Date   

Re: 23 cm Yagi Design

Peter
 

Personally, I have had success using the DL6WU Yagi designs at 23 cm.

Simply use the VK5DJ Yagi Calculator, available for download to install in a Windows PC. Carefully consider your material sizes, and simply plug the material sizes into the calculator. Then measure, drill and cut with care. I have a short Yagi built according to the calculator using 4 mm rod for elements and a 20 mm PVC pipe as the boom. It works well for SOTA. Longer Yagis work well if carefully built.

Cheers,

Peter VK3PF


23 cm Yagi Design

Barry VE4MA
 

A corner reflector is a good but low gain option.   Loop yagis of all sizes are the antennas of choice in North America.  Good all weather performance ( yagis are problematic in wet weather).

Element kits are available from Directive Systems in the US at reasonable prices

73
Barry VE4MA/ K7


Re: 23 cm yagi design

Alan Beard
 

Hi guys,

Would we do better at 23cm building a corner reflector?

I built a truncated corner reflector out of a 600 x 900 mesh sheet,
1mm gal wire 20mm mesh. I used two end fed dipoles (or 5/8s)
fed from a trombone match. It seemed to work about as well as
a 12el phased array.
Obviously it's much more 3D than a "flat" yagi. But I recognized
I couldn't build a yagi to the tolerances needed.
Very poor test gear here, a PocketVNA.

Alan VK2ZIW



On Tue, 21 Jan 2020 23:29:56 +0000, Chris Bartram G4DGU wrote
Hello Ben,

Is there any advantage to making the reflector either multi-element,
several elements above and below the boom, either at 90deg to the boom
or in a V shape pointing along the boom?
Essentially no! Yagies for the low microwave bands are very
difficult to get to work very well. I speak from experience :-) My
last design for 1296 which looked good in simulation took a lot of
work to get working properly, as shown by Sun and cold-sky/ground measurements.

Having used both yagies and dishes on 23 over time, I won't be
building a new yagi system for any band above above 432MHz.

73

Chris G4DGU - who you last worked as GW4DGU on 5MHz AM! There's an
admission!


---------------------------------------------------
Alan Beard

OpenWebMail 2.53


Re: 23 cm yagi design

Chris Bartram G4DGU
 

Hello Ben,

Is there any advantage to making the reflector either multi-element, several elements above and below the boom, either at 90deg to the boom or in a V shape pointing along the boom?
Essentially no! Yagies for the low microwave bands are very difficult to get to work very well. I speak from experience :-) My last design for 1296 which looked good in simulation took a lot of work to get working properly, as shown by Sun and cold-sky/ground measurements.

Having used both yagies and dishes on 23 over time, I won't be building a new yagi system for any band above above 432MHz.

73

Chris G4DGU - who you last worked as GW4DGU on 5MHz AM! There's an admission!


Re: 23 cm yagi design

KENT BRITAIN
 




If the other elements are optimized ...... NO.

Kent


Needed the plural form





On Tuesday, January 21, 2020, 4:35:43 PM CST, militaryoperator via Groups.Io <military1944@...> wrote:



Regarding 23cm yagi's. 

Is there any advantage to making the reflector either multi-element, several elements above and below the boom, either at 90deg to the boom or in a V shape pointing along the boom?

Ben


Re: 23 cm yagi design

KENT BRITAIN
 

If the other element are optimized ...... NO.

Kent

On Tuesday, January 21, 2020, 4:35:43 PM CST, militaryoperator via Groups.Io <military1944@...> wrote:



Regarding 23cm yagi's. 

Is there any advantage to making the reflector either multi-element, several elements above and below the boom, either at 90deg to the boom or in a V shape pointing along the boom?

Ben


Re: 23 cm yagi design

militaryoperator
 


Regarding 23cm yagi's. 

Is there any advantage to making the reflector either multi-element, several elements above and below the boom, either at 90deg to the boom or in a V shape pointing along the boom?

Ben


Spectrum Analyser conundrum

Andy G4JNT
 

Openly Pondering ...

