[time-nuts] GPS timing antenna 5 meter BNC Plug with cable

Dr. David Kirkby drkirkby at gmail.com
Fri Dec 6 11:20:30 EST 2013


On 6 December 2013 07:52, Tom Knox <actast at hotmail.com> wrote:
> Amazing how reasonable some of these Chinese cables and other electronics are. The quality is also constantly improving.

Though a lot is still poor. I got some adapters recently, and they are
basically only fit for the bin.

> At 40GHz bandwidth the 2.4mm connectors require precision machining. In addition the cable will need to act as a waveguide beyond about 30Ghz. Needless to say they will always command some serious money.  If you are going to that expense I would recommend 2.4mm to 2.4mm with a 2.4mm to 3.5mm adpater. An SMA connector will limit the cable to use below 20GHz.

I want to work to 20 GHz only. It does need to be SMA, as I want to
get direct receiver access on my VNA (8720D)., This was availalble
from Agilent when the instrument was supported. It was option 012. It
routed a few connections between internal parts of the VNA which are
in 2.4 mm, and routes them to the front panel in SMA.

In theory I could do it in 3.5 mm, but then the VNA would be
non-standard and Agilent might refuse to calibrate it. There are 6
cables needed, along with a new front panel overlay. Agilent have them
all except one cable. So I can't perform the upgrade.

The use of the SMAs does cause a slight degraduation in one of the
specs of the VNA, but the advantages would more than make up for that
one thing.

I'll give some thought to the 3.5 mm idea. In principle I could do it
all in 2.4 mm in the VNA, have found 2.4 mm jumps on the front panel,
and put an adapter when I need it. But if Agilent needed to disconnect
those cables during calibration, they might refuse to calibrate it.

> Skip at RDR has had some new surplus 2.4mm cables recently. He may still have some longer lengths.

Where is the web site for RDR - it is not a company I know of, and a
Google did not find it.

I only want 75-100 mm. Any longer would probably be a bad idea.

> They are not $6, but they were reasonably priced and very nice.

I don't mind paying $7. No seriously, I know they wont be cheap.
Agilent want  $100-$300 for the other 2.4 mm to SMA cables, though
they are pre-formed. I would need to bend a cable quite close to the
SMA connector, which is a bit worrying, especially as I don't have a
either a 2.4 or SMA connector gage - although I do have 3.5 mm gages.

Dave

> Thomas Knox
>
>
>> Date: Thu, 5 Dec 2013 16:31:13 +0000
>> From: drkirkby at gmail.com
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] GPS timing antenna 5 meter BNC Plug with cable
>>
>> On 5 December 2013 05:56, David J Taylor <david-taylor at blueyonder.co.uk> wrote:
>> > Anyone know whether these antennas are any good?  Anyone used one?  I wonder
>> > where they are made?
>> >
>> >
>> > http://www.rfsupplier.com/timing-antenna-meter-plug-with-rg58-coax-cable-p-2344.html
>> >
>> > Looks like it has no filter, and some of the spelling is dubious!
>> >
>> > Thanks,
>> > David
>>
>> Reading the site
>>
>> "Rfsupplier is a online b2c company located in Shenzhen, China which
>> specialized..."
>>
>> I agree the English is odd, but it is better than my Chinese.
>>
>> Its an interesting site that will make cables of arbitrary length with
>> arbitrary connectors, though I think they might struggle to make this
>> cable they quote $6 for.
>>
>> "Product: Cable Type: RG8; Length: 0.1cm/0.04inch(s); Connector A: N
>> Straight Jack; Connector B: N Right Angle Plug"
>>
>> I wish I could find a similar site that would make me a cable with a
>> 2.4 mm male plug at one end, and a female chassis mount SMA on the
>> other. I suspect a company like Huber and Suhner could make me one,
>> but I suspect it would be a small fortune for a one-off.
>>
>> Dave
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-- 
Dr. David Kirkby G8WRB
http://www.vnacalibration.co.uk/
Economical & accurate VNA calibration kits.
Coefficients available for HP, Agilent, Anritsu, Rohde & Schwarz and
VNWA network analyzers.


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