Date   

Re: Bell Hill gardening session

Alan G0XBV
 

Good job, Andy/Neil!  Can I recommend after 1 August another year, just in case there are still blackcaps/whitethroats nesting in there :>)

Al G0XBV


-----Original Message-----
From: Andy Talbot andy.g4jnt@... [ukmicrowaves]
To: Ukmicrowaves (ukmicrowaves@...) ; uk_beacons Sent: Thu, 5 Jul 2018 10:14
Subject: [ukmicrowaves] Bell Hill gardening session

 
Yesterday Neil, G4LDR and myself made an inspection and general clearing and tidy up session around the Bell Hill microwave beacon site.   It hadn't been visited for something like two years,with no proper gardening for even longer and was badly overgrown.


I had intended bringing back the GB3SCS 2.3GHz beacon to modify for JT9F-Fast modulation.  But after all that work apathy set in so I didn't bother extracting the hardware..  It's the wrong time of year for there to be much interest anyway.  I'll do the change later this year so the winter months can be used for testing A/C scatter from it on 2.3 


Re: 23cm JVL quadloop with log periodic feed

Chris G3WIE
 

Thanks Kent and John for your replies,

I do have a W1GHZ ratiometer so some sort of antenna range should be possible. However, my aim is to get on the radio for a change and I won't be building a box of 8 anything! I've already had a suggestion to make a DL6WU yagi as well and compare; perhaps after the first 100 QSOs.

I'll build a simple 2m-long loop yagi first, I have the material to hand and a metal former to roll the elements. In principle I could CNC drill the holes but it'd take longer to set up than the mandraulic method.

73

Chris


Re: Attenuator article

Andy G4JNT
 

Isn't it just easier to remember the equation ;-)

Having said that,   Barry's published equations are different to the ones I hold in my head, but only down to a bit of  rearrangement.  I use :

Rshunt   =   Zo * (1 + A) / (1 - A)   and Rtop  = Zo * (1 - A* A / 2.A

Where A = 10^(- Attenuation / 20)       ie. A less than one]

On 5 July 2018 at 10:33, 'Alan Melia' Alan.Melia@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

Hi Claudio the article is in the archive on the ukmicrowaves web site
http://www.microwavers.org/indexs.htm

It is in the October 2006 issue. The article is basically a print of the
spreadsheet.

Best Wishes
Alan
G3NYK



[uk_beacons] Bell Hill gardening session

alwyn.seeds1
 

 

Dear Andy,

Yes, indeed. I go through the same exercise at my site each year, and this year bramble and ivy growth has been extraordinary. 

Worse still, the sycamores have enjoyed the good levels of rain in the spring and yet another big bill from the tree surgeons is likely, if I am not to waste good RF warming up trees. 

At least, your foliage seems not quite as prickly as what North Oxfordshire offers.

Regards,

Alwyn






Yesterday Neil, G4LDR and myself made an inspection and general clearing and tidy up session around the Bell Hill microwave beacon site.   It hadn't been visited for something like two years,with no proper gardening for even longer and was badly overgrown.


I had intended bringing back the GB3SCS 2.3GHz beacon to modify for JT9F-Fast modulation.  But after all that work apathy set in so I didn't bother extracting the hardware..  It's the wrong time of year for there to be much interest anyway.  I'll do the change later this year so the winter months can be used for testing A/C scatter from it on 2.3 


Attenuator article

Alan Melia
 

Hi Claudio the article is in the archive on the ukmicrowaves web site http://www.microwavers.org/indexs.htm

It is in the October 2006 issue. The article is basically a print of the spreadsheet.

Best Wishes
Alan
G3NYK


Bell Hill gardening session

Andy G4JNT
 

Yesterday Neil, G4LDR and myself made an inspection and general clearing and tidy up session around the Bell Hill microwave beacon site.   It hadn't been visited for something like two years,with no proper gardening for even longer and was badly overgrown.


I had intended bringing back the GB3SCS 2.3GHz beacon to modify for JT9F-Fast modulation.  But after all that work apathy set in so I didn't bother extracting the hardware.  It's the wrong time of year for there to be much interest anyway.  I'll do the change later this year so the winter months can be used for testing A/C scatter from it on 2.3 


Re: 23cm JVL quadloop with log periodic feed

John Fell
 

Chris,
All the advice given is valid regarding antenna design .

From an empirical point of view the G3JVL design was a potent boost to 432 MHZ and upwards when Mike published it in the mid 1970's and allowed reproducible results .
I have built many , used for EME on 432MHZ and contesting on 1.3GHZ . The time taken to reset/optimise the 400 elements of the 8x50 23cm  stacked and bayed array after transportation , eventually proved problematic for that application .First side lobe levels were also higher than conventional Yagis - useful for contesting ....
Mike's commercially produced version , with MIG welding wire loops welded to Hex Head setscrews were much more durable .

When Ian GM3SEK published his notes on the DL6WU double optimised Yagi , during the 1980's , I found that on 23cm 40 el Yagis could be built easily using 6mm rod elements and 300 Ohm folded dipoles with 1/2wave baluns . I still use these at home today. .Gain Bandwidth is reasonably wide and  allows operation over the full band , with useable return loss .

There have no doubt been many "optimised" Yagi designs since those times but I suspect narrower bandwidth is the trade off .

73

John
G0API


On 4 July 2018 at 23:22, KENT BRITAIN WA5VJB@... [ukmicrowaves] <ukmicrowaves@...> wrote:
 

Hi Chris

Your biggest design variable for the impedance of the driven element is
the size and position of the Reflector and Driven Elements.

You can make a Yagi using a simple dipole as the driven element.
72 Ohms, give or take, in freespace.
Position of the other elements (Very wide spacing) loads the 72 down to 50 Ohms.

Or you can take a folded dipole DE, something near 300 Ohms, and with very close spacing
of the first director load it down to 50 Ohms.  F9FT liked to do this on his Yagi's.

I suggest staying with an established design.   But an antenna range is not that hard to put
together and you can have a lot of fun with new designs and tweaks to existing designs.

There are some Wideband 23 cm Yagi's publsihed by Andy  G8ATD a few years ago,
but I haven't had any luck finding my copy this afternoon.

Kent





From: "g3wie@... [ukmicrowaves]" <ukmicrowaves@...>
To: ukmicrowaves@...
Sent: Wednesday, July 4, 2018 4:15 PM
Subject: Re: [ukmicrowaves] 23cm JVL quadloop with log periodic feed

 
Thanks Kent,

Some checking of numbers between the two versions says that, for a given design frequency,  I can build the directors on one section of boom and plug-in a short extra section with either the narrow-band single DE or the log periodic. 

My question about impedance related to the feedline for the 3-loop log periodic section rather than the antenna as a whole. I haven't found any detail of that beyond a sketch, and the calculated dimensions for the spacing of the 3 loops and the length of the s/c stub at the end. Some papers I've found give closed form equations for the impedance, whether they will work for this remains to be seen. I'll build a single-loop DE version first and see how it performs.

73

Chris G3WIE






Re: 23cm JVL quadloop with log periodic feed

KENT BRITAIN
 

Hi Chris

Your biggest design variable for the impedance of the driven element is
the size and position of the Reflector and Driven Elements.

You can make a Yagi using a simple dipole as the driven element.
72 Ohms, give or take, in freespace.
Position of the other elements (Very wide spacing) loads the 72 down to 50 Ohms.

Or you can take a folded dipole DE, something near 300 Ohms, and with very close spacing
of the first director load it down to 50 Ohms.  F9FT liked to do this on his Yagi's.

I suggest staying with an established design.   But an antenna range is not that hard to put
together and you can have a lot of fun with new designs and tweaks to existing designs.

There are some Wideband 23 cm Yagi's publsihed by Andy  G8ATD a few years ago,
but I haven't had any luck finding my copy this afternoon.

