PTP820s/c powering options


Is it possible to power s or c version via PoE++ switch? If switch has enough power budget?
Which standard is used for powering 820?

Kind regards

EDIT: Why would we need this? It comes in handy in cases when we have to reboot device remotely. I know 820 is stable and normally it doesn't need rebooting manually, but just thinking if it is even possible...

Hello, this may be possible for the PTP820S, but the PTP820C probably has too much of a draw to make this work in a 2+0 configuration.  The PTP series is not technically standards based, in terms of power, but I have heard of instances where POE+ (802.3at) switches are used to power them on (PTP820S).

This forum post goes into some additional detail regarding POE options, mostly lower cost options that are used by our other unlicensed PTP products.

More interesting information available here for some specifics on POE requirements.  Again, this would be PTP820S only.

1 Like

Thanks for this input.

Just to make sure, the requirements are the same for PTP820s as are for PTP650? -As stated in in THIS post.

"The PTP 650 can be powered from 802.3at Type 2 (also known as PoE+ or PoE Plus) supplies, providing that:

(a) The power source provides power on the {1,2}{3,6} pairs. This is called "Alternative-A". PTP 650 are not compatible with "Alternative-B".

(b) The power source applies power without waiting for negotiation with the ODU sometimes referred to as passive or legacy mode

(c) The power source has sufficient capacity for the power used by the ODU.

(d) The length of the power cable is not more than 100 m."

Kind regards

The PTP820S and PTP6x0 don't use the same power scheme and are technically not standards based.  However, there are instances where standards based power schemes (802.11at) will power on the devices, with caveats.  I've heard of customers using POE switches, such as Netonix, to power on PTP820S', but unfortunately I can't say for 100% certainty that it will work.  Since the indoor PTP6x0 Power supply can power on the PTP820S, as well as, our 802.3at standards based 450i, I think there is a good chance that the PTP820S can be powered off 802.3at, specifically switches that support Alternative-A.

1 Like

For those who are wondering about POE switches to power the PTP820:

The Cambium supplied POE injector (N000065L001C) provides power on all 8 pins:

1,2,7,8 = Neg (-)

3,4,5,6 = Pos (+)

As mentioned by Chris_Fikert, this technically does not comply to any standard... 

However, I am currently powering a PTP820S on my desk using a passive POE injector at 49.6V on pins: 7,8 (Neg) & 4,5 (Pos) which are "Standard" POE Pins.  The unit is a 15GHz model and running at full power (18dBm), it is drawing 0.62A (i.e. using 30.75W)...

The only drawback it this stage is that i can only make a 100Mbps ethernet connection to the device in this mode. For be this is not an issue, as we are only using a 7MHz channel.  FYI - I have just powered the unit again with it's proper POE injector and now have 1Gbps (using the same patch cables).

I have not yet tested passive POE over a 100m CAT5/6 cable (voltage drop may be an issue over the 2 pairs).
We have ordered some 802.3at or newer POE switches which should be in, in a week or two and will update the post then.

We have just received in our new POE++ switches (Netonix) and bench tested these on a PTP820S (15GHz) with the following parameters:

1.  Output power @ 18dBm (max for this freq band)

2.  105m of CAT5 cable on a spool.

3.  POE standard = 802.11at (mode B) with 7,8 = Neg (-) and 4,5 = Pos (+)...

The results are as follows:

1.  PTP820s powered up all good and working as expected.

2.  POE output at switch = 49.3V

3.  PTP820s reporting 44V at input after 105m of CAT5 (measured 44.5V with multimeter on breakout just before ODU, while still powered).

4.  Switch reporting 36.5W once PTP fully booted and transmitting...

Cheerio people, be kind to each other


PS:  No plan survives first contact with implementation.

1 Like