PMP450+CLIP vs PMP450b - Field Experiences


1) PMP 450m

2) 4656' approximately

3) 6°-7°

AP and SM is running 15.1.2

sm is at 4127' and alignment has been checked again this morning with help from earbud tone. distance from ap is 1.2 miles, ap eirp is  36dbm.

450 sm with clip yielded a receive power of -63, 450b receive power is -68 to -69.

I have done several tests between 450+clip and 450b to other sites and see a -3 to -7 difference on receive power.

Hope that gives you a little more information.     


Have sent some data in already, however is there any more updates on this? I am hesitent to continue to install these whilst the issue is unresolved.

Hardware or software?


We are seeing similar results with the 450b. With the new software patch and correct alignment we are seeing from 4 - 6db of a drop. We are also talking short distances from 1 to 3 miles. The 450b from what we see perform similar to a 450 without a clip. We are connecting these to existing access points that are tilted and directed to suit the existing customers.

We also will not purchase anymore 450b SMs until the issue is addressed.  We need the extra gain that is advertized.

We are still working on this. We have as yet been unable to reproduce these results.  If anyone is willing to send in a unit to us, we will ship a replacement to you.  Please email me directly:

matt @


I sent you an email about shipping back one of our 450b SMs

Also have reached out and sent an email.

I would like to ask anyone that believes their 450b is not performing to expectations to do the following.  This will tell us if we're chasing the right issue here.

  • Once 450b SM is registered, run 2-3 link tests from 450b SM GUI. To run link test go to : Tools >> Link Status and click Run Link Test

Figure 1 Example of Good Radio with healthy link.

  • Look at the Received Power levels for both V and H paths in Downlink as well as Uplink. (Highlighted lines in above screenshot).
  • If difference in received power levels between V pole and H pole shows delta greater than 12 dB, it can be a sign of bad hardware.

Example of Bad Radio with imbalanced Link:

If you see this condition, please open a ticket with support, and we will keep you up to date with a remedy as soon as possible.

I would also like to ask again if anyone following this thread has had good experiences with 450b.  Is it performing as expected? 

We recived an SM tested by cambium support.  After swaping our 450b out for that one our modulation impruved all the way up to 256-QAM up and down.  Our plain 450 + clip would only do 64-QAM down.

Strangely our good 450b still gets about 2-3 dBm less than our plain 450 + clip.  But the modulation is much better so I guess thats what matters.

We have tested and found a few good 450b SMs in the batch we recived.  1 out of the 5 we deployied worked as expected.  We have 70 more to test tho.  We will be contacting cambium support to return the defective units.

I love it when it's not a lemon

Hi Matt,

I have sent you an email regards recent tests.

Let me know if recieved ok.


We have received your email, and are still working this issue. Thank you.

Any further updates on this?

I'm sending back all 450b's that are unopened. Anything over 1 mile has been really poor performance on these, going to try 450D or normal 450's with clips / reflectors.

We are making progress with these issues on the initial shipments of 450b.  Stay tuned, there will be an update this week.  Sorry for the delay and problems we had with these...

Can you offer some more insight into what your going to fix with this update? Or what you believe the issue may be?


Still waiting for an update ... am I sending them back or not?

Once again, sorry for the delay.  The performance issues, aside from what is able to be tested for earlier in this thread (i.e. drastic Tx power limitations on one chain vs. the other), will be addressed by Software Release, which we are expecting to release in Beta form by Wednesday, with a target to release officially by Dec. 15th. 

If you experience the Tx power output limitations described above, this is a hardware issue that is not repairable with new software, so please open a support ticket.

The Field Service Bulletin will be issued very soon, and I will post a link to it in this thread when available. 

I just posted the FSB here.

The software is expected to be released by the end of next week (12/15).  A beta version of the software is expected earlier in the week.  I will post to this thread when it becomes available.

The good news is that we are confident we will fix nearly all of the performance issues (aside from the one described in this thread above) with this updated software.  The bad news is that we expect a few customers to run into this hardware-related issue, and they will require an RMA to replace the bad unit.

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For those following this thread, the official R15.1.2.1 software has now been released and is available on the support site in the usual spot.

Link here.

Please upgrade, and feel free to discuss results in this thread.

Hello Wisps

I see this discussion just kind of came to an end, However here we are in 2021 running 20.2.1 and using retro’s and mid/high gains with 450/450i/450m sectors and we still prefer 1st gen 450’s with the clip because they covered the middle ground that we run into a lot, Mid-gain never performed as well I know the numbers are almost identical but field experience has been less than ideal so we struggle with too little or too much RX signal to maintain 64qam or better.

We are a rural area so we have customers 1-5 miles on most sectors and the clip made most them possible without the inconvenience of a dish plus more and more we find customers don’t want a dish mounted to there home. Honestly does anyone? And as some installers know mounting a J-arm on some buildings can be difficult such as mobile homes, office work trailers or fifth wheels.

We would like to see a middle step option again while maintaining the ease of the mounting clamp of the 450,mid,retro SM’s. Maybe a retro cassegrain clip would be helpful or another option using the 450b connectorized with a comparable antenna that is not a mounting hassle that isn’t adding another $100+ to the equipment required to provide service to someone.

What are the rest of you guys using?