My Ailtech / Eaton 757   22GHz spectrum analyser has died.   Now, I could just dig inside and repair it - looks like the main PSU has failed somewhere, so probably is repairable, and I hate repairing stuff, especially old tech.   ANd then there's all the niggly faults which appeared over time, probably dried out capacitors to be  replaced.   The thing weighs over 30kg has already hurt my back in days gone by and is too long in the tooth and irritating to drive

I'd buy a half- decent SA but many popular ones only go to a few GHz and 22GHz ones are not cheap. I already have a modern digital radio test set that has a quite good narrow band SA function that goes to 6GHz  with span up to a GHz, so spending a fair bit of money on an SA that doesn't go much beyond this seems totally pointless.

NOW ...

I have two old YIG filters that tune 4 - 18GHz.  The Ailtech will have another one inside it, as well as a harmonic mixer so thoughts are turning to an external converter.    YIG filter, harmonic mixer and integer-N synth LO with some basic drive electronics.   Simple enough.   Could butcher the old SA for it's harmonic mixer, or make one using a uWave DBM with subharmonic LO.  It also has the switchable attenuator going to 20GHz + and possibly other uWave bits that may prove useful

So the decision to repair (tedious and not exciting) or rip apart for bits to make an external converter has to be made,

Has anyone done this - an external SA convertger?   Might generate a bit of interest in building RF stuff again here !

 


Re: 13cms operation

Ed G3VPF
 

Thanks for the replies, e-mail duly sent to Ofcom. Perhaps the RSGB bandplans could include the link to the Ofcom document.

Waiting for 13cms PA to arrive from SG-Labs but should be on for the coming contest season.

Ed G3VPF IO80RQ


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of Neil Smith G4DBN <neil@...>
Sent: 21 January 2020 13:40
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] 13cms operation
 

Thanks for the reminder that the 2300 MHz NoVs need renewing after 3 years.  Mine was due to run out, so I renewed it.  You just need your licence reference number and details of any /P locations you intend to use.

Neil G4DBN

On 21/01/2020 13:13, Murray Niman wrote:

Hi Stuart

>"The UK Amateur Licence Schedules have a number of designated zones where restrictions apply"
Please read Schedule-2 of your Licence - the map is what that table is when you plot it!

More uptodate mapping guidance is on
https://rsgb.org/main/operating/licensing-novs-visitors/uk-licensing/guidance-resources/

 Murray G6JYB
-- 
Neil
<a href="http://g4dbn.uk/"><small>g4dbn.uk</small></a>


Re: Input Needed for RadCom Column

John Worsnop
 

I should add that any GHz stuff that won't fit in to my 1 page will usually get in to Scatterpoint via me if you don't send it to editor@....

As I've said many times to people, if you want a larger GHz Bands column,  email radcom@... and ask for one. I'm happy to fill a second page.

As Elaine and Giles will tell you, every time I see them (the editors), I ask them for a second page, but the reply is the same.
"The readership doesn't demand it, "our recent survey" showed that GHz Bands is not widely read and was a minority interest....... but you can always write us stand alone articles" (Which I do!)

73

John   

On Tue, 21 Jan 2020 at 17:25, Andy G4JNT <andy.g4jnt@...> wrote:

Microwave input really ought to go in the uWaves / GHz column,  so John ought to get first dibs on anything.  But as I have three pages every month, and GHz has one, there's space for more so  ....................

It is getting more and more difficult to find interesting RF and Am. Radio related matters to write about for the regular three pages of Design Notes in RadCom every month.  'JNT labs own projects are running out of steam, and to be quite brutal about things, I personally am getting less and less interested in RF related matters altogether.   What interest remains is purely software / DSP and non radio related electronics.  Very little of which will form DN-suitable material.  

SO........

It really would help if I had input from readers.  What are you doing, bright ideas, helpful tips and hints etc.   Pat Hawker's old column, Tech Topics was made up entirely from reader input and stuff blatantly culled from other publications.   The latter is now pointless with 't web and I'm not even going tp consider that route.   So that leaves reader input.

Please send me your input as and when.  Most reader input will be pasted in directly, with a minimum of editing for correctness / grammar etc.   And naturally you'll be credited.

 OR ......

Although it doesn't help with DN, consider writing up your work as a standalone article for RadCom (or ...Plus   or ...Basics)  .  That way you'll see your work in print and get paid for it.    


Input Needed for RadCom Column

Andy G4JNT
 


Microwave input really ought to go in the uWaves / GHz column,  so John ought to get first dibs on anything.  But as I have three pages every month, and GHz has one, there's space for more so  ....................

