kHz with a HF TRX then this can happen. I
guess the output transformer of the PA appears almost like a short cut
for the output FETs, so the losses will be relatively high.<br>
A 3 dB attenuator on the output will not help of course.<br>
One method may be to contact the driver directly, as you say. Or, find
the pot to allow to set the output power to even lower levels. I have
an IC-275H for 2m which has a pot to adjust the RF power from
10...100W. But inside there is a seconds pot. With this pot it is
possible to increase the range to 1...100W !<br>
<br>
Or you may try to run the TRX on 11V instead of 13.8V! Just insert 2 or
3 diodes in series...<br>
<br>
73, Stefan/DK7FC<br>
<br>
Am 06.11.2012 17:45, schrieb mal hamilton:
<blockquote cite="mid:002901cdbc3e$193684d0$0501a8c0@xphd97xgq27nyf"
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  <div><font face="Arial">&nbsp;&nbsp;&nbsp;RIG/TRANSVERTER HEAT</font></div>
  <div><font face="Arial">I have noticed when running a Transceiver at
low power for Transverter or other use the Transceiver PA gets very HOT
so it would appear that this is an inefficient approach except the
Transceiver has a dedicated low power output.</font></div>
  <div><font face="Arial">I was wondering what system was used to
reduce this power. It would be better to disable the PA and take the
output from the driver stage.</font></div>
  <div><font face="Arial">It is vy noticeable on an IC-706</font></div>
  <div>&nbsp;</div>
  <div><font face="Arial">de G3KEV</font></div>
  <div>&nbsp;</div>
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