Date   

Re: 3.4GHz dish

Andy G4JNT
 

The unofficial archive of PW has it.
John said 1984, and it only took the second download to find - in the  Feb issue




On Wed, 24 Feb 2021 at 08:33, Andy GD1MIP <gd1mip@...> wrote:
John,

Do you have the ability to scan that article?  I'd like to read it.

Thanks Andy GD1MIP 


Re: 3.4GHz dish

Andy GD1MIP
 

John,

Do you have the ability to scan that article?  I'd like to read it.

Thanks Andy GD1MIP 


Re: SHF UKAC

Neil Smith G4DBN
 

It was pretty scary here, even with some extra guying and with the dish at 20ft.  Still, four stations over 200km with the dish just peeping over the barn roof is not too shabby.  The storm south of Sheffield was blowing directly along the path from Peter G3PHO to me, and as he has to beam 180 away to get a reflection, he was actually reflecting off the scatter point, with the hydrometeors moving very fast towards both of us. I nearly missed his reply as the CW was shifted way outside my passband and spread over 1kHz wide. As Peter is on the other side of a 500ft hill from here, the rain must have been between him and the usual reflection point, which we have still not identified, as there was no simple reflection at all, just the RS.

Started very late and gave up early. Nine contacts. Nice to make it with Martyn G3UKV on gravelly SSB via the same storm as with Peter.

Neil G4DBN

On 23/02/2021 23:31, Robin Szemeti - G1YFG wrote:
Far, FAR too windy to put the tower up.  I am a bit exhausted after a stupidly busy work week last week ... my head wasn't in it anyway.


Re: SHF UKAC

Robin Szemeti - G1YFG
 

Far, FAR too windy to put the tower up.  I am a bit exhausted after a stupidly busy work week last week ... my head wasn't in it anyway.


On Tue, 23 Feb 2021 at 18:13, Dave (G1OGY) <g1ogy@...> wrote:
I'll look forward to it Nigel. 
My earlier problem is solved. 
I'll be QRV from 2000hrs.

On Tue, 23 Feb 2021, 17:44 Nigel G8IFN, <nigel@...> wrote:
I will be on 9cm.
Will only be able to work the two stations closest to me, Dave G1OGY and John G4ZTR, as my antenna is still indoors.
--
Nigel G8IFN - JO01LS


--
Robin Szemeti - G1YFG


Re: wtKST

Dave (G1OGY)
 

OK for me all night (since abt 17:15 hrs)

Dave, G1OGY


On Tue, 23 Feb 2021 at 22:35, John Lemay <john@...> wrote:
Anyone else having trouble with wtKST tonight?  It no longer connects me.
I've changed nothing so I'm lost !

John G4ZTR



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wtKST

John Lemay
 

Anyone else having trouble with wtKST tonight? It no longer connects me.
I've changed nothing so I'm lost !

John G4ZTR



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Re: SHF UKAC

Dave (G1OGY)
 

I'll look forward to it Nigel. 
My earlier problem is solved. 
I'll be QRV from 2000hrs.

On Tue, 23 Feb 2021, 17:44 Nigel G8IFN, <nigel@...> wrote:
I will be on 9cm.
Will only be able to work the two stations closest to me, Dave G1OGY and John G4ZTR, as my antenna is still indoors.
--
Nigel G8IFN - JO01LS


Re: SHF UKAC

Nigel G8IFN
 

I will be on 9cm.
Will only be able to work the two stations closest to me, Dave G1OGY and John G4ZTR, as my antenna is still indoors.
--
Nigel G8IFN - JO01LS


3.4GHz dish

John Fell
 

The item twanged a memory location , which turned out to be from 1984 .
The gezzer in the pic is Moi and the article is one I knocked out in my capacity as Tech ED , adding to the original design notes from John G4BVY .
That dish is still at G4RFR and was last used some several years ago when Paul M0EYT and I did a fixed uwave contest from the club site at 30m asl in IO90 .With 100W of old rubbish up the feeder we worked a few OTH F stations .
IO built a VE4MA with the flange fixed but the guide adjustable ( bake beans tin variable length ) tweak in situ for best return loss .Mostly 1/2" galv mesh wired on .

73 
John
G0API 


Re: Supporting the dish feed

John Lemay
 

All

 

Many thanks for the helpful and constructive comments. I think it’s quite likely I’ll make a permanent version of this trial single arm – seems there are more pros than cons.

 

To put some meat on the design; it’s a 1.5m dish with 0.43 F/D. It may not look like that in the picture though. It’s a loop feed with choke, currently with just a 9cms loop, but with 13 and 23cms to be added, based on a design by OM6AA. I’m experimenting with the feed position on 9cms, being the most critical.

 

Bending the ribs is fun, with nothing but a bench vice and a template. The first one took ages but by the time I’d done 11 the last one was just a few minutes work.

 

John G4ZTR

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of David Law
Sent: 23 February 2021 14:38
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Supporting the dish feed

 

I have a similar home made feed without the ring (I think it's a loop you have there). It's supported on a 12mm fibreglass rod running from centre of dish to centre of feed. The feed has 4 thin 100lb non stretch braided Dacron fishing lines running as "guys" to the edge of the dish.
Dacron is used for kite line and fishing line. It could be a solution if to feel the arm is a bit wobbly.


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Re: SHF UKAC

Neil Smith G4DBN
 

Same here, wind is serious at the moment, 40 MPH gusts, and it doesn't look likely to drop much this evening. If I'm on, I'll log into KST.

