advice on buying second-hand network analyzer [title edited]

[bug13]

Hi guys

I want to get more hand on, and learn about more about antenna matching and tuning, so I need a VNA. New ones are too expensive for me, so I want to get my hand on a second one. second-hand one. (didn't know why I typed second one, doh!!)

I see this on ebay:
Keysight Agilent HP 8711C 300 kHz to 1.3 GHz
http://www.ebay.com/itm/Keysight-Ag...530939?hash=item28223416fb:g:6toAAOSwYIxX~jTQ
correct link:
http://www.ebay.com/itm/Keysight-Agilent-HP-8711C-300-kHz-to-1-3-GHz-Network-Analyzer-30-Day-Warranty-/172372530939

What do you guys think? I would love you hear your advice/suggestion before parting my money.

Cheers.

James

[KD0CAC John]

You need to double check your link , it does go to eBay - but no results ?
There is other options that can be new and cost less than either $500 or $1,000 , many are tied to using a computer to use .
For that range , one is the miniVNA Tiny   http://miniradiosolutions.com/54-2/
I have had the miniVNA Pro for some yrs. , not as high in frequency coverage .

[Teuobk]

Are you maybe linking to this one?

http://www.ebay.com/itm/Keysight-Agilent-HP-8711C-300-kHz-to-1-3-GHz-Network-Analyzer-30-Day-Warranty-/172372530939

If so, a few thoughts:

• That's a 75 ohm input impedance model, so if you want to use it to characterize 50 ohm devices you'll need a "minimum loss pad"
• The HP 8710 series of VNAs provides decent performance. Not super-high performance, but totally fine for most things you'd want.
• That one has a T/R test set, so if you want to do full S-parameter measurements, you'll need to do some cable swapping
• The full CLIP (schematics, etc.) for the 8711C is available, so if something were to break, you'd have a good shot of diagnosing and fixing it

I have a 8714ES, and I've been very happy with it (after I repaired it).

[bug13]

Hi John,

miniVNA look interesting, I think it may be better suit for me, thanks for the info. PS: the link is fixed.

[bug13]

Hi Teuobk

I think the 75Ohm impedance really turn me off, all the stuff I am interested in are 50Ohm, thanks for pointing this out, it helps me a lot. Thanks for your replay!!

[BigBoss]

It's not a VNA, it's just a Scalar Network Analyzer.You cannot measure impedances in complex form on the Smith Chart.
That's why it's very cheap..

[Teuobk]

It's not a VNA, it's just a Scalar Network Analyzer.You cannot measure impedances in complex form on the Smith Chart.
That's why it's very cheap..

Interesting. I checked the datasheet, and you're correct: the 8711C is a scalar network analyzer. The 8712 and 8714 are proper vector network analyzers, with Smith charts, complex impedance, etc., so I had assumed the whole 8710 series were VNAs -- nope! Good to know.

[bozidarms]

Hi,
give a try to - 1.3 GHz DG8SAQ Vector Network Analyzer   VNWA3E  -,
it is more than adequate.
Regards

[BigBoss]

It's not a VNA, it's just a Scalar Network Analyzer.You cannot measure impedances in complex form on the Smith Chart.
That's why it's very cheap..

Interesting. I checked the datasheet, and you're correct: the 8711C is a scalar network analyzer. The 8712 and 8714 are proper vector network analyzers, with Smith charts, complex impedance, etc., so I had assumed the whole 8710 series were VNAs -- nope! Good to know.

If you can find old stuff 8720C, it's really good VNA ( I used for years) but it may be a bit pricey.

[KJDS]

It's not a VNA, it's just a Scalar Network Analyzer.You cannot measure impedances in complex form on the Smith Chart.
That's why it's very cheap..

Interesting. I checked the datasheet, and you're correct: the 8711C is a scalar network analyzer. The 8712 and 8714 are proper vector network analyzers, with Smith charts, complex impedance, etc., so I had assumed the whole 8710 series were VNAs -- nope! Good to know.

The 8711C and the 8713 are vector network analyzers, however they only displays scalar information. It is possible to suck the vector info from the GPIB port.

[TheSteve]

You can also convert the 8711x series to a 8712x with a small firmware change to a socketed chip.

[BigBoss]

The 8711C and the 8713 are vector network analyzers, however they only displays scalar information. It is possible to suck the vector info from the GPIB port.

If it's so why this equipment does not show the vector information on the screen??? I don't think that is so easy.
Vector information is more complicated than scalar one.The equipment should measure "the Phase" that is more complex.
 

[KJDS]

The 8711C and the 8713 are vector network analyzers, however they only displays scalar information. It is possible to suck the vector info from the GPIB port.

If it's so why this equipment does not show the vector information on the screen??? I don't think that is so easy.
Vector information is more complicated than scalar one.The equipment should measure "the Phase" that is more complex.

You'll have to ask Keysight why it doesn't show the phase data on the screen.

[TheSteve]

8711/8712 are the same hardware just as 8713/8714 are. The display of vector information was simply disabled on screen on the cheaper models. As was already stated it has always been available via the GPIB port. Or a change to the internal eeprom will upgrade an 8711 to a 8712 or an 8713 to a 8714. With the upgrade all vector information is available on screen.

[hendorog]

FWIW I made an offer a while back of $430 on that auction. Seller never came back to me.

[chrisl]

The 8711C and the 8713 are vector network analyzers, however they only displays scalar information. It is possible to suck the vector info from the GPIB port.

If it's so why this equipment does not show the vector information on the screen??? I don't think that is so easy.
Vector information is more complicated than scalar one.The equipment should measure "the Phase" that is more complex.

Looks like this is very doable... no idea how.
http://minolta1.cninet.cz/HP8712C/