PTP820C Installation - Again Struggling with Link Issues for Dual Polarization


Recently we changed an existing PTP820S 11GHz installation to an 820C installation re-using existing 2 foot dishes from the 820S 11Ghz install for dual polorization mode and put in the required circular transition and OMT Kit. Previously with the 820S we were getting a signal around 36-38dBm and was a good link. No alignment issues. The distance is close to 5km - so not a very great distance. Dishes were the same required as per link planner.

On changing to the 820C we could only get 57-60dBm. We then tried re-alignment - still not better than 57-60dBm. We can never seem to get better than this signal. Link planner is telling us we should expect around 36dBm or so. Our adaptive rate is also not where it should be for this link. I have attached some info. Has anyone seen this issue before? We did do a double check of the radio serial numbers (as as last issue with the PTP820S links I posted previously) and they look ok. So I'm really scratching my head on this one. Anybody with ideas, greatly appreciated.

We have taken one end of the link off to double check transition and OMT and looks ok (photos attached). The other end is a bit more difficult to get to - but will look at this shortly.

Unit Serial Nos - C110082B055A, C110082B056A

Running Version 9.7

Frequencies as per screenshots. Link planner details in screenshot.

Any ideas or suggestions we can try to see about getting this link up to proper capacity or what we should be checking?

Hello, this post has some useful information for troubleshooting initial link turn up: 

and alignment:

It appears that your frequencies and part numbers are valid: 

C110082B055A   PTP 820C Radio 11WGHz,TR500,Ch7W13,Hi,11425-11725MHz

C110082B056A   PTP 820C Radio 11WGHz,TR500,Ch7W13,Lo,10915-11207MHz

Have you double-checked that they are installed on the correct sides and the Hi frequencies are configured on the Hi radio (and vise versa).

Also, in addition to the OMT kit, have you changed out the single polarity antenna interface to the circular adapter?  This is referenced as the 'twist' in the installation guide.

Can you provide the LINKPlanner project file and screenshots of: the individual radio configuration pages, MRMC configuration (under symmetrical scripts>FCC)?  If desired, you can email them to 

Hi Chris,

Pretty sure it is not alignmenet as it is exactly the same dish and mounting that the 820S was on and we were getting alot better signal with that. (We just changed out the radio unit and adapters)

We did put in the circular adapter (didnt see in the photos). We will double check this on the other link end (however both of the other rectangle adapters are in the office ..)

The following frequencies are set -

C110082B056A - Radio Slot 2 Port 1 - TX 10995 ; RX 11485  ; Port 2 - TX - 11075 RX - 11565 - TX Level 23 for both

C110082B055A - Radio Slot 2 Port 1 - TX 11485 RX- 10995 ; RX ; Port 2 - TX - 11565 RX - 11075 ; - TX Level 23 for both

Script parameters are -

Parameters for script: 1501, ETSI+FCC Operational mode: Adaptive Maximum profile: 9, 1024 QAM, 635.551 Mbps Minimum profile: 0, 4 QAM, 114.326 Mbps Adaptive power: Disable

I have also emailed the link planner report for you.

Not too sure on the issues .... any help appreciated to work out what it may be. Pretty sure we have something wrong somewhere ... not sure where ...

Have you raised a support ticket? The 20dB lower RSL leads me to believe this is a physical layer issue. Did you use the correct manufacturer specific OMT interface? If it's a Radiowaves dish it needs a Radiowaves OMT interface, etc. And are the radios on both ends level? If one is a few degrees off this can result in signal degradation. Is the OMT kit in the right frequency range?


Yes - working with Chris Fikert and have sent photos of the installation, config files, link planner and screenshots.

Have also sent parts list and confirmed parts are correct and frequencies are set correctly.

Both dishes level and aligned  - was already working install of a PTP820S and swapped out to 820C.

We are going back to again check all issus- agree it must be something physical - radios have had loopback test done ok - but struggling to find that issue.

If V-pole of site A is pointing to H-Pole of Site B, you would have 20dB lower at least. I don't know how can that happen if you already confirm that your installation is proper.