Date   

Re: Draft UKUG Contest Calendar/Rules for 2008

Mike Willis <m.j.willis@...>
 

It is good to see some movement to try and increase activity. I still think the root of the problem needs to be addressed. Too many contests and too many bands. Why do we need 5 cumulative sessions and best 3? Why can't we have 3 sessions and best 2 or even best one? Can we drop contests on the higher bands and replace with activity periods? I was not active this year, partly because of the weather but also because there were too many contests and the times I did go out for 10GHz it was very difficult for those operating portable without KST.

I am not convinced combining 5.7/10/24 GHz is a good idea. It is too many dishes and transverters for one pole unless you combine the feeds and rather too much complication for a portable cumulative. Combining 10 and 24 GHz perhaps but not also 5.7 GHz because while two band feeds are practical 3 band ones are not. I know I could manage it, but not easily and the net result will simply be I only take out at most two of the bands, probably 10GHz and 24 GHz. I have just built a system to allow light weight operation on 24GHz.

24GHz and up are very different in characteristics from 10 GHz and down. 300km is normal on 10GHz, but not on 24GHz. People will spread out to get long 10 GHz contacts and nobody will be in the middle of the country and then the 24GHz QSOs will only be local to the various activity centres. I can see complaints might arise from the 47GHz+ group that they need 24GHz to align 47GHz anyway.

Mike


Re: Advice for portable 23cm beam

Mike Willis <m.j.willis@...>
 

The UHF Compendium, a German publication translated into English in the 1980s. Unavailable now but I have a copy.

Mike

G3RIR wrote:


Mike,

Could you be a little more specific with your reference to the old UHF DX
Book, please.

Do you mean VHF/UHF DX Book? My version doesn't go above 432. I have a
number of other UHF books but can't easily find the flat plate antenna to
which you refer.

73

Neil, G3RIR

-----Original Message-----
From: ukmicrowaves@yahoogroups.com <mailto:ukmicrowaves%40yahoogroups.com> [mailto:ukmicrowaves@yahoogroups.com <mailto:ukmicrowaves%40yahoogroups.com>] On
Behalf Of Mike Willis
Sent: 31 December 2007 10:15
To: ukmicrowaves@yahoogroups.com <mailto:ukmicrowaves%40yahoogroups.com>
Subject: Re: [ukmicrowaves] Advice for portable 23cm beam

Yet another option is to use a flat plate type of antenna that is easy
to pack. A double quad - or several in a vertical stack. This has the
advantage of a broad horizontal beamwidth and a narrow vertical
beamwidth. Gain is lower than a 23 ele Tonna but so is size and weight.
You can make the backplane out of mesh and if ambitious, put a 2.3 GHz
array on the other side. The basic double Quad has 9 dBi of gain, an
array of two stacked vertically should give you 12 dBi.

FRARS have a design on their pages http://www.frars.org.uk/ <http://www.frars.org.uk/> and there is
a double version in the old UHF DX Book. You might also look at G4CYAs'
pages http://www.vhfman.freeuk.com/radio/23cmantennas.html <http://www.vhfman.freeuk.com/radio/23cmantennas.html>

Mike

Yahoo! Groups Links


Re: Advice for portable 23cm beam

G3RIR <g3rir@...>
 

Mike,

Could you be a little more specific with your reference to the old UHF DX
Book, please.

Do you mean VHF/UHF DX Book? My version doesn't go above 432. I have a
number of other UHF books but can't easily find the flat plate antenna to
which you refer.

73

Neil, G3RIR

-----Original Message-----
From: ukmicrowaves@yahoogroups.com [mailto:ukmicrowaves@yahoogroups.com] On
Behalf Of Mike Willis
Sent: 31 December 2007 10:15
To: ukmicrowaves@yahoogroups.com
Subject: Re: [ukmicrowaves] Advice for portable 23cm beam

Yet another option is to use a flat plate type of antenna that is easy
to pack. A double quad - or several in a vertical stack. This has the
advantage of a broad horizontal beamwidth and a narrow vertical
beamwidth. Gain is lower than a 23 ele Tonna but so is size and weight.
You can make the backplane out of mesh and if ambitious, put a 2.3 GHz
array on the other side. The basic double Quad has 9 dBi of gain, an
array of two stacked vertically should give you 12 dBi.