It is getting more and more difficult to find interesting RF and Am. Radio related matters to write about for the regular three pages of Design Notes in RadCom every month.  'JNT labs own projects are running out of steam, and to be quite brutal about things, I personally am getting less and less interested in RF related matters altogether.   What interest remains is purely software / DSP and non radio related electronics.  Very little of which will form DN-suitable material.  

SO........

It really would help if I had input from readers.  What are you doing, bright ideas, helpful tips and hints etc.   Pat Hawker's old column, Tech Topics was made up entirely from reader input and stuff blatantly culled from other publications.   The latter is now pointless with 't web and I'm not even going tp consider that route.   So that leaves reader input.

Please send me your input as and when.  Most reader input will be pasted in directly, with a minimum of editing for correctness / grammar etc.   And naturally you'll be credited.

 OR ......

Although it doesn't help with DN, consider writing up your work as a standalone article for RadCom (or ...Plus   or ...Basics)  .  That way you'll see your work in print and get paid for it.    


Midland RT & Heelweg

Roger Ray
 

Input for Scatterpoint

Does anyone have a report and or pictures from the Midland Round Table, and Heelweg?

Thanks

Roger


Re: Dishes and wind

Paul Randall G3NJV
 

I think that picture shows the elevation actuator has been removed.
Paul


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of Alan Beard <beardal@...>
Sent: 16 January 2020 10:00
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Dishes and wind
 
Taken on Ponape, Federated States of Melanesia 

What happens if the wind blows the wrong way???

Taken in 2010

Alan VK2ZIW

On Wed, 15 Jan 2020 10:24:03 +0000, alwyn.seeds1 wrote
> The same Husband & Co. that did the structural design for Jodrell Bank.
>

> Interesting description of the issues faced in [UTF-8?]Lovell’s book [UTF-8?]“The Story of Jodrell [UTF-8?]Bank�.
>

> 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.
> _____________________________________________________


---------------------------------------------------
Alan Beard

OpenWebMail 2.53


Re: 13cms operation

Neil Smith G4DBN
 

Thanks for the reminder that the 2300 MHz NoVs need renewing after 3 years.  Mine was due to run out, so I renewed it.  You just need your licence reference number and details of any /P locations you intend to use.

Neil G4DBN

On 21/01/2020 13:13, Murray Niman wrote:

Hi Stuart

>"The UK Amateur Licence Schedules have a number of designated zones where restrictions apply"
Please read Schedule-2 of your Licence - the map is what that table is when you plot it!

More uptodate mapping guidance is on
https://rsgb.org/main/operating/licensing-novs-visitors/uk-licensing/guidance-resources/

 Murray G6JYB
-- 
Neil
<a href="http://g4dbn.uk/"><small>g4dbn.uk</small></a>


Re: 13cms operation

Murray Niman
 


Hi Stuart

>"The UK Amateur Licence Schedules have a number of designated zones where restrictions apply"
Please read Schedule-2 of your Licence - the map is what that table is when you plot it!

More uptodate mapping guidance is on
https://rsgb.org/main/operating/licensing-novs-visitors/uk-licensing/guidance-resources/

 Murray G6JYB


Re: FT290-490 mic

Paul G8AQA
 

On 20/01/2020 16:54, Chris Bartram G4DGU wrote:
Thanks for all the interest folks. As I suggested in my original email, the microphone has gone to the first person to get their address to me ...

There is clearly a market for microphones for the 290/790!

73

Chris

G4DGU




Re: 13cms operation

Stuart G1ZAR
 

On a similar line to the OP.
I shall soon be moving house and the new QTH will be in an area covered by one of the restricted zones.
"The UK Amateur Licence Schedules have a number of designated zones where restrictions apply"

https://www.microwavers.org/maps/license.htm

I have read through a version of the schedule downloaded from Ofcom, but cannot find the information on these (apart from Charing Cross).
Where can I find the required info, and could some further guidance or links be added to the map?
e.g. Charing cross states 431-432MHz 100km radius on the map, but the others only show grid ref and locator.

thank you
Stuart
G1ZAR


Re: Using a HP8484A with HP436a

Lou Blasco
 

Hi All,

I couldn't wait until the weekend so got out early this morning to see what was going on with the 436. Short story, one of the op-amps on the AC gain board was dead, output stuck low. U4 is a NS1826-0161 which can be replaced with a LM324. Bit of an anti-climax really, the meter just works as expected. 

