Date   

Re: Wavelab 2W 24Ghz TRV

Steve G4KNZ
 

I agree, these boards from Pawel SP1GQC look excellent, I just need to know how I can order a set?


Re: Wavelab 2W 24Ghz TRV

Neil Smith G4DBN
 

Those boards are an excellent solution Staszek.

73 Neil

On 11/03/2021 16:20, Stanislaw Ziemczonek wrote:
 Steve  ,
I use it:
https://www.tme.eu/pl/details/20021111-00020t4lf/listwy-i-gniazda-kolkowe/amphenol/
I will probably order a PCB suitable for each 2x10 pin socket, whose design was made by Pawel SP1GQC,
as in the attachment to the e-mail.
73's de Staszek SP6GWB
I ordered one, which arrived today (just arrived, no fee or VAT to pay at least so far).
The PCB connectors appear to be 20-way (2x10way) 1.27mm pitch female, does anyone happen to know the correct or an appropriate part to mate with these?

Steve G4KNZ

-- 
Neil
http://g4dbn.uk


Re: Wavelab 2W 24Ghz TRV

Stanislaw Ziemczonek
 

 Steve  ,
I use it:
https://www.tme.eu/pl/details/20021111-00020t4lf/listwy-i-gniazda-kolkowe/amphenol/
I will probably order a PCB suitable for each 2x10 pin socket, whose design was made by Pawel SP1GQC,
as in the attachment to the e-mail.
73's de Staszek SP6GWB

I ordered one, which arrived today (just arrived, no fee or VAT to pay at least so far).
The PCB connectors appear to be 20-way (2x10way) 1.27mm pitch female, does anyone happen to know the correct or an appropriate part to mate with these?

Steve G4KNZ


Re: Dish for 10GHz.

Neil Smith G4DBN
 

Satgear.co.uk do a 40cm dish, you get an LNB with it, not sure if you can get the dish alone. Gibertini 60cm dishes from Hisat are always good. Illuminating a Sky oval 60 x 45 dish isn't quite as easy a normal offset, but they are very cheap. 40cm is going to get you around 30 dBi, a 60cm around 34 dBi. A smaller dish that you can use when it is windy is going to outperform a big one that you can't get up in the clear.

My 95cm dish is scary at 13 metres on a breezy day, but probably gets me 37 dBi.

40cm is getting close to the lower limit at 10 GHz, but diffraction losses won't be noticeable at that diameter.

Neil G4DBN

On 11/03/2021 14:48, Colin Ranson wrote:

Now that the 3cm transverters will soon be available, and many thanks to Neil for his hard work, I guess we will all have to start thinking antennas. Some of us will no doubt already be there, but I have to start thinking of options.  I intend to start small, with a 125mW amplifier/LNA/relays in a plastic box under the feed horn support arm with the transverter in the loft/shack.  And also by small I mean the dish – how rare are 40cm round offset dishes it seems ? and how much gain can I expect from a 40cm dish alone ? The ones I’ve seen are hugely expensive.  The feed is still under consideration as is a standard Zone one elliptical. I really need to keep it small as there is already a Sky dish on the building as well as a QO-100 1m dish round the other side. I am hoping it will share a bit of space under my 9cm QLY.

 

Thoughts appreciated please.

 

73’s and thanks

 

Colin de G8LBS.

 



Dish for 10GHz.

Colin Ranson
 

Now that the 3cm transverters will soon be available, and many thanks to Neil for his hard work, I guess we will all have to start thinking antennas. Some of us will no doubt already be there, but I have to start thinking of options.  I intend to start small, with a 125mW amplifier/LNA/relays in a plastic box under the feed horn support arm with the transverter in the loft/shack.  And also by small I mean the dish – how rare are 40cm round offset dishes it seems ? and how much gain can I expect from a 40cm dish alone ? The ones I’ve seen are hugely expensive.  The feed is still under consideration as is a standard Zone one elliptical. I really need to keep it small as there is already a Sky dish on the building as well as a QO-100 1m dish round the other side. I am hoping it will share a bit of space under my 9cm QLY.

 

Thoughts appreciated please.

 

73’s and thanks

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 


Re: Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Neil Smith G4DBN
 

Certainly adding a choke ring lets me clean up the sidelobes radically, as does converting the design to a non-lensed Pickett-Potter or W2IMU, but my primary intent was to make a lens horn that can be mounted very close to a 5.6 GHz horn on the same dish, so keeping the outside diameter under 25mm would be good.

I think I've found another paper about characteristic impedance of an unenclosed dielectric guide, although it is densely mathematical, so I need a good night's sleep before reading it. If it makes any sense to me, I'll add a link to it on the UKuG wiki and write a covering page.

Neil

On 11/03/2021 13:22, Mike Willis wrote:
Try a pie tin (aka Chaparral ring) as it will help reduce sidelobes
--


Re: Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Mike Willis
 

Try a pie tin (aka Chaparral ring) as it will help reduce sidelobes 
--
Mike G0MJW


Re: Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Neil Smith G4DBN
 

Simulation is working fine, but I had a feeling there was an analytical solution to calculate the characteristic impedance of a dielectric rod waveguide in air. Intellectual curiosity getting the better of me in late-night modelling sessions....

The extension rod does seem to reduce the sidelobes a little when it is about 6mm diameter.  I'm more interested in getting the edge taper right, and by adjusting the cone angle, I can get a nicely flattened lobe with a slight dip in the middle.  This is  in a 22 mm diameter tube but with a narrower lobe and no dip. It will be amusing to see if the real thing is anything close to the models

Neil G4DBN



Re: Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Mike Willis
 

Simulate it perhaps? E.g. the HB9PZK design lens in 22mm circular waveguide.



 
--
Mike G0MJW


Re: Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Dominique Dehays
 

Hi Matti ,


thx very much for this interesting report , it gives me some ideas...

73

Dom/F6DRO


Re: Wavelab 2W 24Ghz TRV

Neil Smith G4DBN
 

I haven't had mine under the microscope yet. Hope to have a close look for any polarity bumps tomorrow night. I think I have a suitable collet crimper so any individual-wire connector will do. I might look for one that is pre-terminated with pigtails, because laziness...

Neil G4DBN

On 10/03/2021 22:55, Steve G4KNZ wrote:
I ordered one, which arrived today (just arrived, no fee or VAT to pay at least so far).
The PCB connectors appear to be 20-way (2x10way) 1.27mm pitch female, does anyone happen to know the correct or an appropriate part to mate with these?

S


Re: Wavelab 2W 24Ghz TRV

Steve G4KNZ
 

I ordered one, which arrived today (just arrived, no fee or VAT to pay at least so far).
The PCB connectors appear to be 20-way (2x10way) 1.27mm pitch female, does anyone happen to know the correct or an appropriate part to mate with these?

Steve G4KNZ


GB3VHF

ian hope (2E0IJH)
 

Have sent Chris a email and a friend has sent him a text, but if any has contact with Chris FDZ, GB3VHF seems ill, its very low on output and sometimes just keys dead carrier, GB3UHF seems ok
 
There was a Major power outage in Meopham/Vigo with flickering power and overhead line arcing
 
Ian
M5IJH


Re: Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Neil Smith G4DBN
 

Hi Matti! Very interesting document, many thanks.  I need to read it thoroughly, but it is late and I need to sleep.

Neil G4DBN

On 10/03/2021 21:30, Matti Lukkarinen,OH1DB wrote:
HI Neil!

Here you get some information. With this document, i have done my own polyrod antenna
https://hamwaves.com/dielectric.rod/doc/dielectric_rod_antenna.pdf

de. Matti oh1b

On Wed, 10 Mar 2021 at 21:22, Neil Smith G4DBN <neil@...> wrote:

I'm doing some simulations of dielrod/dielspike horns using a simple taper from a round waveguide down to a round rod.  The plan is to set the diameter of the round rod extension such that it has the same impedance as free space, so there is no discontinuity at the end of the taper, and hopefully to minimise reflections.

Can anyone point me at a way to calculate the diameter of a dielectric rod guide to get the impedance of the terminal extension close to 377 ohms?  At the moment, I'm just fiddling with the diameter to see if I can reduce the sidelobes a little, but I'd prefer to set the rod to a known size, then adjust the length of the rod and the taper angle.

The dielectric plastic is Rexolite 1422, with a dielectric "constant"  of 2.53. 

Neil G4DBN

-- 
Neil
http://g4dbn.uk


Re: Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Matti Lukkarinen,OH1DB
 

HI Neil!