FRARS have a design on their pages http://www.frars.org.uk/ and there is
a double version in the old UHF DX Book. You might also look at G4CYAs'
pages http://www.vhfman.freeuk.com/radio/23cmantennas.html

Mike



Yahoo! Groups Links


turkey dishes

geoffrey pike
 

Well thats the name i give them cause i build them on the outside of a Tesco Turkey dish, anyway see www.cq-tv.com and look at CQ-TV 210.
These were also covered in Radcom with combining details and they all i think came from the UHF Compendium V ,
regards
Geoff Pike
GI0GDP


Yahoo! Answers - Get better answers from someone who knows. Try it now.


Re: Advice for portable 23cm beam

Mike Willis <m.j.willis@...>
 

Yet another option is to use a flat plate type of antenna that is easy to pack. A double quad - or several in a vertical stack. This has the advantage of a broad horizontal beamwidth and a narrow vertical beamwidth. Gain is lower than a 23 ele Tonna but so is size and weight. You can make the backplane out of mesh and if ambitious, put a 2.3 GHz array on the other side. The basic double Quad has 9 dBi of gain, an array of two stacked vertically should give you 12 dBi.

FRARS have a design on their pages http://www.frars.org.uk/ and there is a double version in the old UHF DX Book. You might also look at G4CYAs' pages http://www.vhfman.freeuk.com/radio/23cmantennas.html

Mike


Re: Draft UKUG Contest Calendar/Rules for 2008

Chris G8BKE
 

A few comments peaking purely from a portable operators point of view :-

1. The inclusion of yet another band with 5.6 and 10Ghz risks the "complaint" from the 5.6/10Ghz only operators that time will be spent aligning on 24GHz thus diluting the activity on the lower two bands. On a more personal note, as with Martin 'UKV, another band to take out portable with 5.6 and 10GHz means even more gear to cram in the car and I'm afraid one band could be left at home as a result. On the plus side it does mean that it will allow the use of a lower band to allow dish alignment for 24Ghz.

2. 24GHz is inevitably used for alignment on 47 and 76GHz so the wisdom of dropping it as a scoring band in its own right from the 47/76GHz events is to be questioned? Why not keep it as a scoring band and thus together with the "new" 5.6/10/24GHz event increase the chances of a 24GHz QSO when band conditions are good?

3. July for a 47/76GHz event may produce pleasant weather for operating but it has been seen over the past years that warm and sometimes humid weather at this time is not conducive to low path loss on the mm bands. Thus is it not worth dropping the July event or moving it earlier or later in the year.



73 de Chris G8BKE

Web Site:-
http://myweb.tiscali.co.uk/g8bke/


Re: Advice for portable 23cm beam

SAM JEWELL
 

Happy New Year,

Another option may be WA5VJB's 23cm 'Easy Yagi' design.
This is lightweight, disposible and costs next to nothing to build, whilst having a good 'power to weight' ratio! It is one in the series yagis designed by Kent and extremely popular in the USA.
I need to check where the design has been recently published . I'm not sure that it's on Kent's web page yet. I think it has appeared in CQ VHF.

I would dearly love to receive some reports on the 23cm (and up) activities of the SOTA enthusiasts for the RSGB RADCOM GHz Bands column, please?

73 de Sam, G4DDK


Re: Advice for portable 23cm beam

Liviu Babi <electronicguest@...>
 

Dear Keith,

I use for portable 23 cm operation a small 15 elements yagi, home - made, after DL6WU design software. The construction it's very simple. It was made from copper heat system pipe, 1,5 m long boom and 15 mm diameter; copper 2.5 mm diameter (electrical cables) for elements. Soldered togheter. The adaptation was made from copper-teflon semirig coax.  DL6WU design software will explain you all operations.  

I do not like big (long) antenna for por portable operation. 

My ideea it's not to have small angle in contests. You can easy stack 2 or 4 antenna for better results.

For small antenna also very easy to find a place in the car.

The best results I had with 80 cm, dish antenna (prime focus type) and home made circular feed horn.

Have 23 cm DB6NT transverter 20W out.

 

73's YO4FNG

Liviu 

 

 



----- Original Message ----
From: D&R Friend
To: ukmicrowaves@...
Sent: Monday, December 31, 2007 3:30:15 AM
Subject: [ukmicrowaves] Re: Advice for portable 23cm beam

Hello Keith.

I made my own fit-in-a-suitcase sized one according to the standard
DL6WU design software. No, it's not 'SOTA', but it sure was fun to use
from high locations around the UK back in March-April! There was a
picture including it in Scatterpoint around that time. What you're
planning seems to also suggest a need for mechanical durability, another
significant issue!

Somehow, I don't think small size and 'SOTA' can occur together....

Best 73,

Doug Friend, VK4OE,
Brisbane, Australia.

g8hxe wrote:
> Looking for a reasonably small and lightweight beam antenna for 23cm
> SOTA activity.
>
> The best choice to me looks like the TONNA 23 element or
> possibly the 35 element (a bit big and heavy), does anyone have
> experience of using these in a portable (ie carrying the thing on a
> backpack) environment ?
> Or maybe somebody could suggest something else - looking mainly for SSB
> usage.
>
> Keith.




Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now.


Re: Draft UKUG Contest Calendar/Rules for 2008

Martyn G3UKV
 

Hello John
 
General comment: rules and overview seem very well organised and clear. The tweaks for 2008 seem good overall.
 
Just 2 comments:-
 
1) With a poor home QTH, I mainly operate /P here in Shropshire/Wales - sometimes going portable to unusual places, like Arran and N Ireland. Have doubts about combining 24G with 5.7/10G. On the plus side, it reduces the number of weekends taken up with microwaving (family, miles on the clock, fuel costs etc), but on the minus side in my case it would necessitate 4 completely separate set-ups. [ie 24G tripod/gear/dish/power, ditto 10G,  5.7G mast/gear/dish/power, 2metre talkback ant/gear+PA/power] - believe me that's a lot of stuff - and I use a domestic car, not a mobile shack!! And then some fixed-station guys on the Reflector wonder why we have problems taking and using 'KST as well ??!!
Sometimes Dave G8VZT and other guys from Telford Club come along, but quite often I go-it-alone. In this case, I would only take maximum 2 microwave bands, 24G with 5.7 or 10G. But I guess that's my choice. It may encourage more north/south QSOs on 24G, (sadly lacking in 2007) but I doubt it.
 
2) Small item. In your Excel spreadsheet, you show certificates may be awarded for various sections, and quote "s" - but there is no "s" in the sections listed below the chart. Is that "s" for single op. ?
 
73  Martyn G3UKV
 

----- Original Message -----
From: G3XDY
Sent: Sunday, December 30, 2007 11:37 PM
Subject: [ukmicrowaves] Draft UKUG Contest Calendar/Rules for 2008

May I wish a Happy New Year to all on the reflector

Attached are the draft rules and calendar for UKUG contests during 2008.

A few events have been dropped due to limited support, and the calendar now
includes all the microwave related RSGB contest dates.

The major change from last year is the combination of 24GHz with 5.7GHz and
10GHz in a series of 5 Cumulatives over the summer months. This change has
been made in recognition of the improvement in systems on 24GHz which allow
greater distances to be spanned and non-LOS paths to be worked. Selecting
the best 3 out of 5 events independently for each of the cumulatives means
that portables can select tactics/sites to focus on a specific band for two
or three events and still stay competitive on the other bands.

This change has also allowed the creation of a new 47/76GHz cumulative over
three sessions. These bands are generally low power, tripod based portable
operations, over LOS paths, and fit naturally together in terms of equipment
capabilities.

