Re: [VHFcontesting] DEMI 1296 transverter drive power

[WBR WF4R <wbr@verizon.net>]

Bill Burgess wrote:

> I have an earlier level DEMI 1296 transverter, serial # 105 without any information on it.  I want to drive it with either a Kenwood 700A or Yaesu 480R, each being approx. 10 watts output and neither having a low power setting for ssb/cw.  I need to know the safe drive level for this unit.  Also, for those better than I in db calculations, will a 15 db attenuator in the drive transmit line be sufficient, or do I need more?
>
> 73,
>
> Bill
>
> Email: ve3cru@rac.ca
>         
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>  
Bill,
I believe that you may be referring to the xvtr designed by KK7B (Rick 
Campbell). 
You can find the info in the ARRL publication "The ARRL UHF/Microvave 
Projects Manual" Volume 1
I also have one of these.  The Block diagram on page 3-31 shows 144 MHz 
Tx IN of 0dBm, which is one
milliWatt.   A 15 dB attenuator will only attenuate 10 Watts down to 
about  300 milliWatts.  20 dB attenuation
will take 10 Watts down to 100 milliwatts;  30 dB attenuation from 10 
Watts will still give you 10 milliWatts of
drive.   So it looks like you'll need about 40 dB of attenuation to take 
ten Watts down to 1 milliWatt.

Hope this helps.  73, Bill, WF4R

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