[TenTec] Orion XVTR RF output

[Dr. Gerald N. Johnson]

On Tue, 2007-05-22 at 09:35 -0700, Rick Williams wrote:
> Thanks for the reply Martin.  I'm running 2.060b firmware.
> 
> I am using an SSB model LT6S six metre transverter.  The transverter has a
> built in adjustable attenuator and the input required is adjustable from 1
> mW to 500 mW.  I have adjusted the transverter attenuator so that 20 watts
> output (maximum spec of the transverter) is delivered when the Orion PWR
> setting is at 100.  According to the Orion manual, the power setting adjusts
> the XVTR RF output to between +5dBm and +15 dBm (about 3 mW to 30 mW).
> 
> The power settings are not the issue for me.  The issue is adjusting the MIC
> gain to obtain adequate ALC indication.  There is no problem in CW.  (I
> successfully worked Hawaii on CW yesterday so I know it's working!)
> 
> I've also received a reply (off the reflector) from a user encountering the
> "problem" I have described while operating a Down East Microwave
> transverter.
> 
> I guess the issue here is shouldn't the ALC setting be independent of
> whether a transverter is attached to the XVTR RF output connector?  Or am I
> way off base here?
> 
> 73,
> 
> Rick
> VE7TK
> 
Primarily ALC is to protect the internal PA, to limit the drive so the
intermod is acceptable. A secondary effect is to correct the analog
transmitter gain for variations from band to band that ordinarily are
present. When using the low level output that ALC detector isn't in the
circuit and there isn't the power that's present for normal antenna
connections to develop a useful ALC voltage, though its sure that a
special ALC detector could be created to have sufficient voltage. There
probably is a external ALC input for connecting to the PA. There could
be an ALC detector at the input or the output of the transverter
connected there. Just take a bit of work to customize it for the
transverter.

Transverters for VHF in G3SEK's book, "The VHF/UHF DX Book," do include
an input ALC and variable attenuator for transverter protection. There's
no reason that detected output couldn't control the exciter with ALC
input instead and no fundamental reason ALC couldn't be created by a
directional coupler at the antenna side of the transverter and that way
it could protect the transverter stages from over drive too.
-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer