Date   

Re: Buying from the EU

Robert G8RPI
 

Robin  G1YFG said:
"We always advise customers to avoid mentioning anything to do with repair and simply put a value of £50 on it. It's cheaper to pay the (small) amount of VAT and a simple handling fee than the  handling fees on the "repair" customs procedure which are usually around £70."
This is actually illegal and could be considered fraud. Apart from that, if an item goes astray or is damaged the insurance company is unlikely to pay more than the declared customs value. I assume this is EMC test equipment that costs a lot more than £50.

Robert G8RPI.


Re: G3WDG Filters for 2 mtr to 10GHz receiver

Steve G4HTZ
 

I have ..amazingly found the filters and sent Dennis a picture to check it’s what he needs 
if not someone else may want them 


--
Steve G4HTZ 
JO01JN60
Great Wakering, Essex 
24ghz 1.8w 80cm dish 

also known to be active occasionally on 70cms DATV 


Re: KST2ME demise

Phil Guttridge G3TCU
 

Your 'web thing' looks very promising Robin, thanks for the effort on that. I like the Chat1/Chat2 approach in KST2me, i.e. all messages and filtered messages. I guess that can also be done with two browser tabs. Another thing that sometimes comes in useful is the 'save chat' (to text file)  so you can later read something that was scrolling by too quickly to catch at the time (or you caught the tail end of, as your attention was elsewhere).

73, Phil G3TCU



On 17/01/2022 11:00, Robin Szemeti - G1YFG via groups.io wrote:
As some of you may have heard, the author of KST2ME, Bo, has said that no more license keys will be issued,  once your current key expires, it is dead.

If anyone has any specific features of KST2ME that they would dearly love to have included in my web-based alternative, if you could let me know by PM, ideally with a screenshot,  I'll try and at least consider them.

There is a write-up of my web thing here, if anyone is unfamiliar.


--
Best regards,

Robin Szemeti, G1YFG

--
Robin Szemeti - G1YFG


Re: KST2ME demise

Robin Szemeti - G1YFG
 

Hi David, not currently.  You could of course open two "tabs" in your browser, one for each band.

Others have mentioned the "two bands" thing,  I'll consider it, I am keen to keep the display simple and uncluttered though, feature creep is a killer ... in the meantime, don't forget you can always open a second browser and just use your Windows features to display two (or more) on the screen, ...




On Tue, 18 Jan 2022 at 17:47, David Hilton-Jones via groups.io <g4ytl=aol.com@groups.io> wrote:

Many thanks Robin

 

Very useful

 

I may be being stupid, but is there any way of changing bands displayed without logging out and back in?

 

One useful feature in KST2ME was being able to display two bands simultaneously.

 

73

 

David, G4YTL

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Robin Szemeti - G1YFG via groups.io
Sent: 17 January 2022 11:00
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] KST2ME demise

 

As some of you may have heard, the author of KST2ME, Bo, has said that no more license keys will be issued,  once your current key expires, it is dead.

 

If anyone has any specific features of KST2ME that they would dearly love to have included in my web-based alternative, if you could let me know by PM, ideally with a screenshot,  I'll try and at least consider them.

 

There is a write-up of my web thing here, if anyone is unfamiliar.

 


--

Best regards,

Robin Szemeti, G1YFG


--
Robin Szemeti - G1YFG


--
Robin Szemeti - G1YFG


Re: 3D printed cassegrain reflector.

Neil Smith G4DBN
 

Ian's mention of gold leaf got me thinking.  Assuming I could find a suitable size or surface treatment that would release easily, I wonder if I could make tiny gold-lined horns by burnishing leaf on to a mandrel, then electroforming copper on to the outside, thickly enough to encase it and make it stiff enough for machining, or at least casting into resin?  If the size or whateve would melt at lowish temps, and dissolve in solvents, it might cut out the painful steps of electroforming onto an aluminium mandrel.  Dropping the "oxide-etch/zincate/nickel plate" steps and the "machine out the mandrel/dissolve in hot caustic" steps would make things a lot easier.  I guess though that the copper would leach through the gold, or that maintaining adhesion of the leaf to the mandrel might not be straightforward. Just think of the bling factor though!

It's marvellous to see all of the work going on with the Cassegrain designs.

A French team are trying out a simple CNC router/mill and getting decent results, and I see that lots of folks are trying 3D printing of various geometries and surface finishes.  I'm sticking to manual machining of a flat template and using a 10mm diameter follower and 10mm diameter tool, to get close to a mirror finish, but that's not much use for anyone without a convenient machine shop and I'm snowed under with the day job and a long backlog of machining work. 

The elephant in the room is how bad the surface accuracy of those deep Edmund dishes is.  I think we are going to hit the limit of the parabola errors soon, with all the machined and printed subreflectors getting good accuracies.  Modelling with a perfect surface shows about 54 dBi according to Michel's simulations. I'm having amusing issues in getting sufficient stiffness and adjustability in the mount to optimise all of the variables.  The subreflector needs to be very precisely positioned so its rear hyperbolic focus coincides with the focus of the parabola, but also its axis needs to coincide with the axist of the parabola.  That might not be at where we think it is, so I'm allowing for lateral positioning, canting and axial positioning adjustment.  The feedpoint position isn't quite as sensitive, as the worst that will happen if the axis of the horn isn't aligned with the axis of the dish/sub combination is just a pointing error. Getting the feed phase centre to coincide with the secdond focus of the hyperbola seems to matter only in the axial direction, so a decent focus slide matters more than sideways positioning. There doesn't seem to be much impact on gain for a lateral error of 6 mm.  Using a very long interfocal distance for the hyperbola should mean that axial positioning of the phase centre of the feed is less critical than if the feed is on a stalk and close to the subreflector.  I just picked "roughly in line with the dish surface" as my chosen feed position so I could make a simple axial focus slide to mount the PCB and horn assembly. I am making a wild assumption that the axis of the Edmund dishes is close to the centre of the hole in the dish.  That might not be true, but I think 5mm either way is proabbly unimportant, and making the subreflector position adjustable will allow that to be compensated for.

I'm using thin carbon fibre rods to support the delrin spider which carries the threaded subreflector. That thread is 0.5 mm pitch, so it's easy to get extremely fine control of the focus.  The support rods are also finely threaded to allow adjustment of the spider position in three orthogonal axes as well as it's axial alignment.

The other aspect of the Cassegrains that I'm worrying about is the edge taper for the feedhorns. If the feed was at the parabola focus, and you want to get an edge taper of around 11dB to balance gain against overspill, then you need to consider that the distance from the horn to the edge of an f/d 0.25 dish is twice that to the centre, so there's an automatic 6dB or so of space attenuation, so the horn would need have a wider pattern than you'd expect, with -5dB at the dish edge to get the illumination at -11dB.  That's a bit theoretical as a feed as wide as that is hard work.  With the Cassegrain, the feedhorn sees a virtual dish that subtends a half-angle ( in this case) of about arctan(24/105) or around 13 degrees. In this geometry, the distance to the edge of the dish is about 1.5 times the distance to the centre, so the space attenuation is rather lower. That leads to a feedhorn with a taper that's about -9dB at +- 13 degrees being roughly right for the job.  I'm expecting there are a lot of confounding variables though, so my plan is to make a range of different dual-mode horns of various gains to see where the sweet spot is.  W2IMUs get a bit unweidly at those gains, so I'm working on the assumption that a Pickett-Potter will be a decent choice.  Simple horns have some nasty sidelobes and aren't really any easier to machine.

All of this mucking about is unlikely to result in something that's much better than you could do with a card template and a lump of something spinning in an electric drill held in a vice and filed to shape, then coated with burnished foil, but I'm interested in that extra 1dB that means an extra kilometer, or those few extra dB that gets me further still. The important and interesting bit of ham radio for me isn't the end result, it's all the buggering about that you have to do to reach that point.

My next step for later in the year is using this Prusa 3D printer to make a honeycomb-back mould pattern for a dish around 13 inches diameter, then casting it in aluminium. The outline plan is to make a super stiff but light axially-displaced ellipse antenna, with an inside-out Gregorian feed and no subreflector blockage. I'll mill the back flat, then mount it on a big cast-iron faceplate on my lathe to turn the reflector surface. It will need sufficient stiffness and precision so it will work OK from 47 GHz up to > 275 GHz.  I'll need to heat-treat it, or find someone with liquid nitrogen to make sure it's suitably stress-relieved and doesn't relax and bend as it ages.  Then I need to think about surface finishes that will work OK.  I guess anodising will be OK at mmwave frequencies, and it would look rather spiffy with an electric-blue dyed surface, but I'll have to find out. Yet more buggering about. Huzzah!

Some days I wonder if I should just give in and string up an EFHW and 81:1 unununun and play on those funny HF bands?  Nah, where's the fun in that?

If anyone's interested, I just published a new video on my Youtube channel about how I machine the coupler bodies for the various antenna types on the VK3CV boards.

It contains Humour, because there isn't enough of that in the world these days.

https://www.youtube.com/watch?v=uAG7y3tl9s8

I'll publish updates on my Cassegrain experiments and feedhorn works soon, but the day job is intruding into life again. On my day off too.


Re: KST2ME demise

David Hilton-Jones
 

Many thanks Robin

 

Very useful

 

I may be being stupid, but is there any way of changing bands displayed without logging out and back in?

 

One useful feature in KST2ME was being able to display two bands simultaneously.

 

73

 

David, G4YTL

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Robin Szemeti - G1YFG via groups.io
Sent: 17 January 2022 11:00
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] KST2ME demise

 

As some of you may have heard, the author of KST2ME, Bo, has said that no more license keys will be issued,  once your current key expires, it is dead.

 

If anyone has any specific features of KST2ME that they would dearly love to have included in my web-based alternative, if you could let me know by PM, ideally with a screenshot,  I'll try and at least consider them.

 

There is a write-up of my web thing here, if anyone is unfamiliar.

 


--

Best regards,

Robin Szemeti, G1YFG


--
Robin Szemeti - G1YFG


Re: 3D printed cassegrain reflector.

Peter G3SMT
 

How about using silver leaf ?

Peter  G3SMT


On 18/01/2022 16:20, Paul G8AQA via groups.io wrote:
Aluminium foil will have a higher conductivity than gold and may be able to be stretched over the plastic. Kitchen foil shiny side out may do the job.

Paul G8AQA

On 18/01/2022 10:58, Mike Willis wrote:
Another gold plated project?
--
Mike G0MJW


Virus-free. www.avg.com

--
Peter G3SMT


Re: 3D printed cassegrain reflector.

Paul G8AQA
 

Aluminium foil will have a higher conductivity than gold and may be able to be stretched over the plastic. Kitchen foil shiny side out may do the job.

Paul G8AQA

On 18/01/2022 10:58, Mike Willis wrote:
Another gold plated project?
--
Mike G0MJW


Virus-free. www.avg.com


Re: UK Microwave Group Contests in 2022

Pete - GM4BYF
 

Happy with the 76+ GHz arrangements. It makes sense to me.

73
Pete GM4BYF

On 16/01/22 21:26, John Quarmby via groups.io wrote:
I have not had much feedback on the UKuG contest programme, apart from on events on 76GHz and above.

The present arrangement of fixed dates for these mm-wave contests is not conducive to pushing the boundaries of propagation on these bands, as the weather is often uncooperative with rain/wind or very high humidity.

A group of those active on these bands has suggested that a more flexible approach would be welcome. It is therefore proposed that groups set up their own activity days, not more than three between January and June, and not more than three from July to December, with each activity day separated from previous or subsequent events by at least two weeks. Different groups can set their activity periods independently, there is no requirement for UK wide coordination.

Contacts on activity days would require passing 8 character locators, signal reports and serial numbers. Results from each 6 month period will be published in Scatterpoint.

I am about to finalise the rules for next year and would welcome comments on this change before I put them to bed.

73

John G3XDY
UKuG Contest Manager

--
vry 73
Pete GM4BYF


Re: GHz Bands column input requested

Michael Scott
 

Yes, those parts used in G4EML's converter are still available!

73, Mike, G3LYP

On 17/01/2022 19:50, Andy G4JNT wrote:
I think there are mixers in the chipbank that go to 2GHz+
In fact...
IIRC...
There was a 2.4GHz upconverter design doing the rounds a couple of years ago based on chipbank components.
So could probably be turned into an Rx one way or another.



On Mon, 17 Jan 2022 at 19:40, Andrew M0CWX <ajm143@...> wrote:
How about a minimal working example receiver for 2.3GHz? Getting me an RX (of sorts) on 13 cms. 

Using cheap ADF4351 for LO on 1888 MHz;
homemade (yes that’s tinfoil and garden wire!) bi-quad;
mixer I got as junk at the Roundtable and 
an SDR dongle.

Not going to win a DX award but on the waterfall is GB3ZME 25 miles away from the antenna on the bench.

Best wishes,
Andrew
M0CWX
Halesowen
IO82XK







Re: GHz Bands column input requested

Colin Ranson
 

Sam,    A one day event would be nice.

 

Good to see you  and your good lady the other day.

 

Best regards

 

 

Colin de G8LBS

 

 

Sent from Mail for Windows

 

From: SAM JEWELL via groups.io
Sent: 17 January 2022 11:16
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] GHz Bands column input requested

 

The Martlesham Organisers are looking at a possible one day event for 2022. Details will be announced when firmer arrangements have been made.

Hope to see lots of you there.

 

Sam, G4DDK



On 17 Jan 2022, at 10:42, David Hilton-Jones via groups.io <g4ytl@...> wrote:



Hi John

 

A fallow time of year!

 

Making progress on 3cm EME – now 21# and 13 DXCC

 

Slowly building a system for 3cm tropo/rain scatter from home – will be a 60cm dish and 3 watts output. Hope to be QRV by February.

 

Managed to find a power meter and sensor head at reasonable price – HP437B and HP8481A head (-30dbm to 20dbm)

 

Do you know if Martlesham will go ahead this year?

 

 

Unrelated to column, I will send you an email I recently received from PA3DZL – might be of interest.

 

73

 

 

David, G4YTL

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of g4bao
Sent: 16 January 2022 18:57
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] GHz Bands column input requested

 

Hi All

Its that time of year when it's hard to find much interesting going on that makes good column inches, so I'd appreciate any news or Tech Snippets etc by Wednesday at the latest please.

Otherwise It'll be another "Fen Edge Soapbox" and we don't want that, do we? ! :-)  

Someone must have done something remarkable, but I have to admit I haven't .....

:-)

73

John

 


Re: 3D printed cassegrain reflector.

Mike Willis
 

Another gold plated project?
--
Mike G0MJW


Re: 3D printed cassegrain reflector.

Colin G4EML
 

It would be worth a try. I don’t know anything about using gold leaf, does it bond together well to give 100% coverage?

Colin G4EML



On 18 Jan 2022, at 09:00, Ian White <gm3sek@...> wrote:

After sanding down the PLA, would there be any objection to burnishing directly with gold leaf?

Skin depth in gold at 122GHz is about 0.2um, which is very similar to the thickness of gold leaf so it might be necessary to build up a few layers - but the subreflector itself is only 48mm OD and gold leaf isn't all that expensive. The process would certainly be more sanitary than any of the wet chemistry methods being proposed.

73 from Ian GM3SEK


Re: 3D printed cassegrain reflector.

Ian White
 

After sanding down the PLA, would there be any objection to burnishing directly with gold leaf?

Skin depth in gold at 122GHz is about 0.2um, which is very similar to the thickness of gold leaf so it might be necessary to build up a few layers - but the subreflector itself is only 48mm OD and gold leaf isn't all that expensive. The process would certainly be more sanitary than any of the wet chemistry methods being proposed.

73 from Ian GM3SEK


Re: G3WDG Filters for 2 mtr to 10GHz receiver

Dennis_G6YBC
 

Thanks Andy 

I’ve downloaded the respective file, now to look at the build. 

Regards 

Dennis G6YBC 




Re: 3D printed cassegrain reflector.

Colin G4EML
 

The dish is about 110mm deep and the horn protrudes 5mm onto that. So the distance from horn to reflector is about 105mm. 

Colin. 


Re: GHz Bands column input requested

VK5OI John
 

Great stuff Andrew, that's what it's all about, in my opinion.
Messing around with a mixer, cheap PLL LO and in my case an FT-817 for the IF was the "lightbulb" moment when I realised working on the uwave bands was doable for me.
As you probably know, the mixer will also work (to some degree) as a subharmonic mixer so the LO could be 3312MHz (432MHz IF) for 10GHz, or any of the bands in between, but out of fundamental reach of the ADF4351.

thanks for sharing
John VK5OI

On Tue, Jan 18, 2022 at 6:10 AM Andrew M0CWX <ajm143@...> wrote:
How about a minimal working example receiver for 2.3GHz? Getting me an RX (of sorts) on 13 cms. 

Using cheap ADF4351 for LO on 1888 MHz;
homemade (yes that’s tinfoil and garden wire!) bi-quad;
mixer I got as junk at the Roundtable and 
an SDR dongle.

Not going to win a DX award but on the waterfall is GB3ZME 25 miles away from the antenna on the bench.

Best wishes,
Andrew
M0CWX
Halesowen
IO82XK







Re: GHz Bands column input requested

John Worsnop
 

I think Scatterpoint will be interested in the details of that!
Not really room for full tech articles in my 2 page column. Send it to editor@... and I'll rreference it in the column when it is published!

73
John


On Mon, 17 Jan 2022 at 19:40, Andrew M0CWX <ajm143@...> wrote:
How about a minimal working example receiver for 2.3GHz? Getting me an RX (of sorts) on 13 cms. 

Using cheap ADF4351 for LO on 1888 MHz;
homemade (yes that’s tinfoil and garden wire!) bi-quad;
mixer I got as junk at the Roundtable and 
an SDR dongle.

Not going to win a DX award but on the waterfall is GB3ZME 25 miles away from the antenna on the bench.

Best wishes,
Andrew
M0CWX
Halesowen
IO82XK







Re: 3D printed cassegrain reflector.

eightyelectric
 

Nice work, what was the pproximate optimum distance from the brass feed, to the reflector? 


Paul G6UAJ


-------- Original message --------
From: Colin G4EML <colin@...>
Date: 17/01/2022 17:31 (GMT+00:00)
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 3D printed cassegrain reflector.

With todays slightly warmer weather I have been doing some initial tests outdoors with the 3d printed and copper plated cassegrain reflector and 18" Edmund dish on 122GHz. 
The results look very encouraging. Adjustment of the reflector shows a well defined peak in gain when the tip of the reflector is in line with the face of the dish. Which I think is what was intended in Neil's calculations. 
Adjustment of the feed horn does not seem to be anywhere near as critical, I have ended up with it protruding from the rear of the dish by about 5mm. 

This is giving me a Very sharp beam with only one well defined peak.  

My test source is just an RF Explorer signal generator at 4.9Ghz feeding about +10dBm into a diode soldered across the end of a short piece of semi rigid to generate the 25th Harmonic. I can detect this at about 20dB over the noise level a range of 10m.  I will try to do some comparison tests with other antennas later in the week if the weather stays OK. 

Colin G4EML





Re: GHz Bands column input requested

Andy G4JNT
 

I think there are mixers in the chipbank that go to 2GHz+
In fact...
IIRC...
There was a 2.4GHz upconverter design doing the rounds a couple of years ago based on chipbank components.
So could probably be turned into an Rx one way or another.



On Mon, 17 Jan 2022 at 19:40, Andrew M0CWX <ajm143@...> wrote:
How about a minimal working example receiver for 2.3GHz? Getting me an RX (of sorts) on 13 cms. 

Using cheap ADF4351 for LO on 1888 MHz;
homemade (yes that’s tinfoil and garden wire!) bi-quad;
mixer I got as junk at the Roundtable and 
an SDR dongle.

Not going to win a DX award but on the waterfall is GB3ZME 25 miles away from the antenna on the bench.

Best wishes,
Andrew
M0CWX
Halesowen
IO82XK






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