[time-nuts] connectors Re: FW: Re: Low-Cost 6+ GHz Prescaler board for
brooke at pacific.net
Fri Mar 26 14:12:25 UTC 2010
When HP came out with the first VNA (8410) I attended one of the demos.
Part of that was testing a BNC cable over the microwave range. It
worked much better than I expected. It turns out that the cores of a
type-N, TNC and BNC connector are all the same and they will properly
interface with each other (after some modification to allow it). The
problem with panel mount BNC connectors is the back side where the
impedance is not controlled. If you use a panel mount BNC-BNC connector
it's impedance is quite good.
Trompeter used to make a series of connectors (N, TNC, BNC) that all had
the same panel side outline. I used them in a family of Wilkinson power
> John Allen wrote:
>> A few notes about the connector.
>> First, I hate BNC connectors.
>> But the BNC is useable to 11 GHz (No vswr spec.), and has a VSWR
>> spec. of 1.3:1
>> up to 4 GHz. (See link below, about half way down the page.)
>> The application is not a precision one except for frequency - Power
>> inaccuracy due to return loss is not a big deal here, we are not
>> using it in a
>> VNA or power meter etc.
>> PS: Would anybody be interested in testing an SMA to BNC-F and BNC-M
>> to SMA pair
>> on a VNA?
>> Further, some BNC adapters (to SMA) are specified. to 8 GHz. With
>> 1.25:1 VSWR
>> Also - here is a BNC to SMA bulkhead with 10 GHz VSWR max of 1.4:1
>> http://www.fairviewmicrowave.com/adaptersbncsma.htm (Bottom middle).
>> Now if only we could find a SMA to SMA bulkhead that fit in a BNC
>> John Allen K1AE
> I think I've seen hermetic sealed feedthrough for applications like
> vacuum chambers that fit in a larger than normal hole. But they're
> probably also really, really expensive.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> and follow the instructions there.
More information about the time-nuts