[1000mp] FT1000MP MK V and MFJ 1026

[Tod -ID]

Billy and others --


Billy is quite correct that running the RX OUT line into the phasing unit
[MFJ-1026, ANC-4, NCC-1, etc.] is the correct approach. The 'sense antenna'
is a separate antenna which only provides the 'line noise' signal that you
will be using to try to cancel the noise on the signal coming from the TX
antenna. 

I have looked at the schematic of the FT1000MP many times. To the best of my
ability to understand the fairly complex path taken by the RX OUT signal
from antenna input A or B to the RX OUT jack the RX OUT signal is grounded
during TRANSMIT.

On the other hand, I measured VOLTS of RF on the sense antenna when I keyed
the transmitter [1500 watts out] and that is too much for the transistors in
the MFJ-1026. That is why there is a small, 20 ma. Light bulb in series with
the AUX input to the 1026. After you burn that out you can replace it with
another one from Radio Shack or simply use the PTT signal from the FT1000MP
to key an FET relay driver that you install in the MFJ-1026 as a
modification to ground the AUX input when you transmit. 

The RX OUT goes into the MAIN input for the 1026 and the output from the
1026 [after the nulling/phasing ] goes to the RF IN jack on the back of the
FT1000MP. When adjusting ANY noise cancellation unit start with the absolute
minimum signal input on the two signal going into the unit. Increase the
antenna input signal until you can just barely hear the noise and a few
signals. The increase the signal from the sense antenna a little at a time.
Adjust the phasing and nulling controls for a maximum null. Once you have
the null settings for the controls slowly increase the antenna signal and
then add sense antenna signal and null. In the end you may have a received
signal that is 'weaker' on the S-meter than the signal directly from the
antenna and some noise may still be present, but the signal to noise ratio
should be much, much better. That will allow you to copy signals that
otherwise would not be readable.

I no longer use the MFJ-1026 but I DO use a DX Engineering NCC-1 from time
to time as a noise cancellation unit with one input of the NCC-1 connected
to the RX OUT jack and the other NCC-1 input connected to one of the DX
Engineering small verticals [108 inches high]. I used it effectively during
the ARRL SSB DX contest last weekend to null out line noise on 10-15-20-40
when my beams were pointed toward the quadrant [Europe ] that has a new line
noise source. I had an hour on 20 meters during which I worked 92 European
stations from here in Idaho. That would not have been possible without the
noise cancellation.

Since that noise was new I plan to see if I can find the source, but during
a contest weekend is not the time the power company is likely to fix a
problem unless the service is out.


There are some .wav files on my web site that show the effect of using a
noise cancellation unit with the FT1000MP.

I do recommend this approach for reducing the effect of line noise --
especially single source line noise.


Tod, K0TO



 

> -----Original Message-----
> From: 1000mp-bounces at mailman.qth.net 
> [mailto:1000mp-bounces at mailman.qth.net] On Behalf Of Billy Cox
> Sent: Monday, March 08, 2010 11:33 AM
> To: All about Yaesu 1000mp
> Subject: Re: [1000mp] FT1000MP MK V and MFJ 1026
> 
> Give consideration to using the RX IN and RX OUT jacks on the 
> back with the front panel switch set to RX ... that places 
> the 1026 in the RX line and NOT in the TX line ... so no 
> keying protection is required. So that's one option to consider.
> 
> Hope this helps!
> 
> 73 de Billy, AA4NU
>