Topics

Wimo 13cms aerial VSWR


Ed G3VPF
 

Sorry to start a new thread but Groups.io rejected my attempts to reply to the old thread!

Many thanks for the replies so far. Once the weather improves I will set things up on the lawn and have a play with the various ideas. Currently bitterly cold with horizontal drizzle - not ideal for playing with aerials.

Sam - which VNA's are OK on 13cms? At present only test gear I have is the directional coupler  built into the transverter. Had a quick look on the internet but only found two that claimed to work at 2.3GHz, of which only the Mini-VNA was reasonably priced.

Ed
 G3VPF IO80RQ


SAM JEWELL
 

Ed,
Hardly a recommendation....I use an HP 5753C and S parameter test set. The price was good!
Calibration is done at the end of the test cable using professional SOT calibration and a good test cable.
I purposely said that the cheapies didn’t allow ‘measurement’ at 2.3GHz, but the indications can still be useful.
It’s all down to how good the directivity is of whatever the ‘device’ is that is discriminating the direction of signal ‘flow’.
It goes without saying that when the VNA is not directly connected to the antenna feedpoint, and a coax cable is used, then it is necessary to calibrate at the antenna end of the connecting cable, using a good, known, cal kit SOT set.

I find it useful to test with various good quality Attenuators at the end of the cable. The attenuators are terminated in a short (or open) to minimise fringing effects. 3 and 6dB attenuators should read close to twice their attenuation. 10dB and higher will probably show increasing error.  Calibrated mismatches are harder to find but can be made, but will need calibrating with a known, good  VNA.

I hope that helps?

73 de Sam

On Friday, November 15, 2019, 4:17 pm, Ed G3VPF <g3vpf@...> wrote:

Sorry to start a new thread but Groups.io rejected my attempts to reply to the old thread!

Many thanks for the replies so far. Once the weather improves I will set things up on the lawn and have a play with the various ideas. Currently bitterly cold with horizontal drizzle - not ideal for playing with aerials.

Sam - which VNA's are OK on 13cms? At present only test gear I have is the directional coupler  built into the transverter. Had a quick look on the internet but only found two that claimed to work at 2.3GHz, of which only the Mini-VNA was reasonably priced.

Ed
 G3VPF IO80RQ


alwyn.seeds1
 

Dear All,

Yes, I have always liked the HP8753, but they are not cheap.

Although it is only a scalar analyser, the Anritsu S331 is pretty useful for aerial adjustment.

Also, it’s intended for use by riggers, so is compact lightweight and battery powered, so handy in the field.

A few hundred pounds on e-bay is the typical price.

Regards,

Alwyn

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


G0FVI
 

Just got into microwaves here, I use both a cheap Chinese vna, and a combination of an rf bridge/noise source/sdr receiver. They both show pretty close agreement up to cutoff of the rf Bridge assembly (1.5 Ghz). Would be interesting to compare them beside a decent setup, suffice to say swr lights on my sg lab transverters (2.4 and 1.3Ghz) are always happy. 
As regards the wimo, I would say do check all the elements too. I have a 37 ele recently aquired for 23cm. Two of the elements had been placed in wrong order (might have been previous owner!), causing the useable bandwidth to become very narrow. 

Sent from my Huawei phone


-------- Original Message --------
Subject: Re: [UKMicrowaves] Wimo 13cms aerial VSWR
From: "alwyn.seeds1"
To: "UK Microwaves groups.io"
CC:

Dear All,

Yes, I have always liked the HP8753, but they are not cheap.

Although it is only a scalar analyser, the Anritsu S331 is pretty useful for aerial adjustment.

Also, it’s intended for use by riggers, so is compact lightweight and battery powered, so handy in the field.

A few hundred pounds on e-bay is the typical price.

Regards,

Alwyn

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Conrad, PA5Y
 

Alwyn the S331 is indeed useful and unlike it's cheaper predecessor the S251,  has an acceptable frequency accuracy the S251 was 200ppm I seem to recall which is not great on 13cms. However where can you get an S331 for a few hundred pounds? 

I would sell my IC-7300 to get an S331!

73

Conrad PA5Y


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of alwyn.seeds1 via Groups.Io <a.seeds@...>
Sent: 15 November 2019 22:23
To: UK Microwaves groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Wimo 13cms aerial VSWR
 
Dear All,

Yes, I have always liked the HP8753, but they are not cheap.

Although it is only a scalar analyser, the Anritsu S331 is pretty useful for aerial adjustment.

Also, it’s intended for use by riggers, so is compact lightweight and battery powered, so handy in the field.

A few hundred pounds on e-bay is the typical price.

Regards,

Alwyn

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Lou Blasco
 

Hi all,

A quick check on ebay shows later S331 available from 1300 to 3500 GBP. There are others available for much, much less but one wonders about the state of them and shipping gear around the world in case of trouble is not appealing.

Whilst not really a portable device, I've been using a TPI-1001B generator for scalar measurements to 3500MHz and I'm very pleased with the results. Of course, results depend on the quality of your coupler, cables etc.

https://rf-consultant.com/products/tpi-1001-b-signal-generator/

A great feature is the capacity to store your last used generator settings. This means you can put it at the far end of the antenna range to use as the source TX.

Just sayin'

Regards

Lou
VK3ALB




At 00:59 19/11/2019, you wrote:
Alwyn the S331 is indeed useful and unlike it's cheaper predecessor the S251,  has an acceptable frequency accuracy the S251 was 200ppm I seem to recall which is not great on 13cms. However where can you get an S331 for a few hundred pounds?

I would sell my IC-7300 to get an S331!

73

Conrad PA5Y


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of alwyn.seeds1 via Groups.Io <a.seeds@...>
Sent: 15 November 2019 22:23
To: UK Microwaves groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Wimo 13cms aerial VSWR

 
Dear All,

Yes, I have always liked the HP8753, but they are not cheap.

Although it is only a scalar analyser, the Anritsu S331 is pretty useful for aerial adjustment.

Also, its intended for use by riggers, so is compact lightweight and battery powered, so handy in the field.

A few hundred pounds on e-bay is the typical price.

Regards,

Alwyn

_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


alwyn.seeds1
 

Dear Conrad,

For the S331 and similar models watch e-bay carefully; I’ve so far bought two at prices ranging from £220 for an S331B to £364 for an S331D with black and white screen and internal power meter.

The S331 models with colour screens go for higher prices, but the measured data are just the same.

Test equipment dealers push for high prices, of course; but riggers hanging up their climbing boots are far more reasonable.

The battery is usually dead, so that costs an extra £80 if you want one with the internal charge monitor interface or £40 without.

Of course, you also need to buy calibration open, short and load, good to the max frequency and they will cost maybe another £150 in total for good samples.

So you’d have plenty of change from selling your ‘7300!

Regards,

Alwyn


_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________