Date   

Re: LPF for 3.5 GHz?

eai3ld <dako_ger@...>
 

Hello Grant,

unfortunately purchasing components from minicircuits is very costly
from Germany as there is no distribution for small quantities.
I would have to order from the States and the cost of shipping and tax
is in no relationship to the stuff I would like to buy.

Where do you buy thoses components? How do minicircuits distribute in
the U.K.?

Daniel

--- In ukmicrowaves@..., Grant Hodgson <grant@...> wrote:

Daniel

The LFCN-3400 from Mini-Circuits should do the job.

Loses in 0.8mm FR4 at 3.5GHz might not be as bad as you think,
especially if the track lengths are kept as short as possible. I've
used FR4 up to 12GHz ok.

regards

Grant G8UBN

eai3ld wrote:


Hi all,

I am building a tracking generator for my Advantest R4131 spectrum
analyzer and need a low-paas filter with a cut-off frequency of
around 3.5GHz. The filter should be reasonably steep. I do not have
much of a chance to do good mechanical work here (coaxial LP-filters),
but PCB making is not a problem.
However, I will be limited to FR4 (0,5 or 0,8 or 1,5mm thickness) as
I have no other photosensitve laminate available. Losses are rapidly
increasing beyond 2 GHz for FR4, this seems to be a major problem when
designing a micro-strip filter. But I really see not much of another
alternative.

Has anybody on this list faced a similar problem in the past (and
solved it!)? Any help, also regarding other Microwave LPF designs
would be of great help.

There was a posting about LPF-filters behind microwave
transverters/PAs in the past on this newsgroup. Anybody designed a
filter for 9cms?

Thanks in advance

Daniel, DL3IAE


Re: Use of attenuators

Mark GM4ISM <gm4ism@...>
 

Richard
Assuming the coupler is SMA, you can get an idea by putting the best load you have ( I think 1 had about 27dB ret loss)
If the value you observe is near the known load return loss (written on it I think) then you will have an idea of the rough directivity of the coupler.
the errors when return loss of the reference and directivity of the coupler are close are quite large, but if you get a reading of return loss from the coupler of say 20 dB, with a load of 27dB you are acutually reading the directivity of the coupler as the largest factor.
Somewhere in the old microwave newsletter technical collection is a nice graph of the range of uncertainty.
I will try to find it
regards
mark
PS I hope to be QRV on Sunday morning, but the path is quite long and obstructed this end. I may well leave my TX on high power in your direction, so u can listen for it and phone me if u hear it
Cheers
Mark GM4ISM
 

----- Original Message -----
Sent: Thursday, February 21, 2008 12:44 PM
Subject: [ukmicrowaves] Use of attenuators

I have just received some microwave attenuators - good old ebay. The
values are 6/6/11/13/15dB. In use I wonder if there is any advantage
in using them in a particular order? For example in a power
attenuation role I guess it might be best to have a smaller
attenuator first to reduce dissipation in a subsequent larger one? Is
that sensible and are there other considerations?

Having fixed a dodgy lead for the sensor on the Boonton meter and
with a nice 10mW 12GHz sensor I am nearly set to make some meaningful
measurements. Is there any clever way to deduce the directivity of a
coupler at 10GHz with very little test gear?

73

Richard
G3CWI


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Use of attenuators

Richard Newstead <g3cwi@...>
 

I have just received some microwave attenuators - good old ebay. The
values are 6/6/11/13/15dB. In use I wonder if there is any advantage
in using them in a particular order? For example in a power
attenuation role I guess it might be best to have a smaller
attenuator first to reduce dissipation in a subsequent larger one? Is
that sensible and are there other considerations?

Having fixed a dodgy lead for the sensor on the Boonton meter and
with a nice 10mW 12GHz sensor I am nearly set to make some meaningful
measurements. Is there any clever way to deduce the directivity of a
coupler at 10GHz with very little test gear?

73

Richard
G3CWI


Re: In praise of Fruit Flies

JFELL@...
 

Nice poem Richard !
All this hill topping takes me back to the early 10GHz narrowband days in the late 70s .The thought of all those Alpine people on speed does seem a tad alarming ?
You can get medication for "depression" on Snowdon .....
Mind you 24Hr contesting on Dartmoor in May was no picnic - interesting watching bomb craters freeze .
Maybe we will bump into you when we are in the Lakes at Ullswater in late March.

Hope you have a safe /plentiful DX day out on Sunday.