Kent





From: "g3wie@... [ukmicrowaves]"
To: ukmicrowaves@...
Sent: Wednesday, July 4, 2018 4:15 PM
Subject: Re: [ukmicrowaves] 23cm JVL quadloop with log periodic feed

 
Thanks Kent,

Some checking of numbers between the two versions says that, for a given design frequency,  I can build the directors on one section of boom and plug-in a short extra section with either the narrow-band single DE or the log periodic. 

My question about impedance related to the feedline for the 3-loop log periodic section rather than the antenna as a whole. I haven't found any detail of that beyond a sketch, and the calculated dimensions for the spacing of the 3 loops and the length of the s/c stub at the end. Some papers I've found give closed form equations for the impedance, whether they will work for this remains to be seen. I'll build a single-loop DE version first and see how it performs.

73

Chris G3WIE





Re: 23cm JVL quadloop with log periodic feed

Chris G3WIE
 

Thanks Kent,

Some checking of numbers between the two versions says that, for a given design frequency,  I can build the directors on one section of boom and plug-in a short extra section with either the narrow-band single DE or the log periodic. 

My question about impedance related to the feedline for the 3-loop log periodic section rather than the antenna as a whole. I haven't found any detail of that beyond a sketch, and the calculated dimensions for the spacing of the 3 loops and the length of the s/c stub at the end. Some papers I've found give closed form equations for the impedance, whether they will work for this remains to be seen. I'll build a single-loop DE version first and see how it performs.

73

Chris G3WIE



Re: Attenuators again

i2NDT
 

Hi Alan,
is it possible to have a copy of that Scatterpoint article?

best 73
de
i2NDT Claudio


Chipbank at Finningley

Michael Scott
 

Hi All
 
I plan to be at Finningley R/T on both days this weekend and will have the full stock of the Chipbank with me, so please look at the catalogue on the UKuG website and come with your ‘wants’ lists.
 
See you there!
 
73, Mike, G3LYP.


Re: 23cm JVL quadloop with log periodic feed

KENT BRITAIN
 

Bandwidth is virtually all determined by the directors.
The Driven Element has little to do with bandwidth on long Yagi's.
The LP feed was popular in the 70's and early 80's, but rarely used
today.

All of JVL's antennas designed to be driven with coax are 50 Ohm feed.
I am not aware of any 72 Ohm designs.   I do personally own one of
his 24 GHz slot designs that is 200 Ohm feed line.   (WG20 waveguide!)

Kent G8EMY/W5


From: "g3wie@... [ukmicrowaves]"
To: ukmicrowaves@...
Sent: Tuesday, July 3, 2018 10:06 AM
Subject: [ukmicrowaves] 23cm JVL quadloop with log periodic feed

 
I'm setting out to build a 23cm quad loop, or probably two bayed in the interest of balance on my small Clark mast. Reviewing the available literature (internet, Microwave Handbook 1 P4.7 et seq, G3JVL website/calculator program), I plan to build with the log periodic feed as recommended by G3JVL. My interest initially is SSB/CW and a stab at aircraft scatter. If G8GKQ prevails I could be on DATV one day. I'd appreciate help with some related questions:

To meet my eventual requirement, the band plan implies I'll need coverage from 1242MHz to 1325MHz

- what usable bandwidth does the LP feed provide? I'd be delighted if it will work over that range
- what design frequency should I use? I guess I could veer towards the LF end as that's where  transmitting happens
- what impedance should I choose for the LP feedline?

73

Chris G3WIE



23cm JVL quadloop with log periodic feed

Chris G3WIE
 

I'm setting out to build a 23cm quad loop, or probably two bayed in the interest of balance on my small Clark mast. Reviewing the available literature (internet, Microwave Handbook 1 P4.7 et seq, G3JVL website/calculator program), I plan to build with the log periodic feed as recommended by G3JVL. My interest initially is SSB/CW and a stab at aircraft scatter. If G8GKQ prevails I could be on DATV one day. I'd appreciate help with some related questions:

To meet my eventual requirement, the band plan implies I'll need coverage from 1242MHz to 1325MHz

- what usable bandwidth does the LP feed provide? I'd be delighted if it will work over that range
- what design frequency should I use? I guess I could veer towards the LF end as that's where  transmitting happens
- what impedance should I choose for the LP feedline?