For those that enjoy troubleshooting, U4A pin 1 was the culprit and as it happens is the only bit in a 4 bit word that needs to change to select a -20dBm sensor instead of a +20dBm sensor. They use the op-amp to generate these 4 bits by using different value resistors in the sensors to cover 10uW to 100W sensors. Quite ingenious really. The four bits feed high order bits of a ROM to do the range selection.

Thanks to all that responded, it was an interesting exercise.


image.png
 
Regards

Lou
VK3ALB


On Mon, Jan 20, 2020 at 10:53 PM Lou Blasco via Groups.Io <vk3alb=gmail.com@groups.io> wrote:
Hi Rainer,

Indeed not all the pins exist in this particular cable. Whilst there is good continuity on all wires there is only one ground wire (F) in this particular assembly and pins A, M, J are missing. The 10K sensor resistance can be measured between pins K and F. This evening I took the cable and sensor to a friend's house and confirmed they both work as expected in his 436. As the sensor resistor is detected in my friend's 436 and my 8901 I am confident that the issue lies in my 436. It's late in the evening here and no time to tear down the meter. I will have more time on the weekend to tackle this problem. Thanks for your interest and investigations and thanks to those of you that have replied so far. I will update everyone when I have more.
 
Regards

Lou
VK3ALB


On Mon, Jan 20, 2020 at 9:58 PM DF6NA Rainer <df6na@...> wrote:
Hi Lou,

the cables for the 435A are not wired on all PINs ! When you use such cable the 436A can not detect the sensor.
You need ALL Pins connected. You can check K, A, F, M, J with an OHM-Meter.

73, Rainer

Am 19.01.2020 um 22:32 schrieb Lou Blasco:
Hi Rainer,

I am using the same 11730A cable for both meters. Whilst not specifically mentioned in the 435 or 436 manuals I assume the variations in 11730 (A thru F) are simply cable length. Both manuals also lists the HP8484A so I assume that these suitable for use with either meter. Additionally, the cable and probes all work as expected with the HP435 so I'm leaning towards some kind of issue with the meter - either fault or limitation. 

Regards

Lou
VK3ALB


On Mon, Jan 20, 2020 at 8:09 AM DF6NA Rainer <df6na@...> wrote:
Hi,

you don't say what cable you are using. I guess it's the wrong cable for the 436A and the 436A thinks it has a different head!

73, Rainer


Am 19.01.2020 um 21:55 schrieb Lou Blasco:
Hi all,

I was trying to use a 8484A sensor with my 436a and found an anomaly. The issue is the reference cal reads +10dBm instead of 0dBm. 

My presumption is that either the meter cannot deal with the sensor correctly or there is something wrong with my meter. I have an 8481 and 8482 sensor which both behave correctly with the 436a.  I think my tests below point towards the an issue of some kind with the meter.

Haven't found anything on Google to confirm it but perhaps someone here with the same kit might be kind enough to check what I see.   

HP8484A connected to 11708A ref attenuator connected to the HP435 and it's internal reference reads -30dBm full scale.

HP8484A connected to 11708A ref attenuator connected to the HP435 and the 436 internal reference reads -30dBm full scale. 

HP8484A connected to 11708A ref attenuator connected to the HP436 and it's internal reference reads +10dBm. 

HP8484A connected to 11708A ref attenuator connected to the HP436 and the 435 internal reference reads +10dBm.

Regards

Lou
VK3ALB



Re: 13cms operation

Murray Niman
 

The RSGB online bandplan has this detail too
https://rsgb.org/main/operating/band-plans/microwaves/spectrum-release/

Further sharing has occurred since, so we do try to be careful in 13cm

73

   Murray G6JYB 


Re: 13cms operation

John Quarmby
 

Hi Ed


See this document:

https://www.ofcom.org.uk/__data/assets/pdf_file/0025/79810/pssr_amateur_statement.pdf


In particular section 5, and para 5.34 on page 36


73


John G3XDY


On 20/01/2020 21:43, Ed G3VPF wrote:
As a newcomer to 13cms I am somewhat confused by the recently published contest rules for Microwave Group contests. I understand the need for an NoV to operate on 2300MHz, but don't understand the need to supply Ofcom with a long list of information for operation on 2320MHz. I checked the Ofcom website which does not show this requirement in the licence schedule, and the RSGB bandplan which also does not show this requirement.

Have I missed something?

Ed G3VPF IO80RQ

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