Here you get some information. With this document, i have done my own polyrod antenna
https://hamwaves.com/dielectric.rod/doc/dielectric_rod_antenna.pdf

de. Matti oh1b

On Wed, 10 Mar 2021 at 21:22, Neil Smith G4DBN <neil@...> wrote:

I'm doing some simulations of dielrod/dielspike horns using a simple taper from a round waveguide down to a round rod.  The plan is to set the diameter of the round rod extension such that it has the same impedance as free space, so there is no discontinuity at the end of the taper, and hopefully to minimise reflections.

Can anyone point me at a way to calculate the diameter of a dielectric rod guide to get the impedance of the terminal extension close to 377 ohms?  At the moment, I'm just fiddling with the diameter to see if I can reduce the sidelobes a little, but I'd prefer to set the rod to a known size, then adjust the length of the rod and the taper angle.

The dielectric plastic is Rexolite 1422, with a dielectric "constant"  of 2.53. 

Neil G4DBN


Calculating the impedance of a dielectric rod in free space to get a match to 377 ohms?

Neil Smith G4DBN
 

I'm doing some simulations of dielrod/dielspike horns using a simple taper from a round waveguide down to a round rod.  The plan is to set the diameter of the round rod extension such that it has the same impedance as free space, so there is no discontinuity at the end of the taper, and hopefully to minimise reflections.

Can anyone point me at a way to calculate the diameter of a dielectric rod guide to get the impedance of the terminal extension close to 377 ohms?  At the moment, I'm just fiddling with the diameter to see if I can reduce the sidelobes a little, but I'd prefer to set the rod to a known size, then adjust the length of the rod and the taper angle.

The dielectric plastic is Rexolite 1422, with a dielectric "constant"  of 2.53. 

Neil G4DBN


Re: Feedthrough capacitor wanted

G4WIM KT6UK
 

Andy,

I had the same problem when building my 13cm PA - I had the feed thru's but they were an American thread, landed up buying a tap from China to match the thread pitch / size.

Worked out a lot cheaper than buying new metric feed thru's.

73 Tim


Re: New 241 GHz record (via F1VL)

militaryoperator
 


I can usually work into netherlands/france/Jersey with 50W on 70cm from my location, and I have to beam through the hill that you sit on ... I was otherwise occupied on Tuesday, will be on 6m on Thursday though.



Fantastic. 

Best last night here in 432FMAC was just 62Km, with 50W to X5000 colinear at 50ft. 

Mind you, someone got 112Km with 25W and a dipole......... apparently!.
I wonder how high the dipole was?

Seems I'm wasting my time and efforts in some respects. 

Ben G4BXD

--
Robin Szemeti - G1YFG
_._,_._,_


Re: New 241 GHz record (via F1VL)

Neil Smith G4DBN
 

On 10/03/2021 11:22, militaryoperator via groups.io wrote:

Seems I'm wasting my time and efforts in some respects.
Hi Ben, time spent playing on the radio is never wasted though. It is far better than time spent NOT playing on the radio...

I often struggled to make 50 km in the 432 FMAC using an 18-ele beam and my handheld, even with it vertical, so you are doing better than I was.

There is a lot of chat around how the 20 mW at 241 GHz was generated. With 57 dBi gain, that is a mighty EIRP, and then the little matter of climbing a mountain and having an optical path does tend to add a shedload of dBs to the signal!

Nel G4DBN


Re: New 241 GHz record (via F1VL)

Robin Szemeti - G1YFG
 

I can usually work into netherlands/france/Jersey with 50W on 70cm from my location, and I have to beam through the hill that you sit on ... I was otherwise occupied on Tuesday, will be on 6m on Thursday though.

On Wed, 10 Mar 2021 at 11:22, militaryoperator via groups.io <Military1944=aol.com@groups.io> wrote:
New IARU R1 record on 241 GHz. QSO 6 March 2020, 17.10 UTC between:
DK5NJ at JO50TI29JN 690m ASL Schwedenwache (DK0NA) and DB6NT at JO60GJ03MN 896m ASL Aschberg (Saxe).
Distance 63.987 km.
--------------------------------

Fantastic. 

Best last night here in 432FMAC was just 62Km, with 50W to X5000 colinear at 50ft. 

Mind you, someone got 112Km with 25W and a dipole......... apparently!.
I wonder how high the dipole was?

Seems I'm wasting my time and efforts in some respects. 

Ben G4BXD


--
Robin Szemeti - G1YFG

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