The popular lowband contests continue, with the addition of an extra event
in December to close out the year.

A number of non-competitive activity days (usually the last Sunday of the
month) are also included.

There is a short window for feedback before this goes to press in
Scatterpoint at the end of the forthcoming week, so I await your input!

73

John G3XDY


Re: Draft UKUG Contest Calendar/Rules for 2008

Grant Hodgson <grant@...>
 

John

Might be worth adding VHF NFD 5-6 July.

regards

Grant

G3XDY wrote:

May I wish a Happy New Year to all on the reflector
Attached are the draft rules and calendar for UKUG contests during 2008.
A few events have been dropped due to limited support, and the calendar now
includes all the microwave related RSGB contest dates.
The major change from last year is the combination of 24GHz with 5.7GHz and
10GHz in a series of 5 Cumulatives over the summer months. This change has
been made in recognition of the improvement in systems on 24GHz which allow
greater distances to be spanned and non-LOS paths to be worked. Selecting
the best 3 out of 5 events independently for each of the cumulatives means
that portables can select tactics/sites to focus on a specific band for two
or three events and still stay competitive on the other bands.
This change has also allowed the creation of a new 47/76GHz cumulative over
three sessions. These bands are generally low power, tripod based portable
operations, over LOS paths, and fit naturally together in terms of equipment
capabilities.
The popular lowband contests continue, with the addition of an extra event
in December to close out the year.
A number of non-competitive activity days (usually the last Sunday of the
month) are also included.
There is a short window for feedback before this goes to press in
Scatterpoint at the end of the forthcoming week, so I await your input!
73
John G3XDY


Re: Advice for portable 23cm beam

D&R Friend <friends@...>
 

Hello Keith.

I made my own fit-in-a-suitcase sized one according to the standard DL6WU design software. No, it's not 'SOTA', but it sure was fun to use from high locations around the UK back in March-April! There was a picture including it in Scatterpoint around that time. What you're planning seems to also suggest a need for mechanical durability, another significant issue!

Somehow, I don't think small size and 'SOTA' can occur together....

Best 73,

Doug Friend, VK4OE,
Brisbane, Australia.


g8hxe wrote:

Looking for a reasonably small and lightweight beam antenna for 23cm
SOTA activity. The best choice to me looks like the TONNA 23 element or
possibly the 35 element (a bit big and heavy), does anyone have
experience of using these in a portable (ie carrying the thing on a
backpack) environment ?
Or maybe somebody could suggest something else - looking mainly for SSB
usage.
Keith.


Advice for portable 23cm beam

g8hxe <g8hxe@...>
 

Looking for a reasonably small and lightweight beam antenna for 23cm
SOTA activity.

The best choice to me looks like the TONNA 23 element or
possibly the 35 element (a bit big and heavy), does anyone have
experience of using these in a portable (ie carrying the thing on a
backpack) environment ?
Or maybe somebody could suggest something else - looking mainly for SSB
usage.

Keith.


Draft UKUG Contest Calendar/Rules for 2008

John Quarmby
 

May I wish a Happy New Year to all on the reflector

Attached are the draft rules and calendar for UKUG contests during 2008.

A few events have been dropped due to limited support, and the calendar now includes all the microwave related RSGB contest dates.

The major change from last year is the combination of 24GHz with 5.7GHz and 10GHz in a series of 5 Cumulatives over the summer months. This change has been made in recognition of the improvement in systems on 24GHz which allow greater distances to be spanned and non-LOS paths to be worked. Selecting the best 3 out of 5 events independently for each of the cumulatives means that portables can select tactics/sites to focus on a specific band for two or three events and still stay competitive on the other bands.

This change has also allowed the creation of a new 47/76GHz cumulative over three sessions. These bands are generally low power, tripod based portable operations, over LOS paths, and fit naturally together in terms of equipment capabilities.

The popular lowband contests continue, with the addition of an extra event in December to close out the year.

A number of non-competitive activity days (usually the last Sunday of the month) are also included.

There is a short window for feedback before this goes to press in Scatterpoint at the end of the forthcoming week, so I await your input!

73

John G3XDY


Wave guide bend 33 to 50 ghz

pa7jb2003 <pa7jb@...>
 

Hello all.
I am looking for a waveguide bend freq 33to50 ghz.
It does not matter which way.
I wish you all a Happy New year and a lot off fun on microwaves.


73 John PA7JB


Re: HEELWEG MICROWAVE 2008

SAM JEWELL
 

Eene,
I plan to come over again this year. However, we have a problem with the old British disease. Strikes. There is a 48 hour stoppage planned for the start of the Heelweg weekend that will close many of the London area airports. I am currently looking to see which regional airports are likely to still be open and have services to Schipol.

Sadly, the HSS Stena Discovery High Speed ferry from Harwich to the Hoek no longer runs and an 8 hour crossing doesn't appeal to a non-sailor!

Out of interest, I found the Stena Discovery HSS again just yesterday! She is tied up at Harland and Wolfe shipyard, Belfast, awaiting a sale or dismantling, according to the guard on the dock gate. It was really sad to see the state she is in now, after just one year out of service. A totally unacceptable end to a fine ship.

Anyway, hope to see everyone at Heelweg on the 19th January.

73 de Sam, G4DDK



Re: 3 cm coax to waveguide (WR90)

Ronny Lembke <m0fwz@...>
 

Hello Liviu,
I think I have a piece of waveguid that I could send to you, along with a few SMA-connectors. Give me your address and I'll send it to you.
73 de Ronny SM7FWZ

Liviu Babi wrote:
Dear Ian,
Tnx for helping mail. Can you made a pictures to your home made 10 GHz tranzition ? Also can you draw all wavweguide on the paper and send in the next mail ? Need all dimensions and details for building one.
It's now very clear to me about SMA or N connectors and I will use only SMA type. 
To buy a waveguide it's not the best solution for me (very expensive) so only way it's to build a good and reliable homebrew.
 
YO4FNG
Liviu

----- Original Message ----
From: Ian Lamb com>
To: ukmicrowaves@yahoogroups.com
Sent: Sunday, December 30, 2007 12:57:06 AM
Subject: RE: [ukmicrowaves] 3 cm coax to waveguide (WR90)

Hello Liviu,

All of my 10GHz transitions are made according to the design at
http://hjem. get2net.dk/ ole_nykjaer/ oz2oe/antenner/ 10ghz_slotant_ sma.jpg
that drawing should answer your questions.

I use sma because all of my changeover relays have sma connectors
although I have an N type transition for interfacing to power meters etc.

If you prefer you can buy WG16 - sma & N type transitions from various
suppliers including
http://micro- mechanik. de/product_ info.php? cPath=30_ 24&products_ id=43&osCsid= 1002d577426d17e2 9e38f35b19dfa3da

Good Luck & 73 .. Ian
G8KQW



____________ _________ _________ __

From: ukmicrowaves@ yahoogroups. com on behalf of Liviu Babi
Sent: Sat 29/12/2007 22:04
To: ukmicrowaves@ yahoogroups. com
Subject: [ukmicrowaves] 3 cm coax to waveguide (WR90)

Hello,
I'm YO4FNG, Liviu from KN44HD. I am beginner in 3 cm band. Have few questions: I want to build a coax to waveguide for 3 cm band (WR90) following the details from http://www.50mhzand up.org/pg98. pdf <http://www.50mhzand up.org/pg98. pdf> .
1. How many screws must I use ?
2. Which one is better : SMA connector or N connector. Have also SMA and N connectors for copper-teflon semirigid coax. I saw on markets (for sale) waveguides with N and SMA connectors !
3. For building can I use 1 mm thickness brass ? (for the moment I have only 200mW out from DB6NT transvreter, but I will increase to 10 W in next future)
4. How many milimeters must build the monopole's height ? (6.8 mm height and 2 mm diameter it's correct ?)

