Jim,
With the XV144 jumpers set for 1 mW drive, the attenuator resistors are
bypassed, and the Q6 gain stage is in-line.
The attenuator resistors (and the Q6 amplifier) are put into line (or
out of line) with the plugging of JP3, JP4, JP5 and JP6. There is no
dynamic switching - the XV144 is plugged for an input level ranging from
1 mW to a maximum of 8 watts. Once plugged for a particular input
range, the Input Attenuator pot can be adjusted for any particular input
level within that range. There is no automated switching of the
attenuators or the 28 MHz Q6 gain stage. It is all in the way the
jumpers are plugged. It does not "switch in" - the user has to
determine the drive level that is to be used and set the jumpers
accordingly.
If you are using the K3 (or K2 with the K60XV) to drive the XV144 (and
have the KXV3 option), set the TRNxx menu to provide 1 mW (maximum)
drive and set the XV144 jumpers to the 1 mW input level.
Then drive the XV144 with that 1 mW signal and adjust the Input
Attenuator pot to produce 20 watts with the full 1 mW drive. The K3
(K2) power knob will then adjust the power drive to the XV144 up to 1 mW
and will control the XV144 power output up to 20 watts.
Relay K7 has nothing to do with the setting of the power level (via the
jumpers). It always activates on transmit. If the jumpers are set to
JP3 and JP4 plugged to pins 1 and 2, the attenuator is bypassed.
Jumpers JP5 and JP6 select whether the Q6 gain stage in in-line or
bypassed. For 1 mW input, you want the attenuator to be bypassed and
the Q6 gain stage to be in-line. That means JP3 and JP4 are plugged
between pins 1 and 2 and JP5 and JP6 are plugged between pins 2 and 3.
Relays K6 and K7 control the path between transmit and receive so that
both Q6 and the attenuator resistors are bypassed during receive and
respond to the jumper settings during transmit.
73,
Don W3FPR
On 7/25/2014 8:15 PM, Jim Brown wrote:
On 7/25/2014 4:28 PM, Don Wilhelm wrote:
Jim,
I am looking at the XV transverter Owner's manual Rev F1 and cannot
understand your statement about the ACC cable. See Figure 7 on page
11. It clearly shows 4 wires to the ACC connector, and one of them
(pin 1 of the XV144 DB-9 connector and pin 12 of the K3 ACC end) is
the return path.
Yes, I just discovered the error -- it's my printer, that didn't
reproduce two color
conductors.
I am also concerned about your statement about the "right" level
drive to the XV144. In the XV144 there is no provision to switch in
any fixed attenuation.
It's on the control board in the form of relay K7 and three 160 ohm
resistors.
Are you certain you are looking at the XV Transverter Owner's manual
and *not* the K144XV internal option for the K3.
I'm looking at an XV144, manual dated 2013.
As for frequency stability of the XV144, without the crystal oven,
the XV144 is usually stable enough for CW and SSB operation. If
greater frequency stability is desired, the addition of the crystal
oven is desirable. Plug the JP-9 header to pins 4 and 5 to provide
power to the LO and xtal oven at all times that +12 volts is supplied
to the XV144 for the greatest LO stability.
Yes, I'm aware of the option for an oven. In a quick conversation
while he was rushing to make the flight to CT, K6XX alerted me to the
stability issue, and said to choose drive levels to avoid dissipation
in that attenuator. So I'm trying to get a handle on roughly where it
switches in. He also suggested running XV at the minimum level needed
to drive an external amp, which also makes sense.
After studying alignment instructions, I'm seeing a K3 output level of
1 mW, so perhaps that's it.
Thanks and 73, Jim
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