[Amps] "N, " "TNC" and "BNC" connectors are rated at 500 Watts and work at 1, 000 Watts as log as the load is good..

[Dr. David Kirkby]

On 11 November 2013 08:04, Roger (K8RI) <k8ri at rogerhalstead.com> wrote:
> On 11/11/2013 2:03 AM, Charles Harpole wrote:
>>
>> Notice that the Alpha 76a warns to put no more than 100 watts thru it on
>> stand by.
>
>
> Having used, misused, and abused N-type connectors, experience in the real
> world has shown me that these are not connectors to use for QRO. Yes, I know
> hams who have used them at the legal limit for years,
>
> I have found N-type will run the legal limit if the SWR is low AND to you
> QRO is not 1 watt over the 1500 and usually at the end of several hundred
> feet of inexpensive coax.
>
> With a center fed, sloping dipole, which is far from being a balanced
> antenna, I have blown Male and the double female connectors by moving 50 to
> 100 KHz off resonance.  I've also had nearby lightening strikes take them
> out.

I suspect part of the problem is that they are often not assembled
properly. Often the male or female are too far forward or too far
back, which gives a less than optimal electrical contacts, and I
suspect thermal contact too.

I've got a Maury Microwave connector gage for BNC, TNC and N types. It
indicates the depth of the centre pins with a resolution of 0.001".
These gages measure the depth relative to a master block, which has
the correct depth as defined by the relevant MIL standard. The effect
of a small gap between the male and female does not have a significant
effect on the return loss below a GHz or so, but I suspect it does
have a significant impact on the thermal properties.

You only have to look at a large collection of cables with N
connectors and can visually see the centre pins are often off-centre,
or look in a different position. I don'[t think many people even know
connector gages exist, let alone actually own them and use them.

> I'd prefer DIN 7-16 connectors, but haven't found a source at reasonable
> prices.  Although their construction is such that a small shop could easily
> copy the design.

They are often on eBay.

I bought a low power 50 Ohm 18 GHz N termination off of eBay a week or
two ago. It had an N->7/16 adapter on it, which I was a bit worried
about, but deceided to not ask too many questions, buy it and remove
the adapter.

http://www.ebay.com/itm/181237524149

So I effectively got a free adapter. I did wonder why one would put a
precision male load on a 7/16 adapter, but the load was ok.

Dave