Tnx in advance for help,
YO4FNG Liviu

____________ _________ _________ _________ _________ _________ _
Never miss a thing. Make Yahoo your home page.
http://www.yahoo. com/r/hs <http://www.yahoo. com/r/hs>




Looking for last minute shopping deals? Find them fast with Yahoo! Search.


Looking for last minute shopping deals? Find them fast with Yahoo! Search.


Re: manuals

mw1fgq <owen.home@...>
 

--- In ukmicrowaves@yahoogroups.com, Rainer <df6na@...> wrote:

Hi,

I need the following manuals
pro-bel
6063
6064
6251
Rainer
If memory serves correctly the 6063 and 6064 are 3RU and 1RU empty
Rack Frames so they may not have useful manuals - I can't recall if
the PSUs were separately specified. I may be able to find someone
with the 6251 analogue video distribution amplifier manual if you
struggle, they are quite old now.
Regards
John
MW1FGQ


manuals

DF6NA Rainer
 

Hi,

I need the following manuals

RACAL
3100
9423 also data sheet
9478
9480

pro-bel
6063
6064
6251

Hopefully someone could help me. Originals, photo copies or PDF's ok.

Happy New Year !
vy 73, Rainer


VHF/UHF/SHF Online Toplist:
http://www.vhf-dx.net/top.html

DF6NA Homepage:
http://www.df6na.de/

Amateurfunk-Flohmarkt:
http://www.afu-flohmarkt.de/

VHF-DX.net:
http://www.vhf-dx.net/


Re: 3 cm coax to waveguide (WR90)

Liviu Babi <electronicguest@...>
 

Dear Ian,
Tnx for helping mail. Can you made a pictures to your home made 10 GHz tranzition ? Also can you draw all wavweguide on the paper and send in the next mail ? Need all dimensions and details for building one.
It's now very clear to me about SMA or N connectors and I will use only SMA type. 
To buy a waveguide it's not the best solution for me (very expensive) so only way it's to build a good and reliable homebrew.
 
YO4FNG
Liviu

----- Original Message ----
From: Ian Lamb
To: ukmicrowaves@...
Sent: Sunday, December 30, 2007 12:57:06 AM
Subject: RE: [ukmicrowaves] 3 cm coax to waveguide (WR90)

Hello Liviu,

All of my 10GHz transitions are made according to the design at
http://hjem. get2net.dk/ ole_nykjaer/ oz2oe/antenner/ 10ghz_slotant_ sma.jpg
that drawing should answer your questions.

I use sma because all of my changeover relays have sma connectors
although I have an N type transition for interfacing to power meters etc.

If you prefer you can buy WG16 - sma & N type transitions from various
suppliers including
http://micro- mechanik. de/product_ info.php? cPath=30_ 24&products_ id=43&osCsid= 1002d577426d17e2 9e38f35b19dfa3da

Good Luck & 73 .. Ian
G8KQW



____________ _________ _________ __

From: ukmicrowaves@ yahoogroups. com on behalf of Liviu Babi
Sent: Sat 29/12/2007 22:04
To: ukmicrowaves@ yahoogroups. com
Subject: [ukmicrowaves] 3 cm coax to waveguide (WR90)

Hello,
I'm YO4FNG, Liviu from KN44HD. I am beginner in 3 cm band. Have few questions: I want to build a coax to waveguide for 3 cm band (WR90) following the details from http://www.50mhzand up.org/pg98. pdf <http://www.50mhzand up.org/pg98. pdf> .
1. How many screws must I use ?
2. Which one is better : SMA connector or N connector. Have also SMA and N connectors for copper-teflon semirigid coax. I saw on markets (for sale) waveguides with N and SMA connectors !
3. For building can I use 1 mm thickness brass ? (for the moment I have only 200mW out from DB6NT transvreter, but I will increase to 10 W in next future)
4. How many milimeters must build the monopole's height ? (6.8 mm height and 2 mm diameter it's correct ?)

