VK Logger Ham Radio Forum Archive

I would be interested in anybody's opinion of the MFJ 1025 noise filter. Reviews on EHAM are mostly positive. Moving from my semi-rural QTH to the noise-murky city is a bit of a shock. If there is technology that will help I will grab it.

73

Wayne VK4WDM

Hi Wayne,
Looking at the specs, this unit is only for verticals and does not go beyond 30 mhz. Good if you have 2 verticals then you have a steerable array. As for this band . Zilch.
my 2c
Brian 4QB

Hi Brian

Some of the reviewers on EHAM are using it for dipoles and loops and reporting good results.

"For a noise antenna I made a 50' end fed OCF "dipole" (often called a "No Counterpoise Antenna") from twin lead and placed it in my attic on the offending neighbors side. This antenna hears the plasma TV's in the neighborhood quite well. With this setup I am now able to COMPLETELY remove any and all plasma interference from anywhere in the neighborhood." KD6FAB

"I took an old G5RV out of mothballs and stuck it up for a noise antenna." N4HNH.

73 Wayne VK4WDM

VK4WDM wrote:I would be interested in anybody's opinion of the MFJ 1025 noise filter. Reviews on EHAM are mostly positive. Moving from my semi-rural QTH to the noise-murky city is a bit of a shock. If there is technology that will help I will grab it.

73

Wayne VK4WDM

I had a JPS ANC-4 in use for over 10 years in 2 high noise locations. I believe they are similar in design? It was very effective from 3.5mhz up to 6M on a beam, vertical and a range of different wire antennas.
You DO need to play with the noise antenna and it DOES take a fair bit of fiddling initially - you need to be very patient.
I no longer work HF so I sold it some time back.
Paul vk4apn Cairns

The ANC-4 is now being produced by Timewave and is in their current catalog. It might be a better option than the MFJ since it covers 6m.

73

Wayne VK4WDM

http://www.youtube.com/watch?v=DpftxVd-jZ8

There's a video i made showing off my 1025.. Noise antenna is as important as primary antenna.

Wow, that's quite impressive.

I've been looking at a MFJ1025 for a while now, my QTH suffers from S7-8 noise on 40m and S5-6 on 80m and 20m

Killing the power to my QTH doesn't help so the source is probably out of my control, I know they'd be lots of signals swaped by the noise that I'd love to get too!

I tried an ANC4 with my plasma tv and was able to reduce the interference on 40m from 20db over 9 to about S7, basically nulled.

Be aware that it is only really good for single point sourse noise.
it will have no real effect on "general noise"

also you will lose about 3db of signal when you use the noise filter.

the mfj has a "gain" control on the main antenna input so it can look like the noise has reduced but infact the total input signal has reduced as well.

i found that the ANC-4 seemed to perform much better for me as i have tried both here at my qth.

also tried and compared both anc4 and mfj at vk3jma's qth on the weekend, the anc4 seemed to reduce the noise issue by about 1-2 spoints better on 20m and 40m.

used both the internal antenna, external wire 2m long and and external antenna (hf vertical) as the sense antenna, all with similar results

I know its not really practical, but to get the best results here i had a full size 40m loop for my TX antenna, and another (slightly) smaller loop within the loop with about a 1.5m spacing around the whole thing.. .. if that makes sense.. a square within a square.

My noise is general noise coming from everywhere and not a single source.. The Flex3000 showed visually the impact of on/off of the MFJ.

The internal antennas on the MFJ's are only good if the noise is coming in your shack via powerlines or if the noise is generated by yourself.

Cant comment on the 1026 as i dont believe there's any circuitry difference except for a preamp.. Not needed if you use it correctly.

They are worth playing with anyway, i was ready to pack up my gear and sell it all until i tried this unit.

One thing you will need to do however is mod the 1025 and 1026. By default they are quite stupid. Ie when you transmit on one antenna, the rf comes in and smashes your station via the rx antenna.. So to solve this, i got a relay and mounted it in the unit so that on transmit, the RX antenna is grounded. Problem solved. WIthout doing this you'll keep blowing the internal 'lamps' which is the fuse.

Hi,

I have 1025 and the truth is that not if it works, because I have a problem with it:

When I connect 1025 to the position ON, the main antenna "disappears", does not hear anything, is as if it did not exist, only I can hear something with the auxiliar antenna.

If it is in OFF I hear with normality and with noise.

I have tried to change the main antenna, putting it like to auxiliar and to auxiliar like main. In this case and in position ONI hear with the connected one in the Auxiliary peg, the connected one in main deaf this one.

Really not what to do. Help

Thanks in advance

Jose

Has anyone had success with these units to alleviate the crud from inverter air conditioners?

I have a multi-head unit here i.e. single outside unit feeding 4 blowers inside, and have thus far had little succes reducing the noise. I'm aware of the info on the minikits site, and tried EMI filters on the mains feed to the outside unit, and each feed from it to the blowers but no improvement. Using a cro the main source of the crud is the PS PCB and cable feed to the motor. Filling the cable with clip on ferrites and even enclosing it in braid and earthing both ends, and a separate earth from the unit to an earth stake bonded to the copper underground water pipe has only managed to reduce the noise from S9+40 to S9+10.

Damien VK3RX