A word about using transverters with any HF rig. Unless the rig
specifically provides a "transverter output" one needs to take certain
precautions to prevent problems and at the same time produce good results.
I have found that operating the nominal 100 watt HF rig in the 20 to 30 watt
power range provides good linearity and good IMD values with the SSB signal
and good S/n values with the transmit signal. Now that power level is much
too high to feed most if not all transverters. Therefore, a resistive pad
or attenuator should be used between the HF rig output and the transverter
input. These are easy to build starting with a 25 to 50 watt 50 ohm dummy
load for the input R, a 1/2 watt series resistor and a 1/2 watt 50 ohm shunt
resistor to ground at the output of the pad that feeds the transverter.
This forms a simple Pi pad. The value of the series resistor will depend on
the amount of attenuation and subsequent drive required by the transverter.
The drawback to the above approach requires that the HF rig have an AUX RX
input and the transverter have a separate IF output to feed the AUX RX
input. Most transverters can be easily modified to accommodate this
requirement.
Once all of this is in place, then spikes generated from the HF rig are not
a point of concern and should one forget to turn the power back, likely no
damage to the TX input of the transverter will happen. Also, I strongly
suggest that "hard keying" of the transverter be implemented as opposed to
RF sensed switching.
I have 3 high end transverters and have managed to keep all of them alive
and healthy using Tentec Paragon's, Omni VI Plus, and now the Omni VII.
73
Bob, K4TAX
----- Original Message -----
From: "Steve Berg" <wa9jml@tbc.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Thursday, January 15, 2009 6:02 PM
Subject: Re: [TenTec] 1208 Transverter
>
> I used one of these transverters with my Argonaut II, and managed to
> work all continents with it barefoot into a 4 element beam during the
> last F2 cycle. I found that it worked extremely well, and is now
> helping a friend of mine enjoy 6 meters. It gave me a whole lot less
> trouble than my so-called "higher end" transverter does. They are
> touchy about overdrive as I found out when I tried to use it with my
> Omni V.9, which apparently has a strong RF spike when keyed, but it sure
> works well with a decent QRP rig like an Argonaut. I don't see how you
> can beat one for the price.
>
> Steve WA9JML EN51
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|