73

Chris G3WIE


Re: Attenuators again

Barry Chambers
 

Hi Alan

many thanks but I can't download the file from the Groups web site since I refuse to accept ads. Please can you send me a copy directly?

73

Barry, G8AGN
On 03/07/2018 11:37, 'Alan Melia' Alan.Melia@... [ukmicrowaves] wrote:

Hi Barry I found the file that generated the Scatterpoint article. I have
up-loaded it to an attenuator check folder on the Yahoo Groups web-site.
It's useful for quickly checking those odd attenuators on rally stands for
burnt out sections (if you carry a cheap DMM ) :-))

It looks as though I may not have put it there previously but rather on my
own web site.

Alan
G3NYK



Re: DB6NT MKU 10 G4

Adrian whatmore <g4uvz@...>
 

With any luck it will just be the tantalum caps and maybe the regulator...as the fuses blew then there shouldn't be any downstream damage!
Adrian


On Wednesday, 27 June 2018, 22:45, "David Warr g4rqi@... [ukmicrowaves]" wrote:


 
Hello...

My DB6NT MKU 10 G4 blew an external +12v DC fuse last night (two to be
exact)... I was wondering if one of the regulators has gone short
circuit. Has anyone had any problems like this with the DB6NT MKU 10 G4?

73 David




Attenuators again

Alan Melia
 

Hi Barry I found the file that generated the Scatterpoint article. I have up-loaded it to an attenuator check folder on the Yahoo Groups web-site. It's useful for quickly checking those odd attenuators on rally stands for burnt out sections (if you carry a cheap DMM ) :-))

It looks as though I may not have put it there previously but rather on my own web site.

Alan
G3NYK


New file uploaded to ukmicrowaves

ukmicrowaves@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ukmicrowaves
group.

File : /Attenuator chack/Attenor.xls
Uploaded by : g3nyk <Alan.Melia@...>
Description : DMM check for attenuator

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ukmicrowaves/files/Attenuator%20chack/Attenor.xls

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

g3nyk <Alan.Melia@...>


Looking for a GR 1236

John Lambo
 

Hello All.
I am looking for a GR1236 for a very good old frind off my.
I do have one here but he want to have one at his home aslo .
If you have one and do not use  and want to sell it for a amatreur price please sent me a mail and make my frind happy.
Thank you for reply .....


73  John  PA7JB


Info about a noise source

John Lambo
 

Hello All.
i do have here a noise source made by English Electric Valve CO LTD   Type  BS758
It is a noise source with WR28 output and smc for the voltage
It must give 25db ERN on 35ghz and i hope to see some noise on 47ghz.
But i do dnot have any info about the input voltage.
Must it be 15 volt or 28volt ??
Does any one know more and can help me with this.
Thank you for reply ....


73  John  PA7JB


Re: DB6NT MKU 10 G4

David Warr <g4rqi@...>
 

Hello...

I didn't get many replies to my original post so I guess this may not have happened to anyone else. I got my 3cm G4 transverter on the bench this morning. The input decoupling capacitor to the 78M05 is totally destroyed and there is some heat damage to the output decoupling capacitors. I am hoping that is it. My transverter is bolted down to a 5mm thick aluminium plate but maybe outside in the current heat in a plastic box this wasn't enough.

73 David - G4RQI

On 27/06/2018 22:44, David Warr wrote:
Hello...

My DB6NT MKU 10 G4 blew an external +12v DC fuse last night (two to be exact)... I was wondering if one of the regulators has gone short circuit. Has anyone had any problems like this with the DB6NT MKU 10 G4?

73 David