Tnx in advance for help,
YO4FNG Liviu

____________ _________ _________ _________ _________ _________ _
Never miss a thing. Make Yahoo your home page.
http://www.yahoo. com/r/hs <http://www.yahoo. com/r/hs>




Looking for last minute shopping deals? Find them fast with Yahoo! Search.


Re: 3 cm coax to waveguide (WR90)

D&R Friend <friends@...>
 

Hello Liviu (and others) and greetings from Australia!

My experience in making WR90 transitions is that they are fairly easy to get going, just as long as you make them carefully. As others have said, the various reference books will give you good dimensions to use.

The essential difference between commercial and amateur made ones is that, using the adjustment screws, we can 'get away' with having good useable bandwidth over a relatively small, say 100 to 500 MHz range at 10.3 GHz. This is compared to commercially made ones which are usually intended for a gigahertz or more bandwidth, even the whole four gigahertz of 'X-band' for top-of-the-range HP ones.

To optimise performance of the one(s) you make (adjusting the screws and/or the length of the probe for best return loss), you will need to use a known good WR90 (WG16) load and a coaxial directional coupler (presuming that your RF output is on a coaxial socket, which is usual these days), plus a microwave power meter or other power measuring apparatus. To help protect the RF output transistor/FET from severe reflected power, a 10 GHz coaxial isolator would be good, or perhaps a 10 dB (or more) attenuator if you can still do your measurements at a lower power level.

If you don't have these items of test equipment, perhaps another amateur you know has them, or someone in Europe may be willing to adjust your creation for you! I know that back in the 1980's (and earlier!) uWave amateurs usually made transitions and only hoped for good performance because they didn't have access to test equipment. Results were probably quite variable.

Based on my first home-made transition which I incorporated into a horn antenna (quite a few years ago now, picture can be seen at: http://www.qsl.net/oh2aue/aue_oe_4.jpg ), I do think that being able to adjust for best return loss will be very helpful to you. I was able to improve the RL on mine from about 5 dB to around 25 dB, just using two screws. And you may be interested to know that I made this transition with 3/4 of a waveguide wavelength from the probe to the short, not the usual 1/4 wavelength. This allowed one adjustment screw to be located between the probe and the short and the other adjustment screw the same distance on the waveguide output side of the probe.

Some other people do their RL adjustments by varying the position of the waveguide short avoiding the need for adjusting screws, but this requires a different sort of construction (good metal-to-metal contact all around) which you may consider difficult to achieve.

Whether you make yours with an SMA connector of an 'N' connector is entirely up to you. The only possible difficulty with using an 'N' connector is that the flange is usually bigger than the distance from the probe to the waveguide short. Again, this is not an impossible challenge which ever way you fit the 'N', but it does make the idea of a 3/4 wavelength transition more attractive.

Liviu, I don't want you to start thinking that these things are impossible to make - as I said at the beginning, they are fairly easy to get going! But without access to test equipment there are some difficulties in knowing that you have optimum performance. If I can be of any further assistance, please feel free to contact me again, or other fellows on this 'list' will probably be also willing to assist.

73,

Doug Friend, VK4OE,
Brisbane, Australia,
QG62ML.


Liviu Babi wrote:

Hello,
I'm YO4FNG, Liviu from KN44HD. I am beginner in 3 cm band. Have few
questions: I want to build a coax to waveguide for 3 cm band (WR90)
following the details from http://www.50mhzandup.org/pg98.pdf .
1. How many screws must I use ?
2. Which one is better : SMA connector or N connector. Have also SMA
and N connectors for copper-teflon semirigid coax. I saw on markets
(for sale) waveguides with N and SMA connectors !
3. For building can I use 1 mm thickness brass ? (for the moment I
have only 200mW out from DB6NT transverter, but I will increase to
10 W in next future)
4. How many millimeters must build the monopole's height ? (6.8 mm
height and 2 mm diameter it's correct?)
Tnx in advance for help,
YO4FNG Liviu