DX Engineering NCC-1

[Dominic1967]

I was wondering if anyone here had experience with the NCC-1 antenna phase controller. I bought one used off eBay and in all of my troubleshooting, I'm fairly convinced it's defective. I'd like to know for sure before I submit a return request that it's not just user error, but I'll be darned if the phase knob does anything.

When using the controller as directed, I can discern absolutely no change in signal visually (waterfall) or by ear when using two active loops, about 20 feet apart. I don't suffer from any local RFI after painstakingly eliminating all offending devices, I'm more interested in nulling out QRM or QRN to dig out weaker stations.

In my troubleshooting, I have found no issues in the signal path of either antenna input A or B. I can manually change the balance between the two and attenuate each one. But when it comes to phase, I get no response. Anybody else fight with one of these before?

Thanks,
Dominic

 

[MDScanFan]

What frequencies or signals are you trying null? Are your loops the same design or are they different? Are you loops orientated in the same direction?

I use my NCC-1 with two active 3' loop antennas spaced around 30' apart to null local RFI. One of the challenges with getting an effective null is to balance the amplitude between the antennas. In my case the antennas have different gains (different designs) so I have to fiddle with the amplitude balance before I use the phase balance to null. If they are not balanced then the null is not effective. I can effectively null local interference from MW up to around 14 MHz. My setup does not have the optimal spacing but I have some success nulling MW broadcasts.

 

[Dominic1967]

What frequencies or signals are you trying null? Are your loops the same design or are they different? Are you loops orientated in the same direction?

I use my NCC-1 with two active 3' loop antennas spaced around 30' apart to null local RFI. One of the challenges with getting an effective null is to balance the amplitude between the antennas. In my case the antennas have different gains (different designs) so I have to fiddle with the amplitude balance before I use the phase balance to null. If they are not balanced then the null is not effective. I can effectively null local interference from MW up to around 14 MHz. My setup does not have the optimal spacing but I have some success nulling MW broadcasts.

Thanks for the reply. My loops are both the 3' variety- a W6LVP and an MFJ-1886. They share the same vertical polarization and I have tried them facing the same direction and perpindicular to each other.
I have no trouble attenuating the stronger one and using the balance knob to get their signals to match- I know that seems to be key but in all of my tests, regardless of frequency, I can notice absolutely no change in signal or SNR when rotating the phase knob. Not even a light dip- which is what leads me to believe I have a defective unit.
I have tried every Ham and most broadcast bands. I've tested with WWV at 10MHz, with a signal strength of S9+10.

ChatGPT, for whatever that's worth, is telling me, after it (he, she?) had me run through a bunch of tests, that the problem likely lies in

• A failed op-amp in the phase path
• A bad RC component (e.g., open cap or fried resistor)
• A broken trace or via on the board

 

[MDScanFan]

It seems like you have performed the right troubleshooting steps.

Do you have a device that causes RFI (such as a light bulb, TV, etc.)? If so, then you could try to run a nulling test against that.

Do you have any test equipment that could be used to inject signals into the inputs and observe the output?

 

[Dominic1967]

It seems like you have performed the right troubleshooting steps.

Do you have a device that causes RFI (such as a light bulb, TV, etc.)? If so, then you could try to run a nulling test against that.

Do you have any test equipment that could be used to inject signals into the inputs and observe the output?

I could certainly introduce some RFI- I might not have thrown away ALL the noisy switching AC adapters. And yes, I do have the proper test equipment. We have a pretty full Mothers Day planned for tomorrow but perhaps tomorrow night. If those tests prove I have a bad unit, I'll file an INAD with the seller. I won't waste my time trying to repair it if I can easily return it.

 

[Dominic1967]

Just to update- DX Engineering got back to me and said, based on the tests I had run, that it sounded as if the phase bridges were bad. It's possible the previous owner transmitted through the controller. Their cost for repair is 79 dollars an hour plus parts. The seller refunded my money and told me to keep it. So, now I decide whether to get it fixed or just give up on it.

 

[MDScanFan]

Did they provide a ballpark cost for the suspected issue?

 

[Dominic1967]

Did they provide a ballpark cost for the suspected issue?

No, only the $79/hour and parts. I've got nothing in it now, and even if it were three hundred bucks, it would totally be worth having a working unit, fresh from a factory repair. I'm hoping they'd let me know beforehand what the total would be. I'm just not sure what I want to do yet.

 

[a29zuk]

I have the NCC-2. I would recommend that you should get it fixed. I just use two end fed antennas and it is a great tool for eliminating noise.
It also works great on broadcast band to steer your antennas toward a station you want to listen to.

Jim

 

[pjxii]

No, only the $79/hour and parts. I've got nothing in it now, and even if it were three hundred bucks, it would totally be worth having a working unit, fresh from a factory repair. I'm hoping they'd let me know beforehand what the total would be. I'm just not sure what I want to do yet.

Just wondering about a follow up. Did you ever send it off? I have an NCC-1 which I bought used several years ago (haven't been able to use it yet) so this topic piqued my interest.

 

[dlwtrunked]

I was wondering if anyone here had experience with the NCC-1 antenna phase controller. I bought one used off eBay and in all of my troubleshooting, I'm fairly convinced it's defective. I'd like to know for sure before I submit a return request that it's not just user error, but I'll be darned if the phase knob does anything.

When using the controller as directed, I can discern absolutely no change in signal visually (waterfall) or by ear when using two active loops, about 20 feet apart. I don't suffer from any local RFI after painstakingly eliminating all offending devices, I'm more interested in nulling out QRM or QRN to dig out weaker stations.

In my troubleshooting, I have found no issues in the signal path of either antenna input A or B. I can manually change the balance between the two and attenuate each one. But when it comes to phase, I get no response. Anybody else fight with one of these before?

Thanks,
Dominic

View attachment 183347

I would first try it with just wire (non-loop) antennas if you have not. Using loops introduces other factors may make adjustments more difficult.