Neil G4DBN

3cm only IO93NR


On 23/02/2021 13:19, militaryoperator via groups.io wrote:


3Cm if wind drops.

Ben G4BXD IO82UJ


Re: SHF UKAC

Dave (G1OGY)
 

If I can get the 9cm kit out of uncommanded TX, I'll be on 3400, only.


On Tue, 23 Feb 2021, 13:14 G1DFL via groups.io, <peterdwberkshire=yahoo.com@groups.io> wrote:
I plan to be on 13cm and 9cm tonight for the Feb SHF UKAC, wind permitting!
Hope to work a few of you, especially if local to IO91.

Anyone else on?

Regards...Pete
G1DFL


Re: SHF UKAC

Robin Szemeti - G1YFG
 

13cm with new preamp, iff the wind drops ...


On Tue, 23 Feb 2021 at 13:19, militaryoperator via groups.io <Military1944=aol.com@groups.io> wrote:


3Cm if wind drops.

Ben G4BXD IO82UJ



-----Original Message-----
From: G1DFL via groups.io <peterdwberkshire=yahoo.com@groups.io>
To: UK Microwaves groups.io <ukmicrowaves@groups.io>
Sent: Tue, 23 Feb 2021 13:13
Subject: [UKMicrowaves] SHF UKAC

I plan to be on 13cm and 9cm tonight for the Feb SHF UKAC, wind permitting!
Hope to work a few of you, especially if local to IO91.

Anyone else on?

Regards...Pete
G1DFL


--
Robin Szemeti - G1YFG


Re: Supporting the dish feed

David Law
 

I have a similar home made feed without the ring (I think it's a loop you have there). It's supported on a 12mm fibreglass rod running from centre of dish to centre of feed. The feed has 4 thin 100lb non stretch braided Dacron fishing lines running as "guys" to the edge of the dish.
Dacron is used for kite line and fishing line. It could be a solution if to feel the arm is a bit wobbly.


Re: SHF UKAC

militaryoperator
 



3Cm if wind drops.

Ben G4BXD IO82UJ



-----Original Message-----
From: G1DFL via groups.io <peterdwberkshire@...>
To: UK Microwaves groups.io <ukmicrowaves@groups.io>
Sent: Tue, 23 Feb 2021 13:13
Subject: [UKMicrowaves] SHF UKAC

I plan to be on 13cm and 9cm tonight for the Feb SHF UKAC, wind permitting!
Hope to work a few of you, especially if local to IO91.

Anyone else on?

Regards...Pete
G1DFL


SHF UKAC

G1DFL
 

I plan to be on 13cm and 9cm tonight for the Feb SHF UKAC, wind permitting!
Hope to work a few of you, especially if local to IO91.

Anyone else on?

Regards...Pete
G1DFL


ANDREWS LDF CONNECTORS

Adrian G4UVZ
 

L5PDF x 3 and BN7331 07 x 1 
 L5PDF to SO239 adaptor

Free to a good home


Re: Supporting the dish feed

Mike Willis
 

The metalwork right next to the feed may act as a reflector reducing gain and generating sidelobes. Whether this will be better or worse than the traditional feed is something you would been to simulate. The Shepheard's crook feed has been popular for a long time. Can't be that bad.
--
Mike G0MJW


Re: Supporting the dish feed

John Fell
 

Hi John,
For your example of just the feedhorn to support on the single arm it has the advantages of minimal aperture shadowing and reduced feeder run .

For feed mounted RF systems a tri-or quad allows reduced individual section arms and a closed system of forces , which will improve rigidity and resistance to windage loadings , without undue increased blockage.

Looking at the tower head I guess the dish is around 6Ft diameter and middle range F/d - using at 2.3GHz or 3.4GHz  ? 

73
John
G0API

On Tue, 23 Feb 2021 at 09:24, John Lemay <john@...> wrote:
Morning all

Supporting a dish feed - one arm, three or four ??

I've recently completed a new prime focus mesh dish. I made up the usual
four arms to make a quadruped to support the feed from the rim. But it
looked a bit tricky to adjust the feed position so temporarily I provided
instead a single support close to the axis of the dish. A simple series of
holes on this arm gave me easy options for moving the feed to and fro.

I made a small hole in the mesh next to the hub to pass the cable through.
That makes it obvious that the feed cable can be shorter than one which
follows one of four arms to the rim.

I'm happy with the mechanical side of things (such as the single arm needs
to be stiffer), but what are the pros and cons as far as RF performance is
concerned ?

TIA

John G4ZTR



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Re: Supporting the dish feed

Denis Stanton G0OLX
 

John
Thank looks like a very good solution with minimal metal in the way of incoming rf.
Best 73’s
Denis
G0OLX

On 23 Feb 2021, at 09:24, John Lemay <john@carltonhouse.eclipse.co.uk> wrote:

Morning all

Supporting a dish feed - one arm, three or four ??

I've recently completed a new prime focus mesh dish. I made up the usual
four arms to make a quadruped to support the feed from the rim. But it
looked a bit tricky to adjust the feed position so temporarily I provided
instead a single support close to the axis of the dish. A simple series of
holes on this arm gave me easy options for moving the feed to and fro.

I made a small hole in the mesh next to the hub to pass the cable through.
That makes it obvious that the feed cable can be shorter than one which
follows one of four arms to the rim.

I'm happy with the mechanical side of things (such as the single arm needs
to be stiffer), but what are the pros and cons as far as RF performance is
concerned ?

TIA

John G4ZTR



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