RX2 Isolation Question:
I noticed this radio does NOT have much isolation from ANT1 AND RX2 antenna ports.
I have physical switches on both my Main Antenna and my Receive Only Antenna, both plugged into the appropriate ports on the radio.
When I switch OFF my main antenna and have my receive antenna on, the MAIN receiver window picks up about 20 db noise compared to if I then switch OFF my RX antenna.
Is this normal for this radio? Comparing it to my FTDX101 - there is complete isolation.
Internal Noise?
Note the pictures. I could not take a screen shot as I had everything unplugged except the bare minimum to run the anan. I have ruled OUT power supply and ran on battery - and the picture is with both antennas unplugged.
Is this normal?
RX2 Isolation and Internal Noise Question
RX2 Isolation and Internal Noise Question
- Attachments
-
- IMG_1611.jpeg (2.93 MiB) Viewed 1485 times
-
- IMG_1612.jpeg (3.25 MiB) Viewed 1485 times
Re: RX2 Isolation and Internal Noise Question
I've never measured it, but it is probably fair to say there is not a lot of isolation in the RF section of the Apache hardware.
However, any noise you are seeing probably isn't from internal to the RF hardware, not that it doesn't generate a few birdies here or there.
First, you need to put a dummy load or termination on all unused ports. If you are looking for internal noise that means all ports. I bought a bunch of cheap 50 ohm terminators off of Amazon.
Second, you need to get the PC and display as far from the RF hardware as you can in order to rule out noise from those sources. Make a 50ft or 100ft LAN cable. However, in any case it's unlikely a keyboard or mouse is contributing, so you can add those back in in order to get legit screen shots. Another alternative that might be OK is to use something like Teamviewer, VNC or RDP to run the PC in a headless mode. That will eliminate any monitor/keyboard/mouse induced effects, and you can still get screenshots.
Third, be sure that your grounding and bonding is top notch.
On my ANAN-8000 here's what 30M looks like to me when I switch ANT1 to the dummy load. My PC is far from the radio rack, not that there isn't plenty of technology in the rack itself. All unused ports are terminated. There is a ton of grounding/bonding. See my qrz.com page for station info.
The noise floor line is showing -145dBm.
Interestingly, those little stripes on the waterfall on the FT8 sub-band are indeed FT8 signals being received on the ANT3 port. They were about -80dBm peak and were showing up at about -130dBm. So there's about 50dBm of isolation between ANT1 and ANT3 ports in this case, which isn't too bad. I've never bothered to measure ANT1 to RX2 isolation.
However, any noise you are seeing probably isn't from internal to the RF hardware, not that it doesn't generate a few birdies here or there.
First, you need to put a dummy load or termination on all unused ports. If you are looking for internal noise that means all ports. I bought a bunch of cheap 50 ohm terminators off of Amazon.
Second, you need to get the PC and display as far from the RF hardware as you can in order to rule out noise from those sources. Make a 50ft or 100ft LAN cable. However, in any case it's unlikely a keyboard or mouse is contributing, so you can add those back in in order to get legit screen shots. Another alternative that might be OK is to use something like Teamviewer, VNC or RDP to run the PC in a headless mode. That will eliminate any monitor/keyboard/mouse induced effects, and you can still get screenshots.
Third, be sure that your grounding and bonding is top notch.
On my ANAN-8000 here's what 30M looks like to me when I switch ANT1 to the dummy load. My PC is far from the radio rack, not that there isn't plenty of technology in the rack itself. All unused ports are terminated. There is a ton of grounding/bonding. See my qrz.com page for station info.
The noise floor line is showing -145dBm.
- Capture.JPG (669.11 KiB) Viewed 1450 times
Interestingly, those little stripes on the waterfall on the FT8 sub-band are indeed FT8 signals being received on the ANT3 port. They were about -80dBm peak and were showing up at about -130dBm. So there's about 50dBm of isolation between ANT1 and ANT3 ports in this case, which isn't too bad. I've never bothered to measure ANT1 to RX2 isolation.
Re: RX2 Isolation and Internal Noise Question
Thank you for the detail reply.
I did some more digging and found Diversity was enabled which based on the past setting was attentuating the main receiver. When I would flip my receive antenna on it would normalize the signal. Thus why I perceived an increase in noise. My mistake.
Regarding the spurs and other noise - a few of us on Facebook had a dialogue and another produced almost a near identical screen shot as I posed. Hash with a long peak. Others have come back and verbally stated similar. Just wondering if this noisy fan is the culprit.
I did some more digging and found Diversity was enabled which based on the past setting was attentuating the main receiver. When I would flip my receive antenna on it would normalize the signal. Thus why I perceived an increase in noise. My mistake.
Regarding the spurs and other noise - a few of us on Facebook had a dialogue and another produced almost a near identical screen shot as I posed. Hash with a long peak. Others have come back and verbally stated similar. Just wondering if this noisy fan is the culprit.
Re: RX2 Isolation and Internal Noise Question
But have you terminated all the input connectors? Until you do that you can't blame the rig for internal noise.
Return to “Everything Else: Antennas, Relays, Switches, Power, Grounding, Cooling, etc.”