73
John
G0API/W


Re: LPF for 3.5 GHz?

Grant Hodgson <grant@...>
 

Daniel

The LFCN-3400 from Mini-Circuits should do the job.

Loses in 0.8mm FR4 at 3.5GHz might not be as bad as you think, especially if the track lengths are kept as short as possible. I've used FR4 up to 12GHz ok.

regards

Grant G8UBN

eai3ld wrote:

Hi all,
I am building a tracking generator for my Advantest R4131 spectrum
analyzer and need a low-paas filter with a cut-off frequency of
around 3.5GHz. The filter should be reasonably steep. I do not have
much of a chance to do good mechanical work here (coaxial LP-filters),
but PCB making is not a problem.
However, I will be limited to FR4 (0,5 or 0,8 or 1,5mm thickness) as
I have no other photosensitve laminate available. Losses are rapidly
increasing beyond 2 GHz for FR4, this seems to be a major problem when
designing a micro-strip filter. But I really see not much of another
alternative.
Has anybody on this list faced a similar problem in the past (and
solved it!)? Any help, also regarding other Microwave LPF designs
would be of great help.
There was a posting about LPF-filters behind microwave
transverters/PAs in the past on this newsgroup. Anybody designed a
filter for 9cms?
Thanks in advance
Daniel, DL3IAE


LPF for 3.5 GHz?

eai3ld <eai3ld@...>
 

Hi all,

I am building a tracking generator for my Advantest R4131 spectrum
analyzer and need a low-paas filter with a cut-off frequency of
around 3.5GHz. The filter should be reasonably steep. I do not have
much of a chance to do good mechanical work here (coaxial LP-filters),
but PCB making is not a problem.
However, I will be limited to FR4 (0,5 or 0,8 or 1,5mm thickness) as
I have no other photosensitve laminate available. Losses are rapidly
increasing beyond 2 GHz for FR4, this seems to be a major problem when
designing a micro-strip filter. But I really see not much of another
alternative.

Has anybody on this list faced a similar problem in the past (and
solved it!)? Any help, also regarding other Microwave LPF designs
would be of great help.

There was a posting about LPF-filters behind microwave
transverters/PAs in the past on this newsgroup. Anybody designed a
filter for 9cms?

Thanks in advance

Daniel, DL3IAE


Re: IO73

Richard Newstead <g3cwi@...>
 

Dear All

After back-calculating I have moved my 10G activity time on Snowdon
to 10:45 on Sunday. It was not looking practical to get there by
0930. The WX is currently forecast is for light showers. Rain will
stop play for the microwave gear so I will monitor the forecasts and
will post final details here, either on Saturday night or very early
Sunday morning.

I will have sufficient battery power for about 1 hour of operation
and will be with my son.

Dont panic if you miss me. If 10G catches on with the SOTA crowd,
IO73 will quickly become common again.

73

Richard
G3CWI


Re: 24GHz

g0ewn191 <g0ewn191@...>
 

I have been following the thread with interest and make the following
observations.
The good conditions at the weekend/ Monday were as a result of the
formation of a duct under high pressure conditions. Exceptionally cold
air meant that total moisture content was very low in the lower
atmosphere--perfect for mm wave contacts. Very sharp boundaries/
gradients in temperature/ humidity formed--again ideal for mm wave
contacts. The 'launch' angle is very critical under these
circumstances and with narrow beams. Elevation control would allow the
launch angle to be adjusted for best fit.
In total I made 4 qso,s over 240kms--Sunday G4DDK, Monday G4EAT, G4DDK
and G8APZ. Tests on Sunday with G4EAT in the morning, G4DDK evening on
3cms showed the band behaving almost as LOS with end stopping
signals--definately the right conditions for testing the higher
microwave bands.
Checking the setting on my dish showed I had a negative elevation of
around 1.5 degrees--in other words I was beaming at the horizon for my
location (230m asl.) On both nights I had to wait until 9.30pm ish
before the bands opened, which is significant as others at lower
elevations found the ducting accessable shortly after dark.
As a rule of thumb, for troposcatter a slight degree of elevation of
half the dish's beamwidth is useful. For LOS both beams should be
fully aligned to start with. In all cases fine elevation control is
very useful for peaking signals. RS requires full elevation control
to get the most out of the mode, though DX contacts are usually at
troposcatter type elevation angles.
The importance of cold temperatures is evident by a simple
scattergraph--almost all dx mm wave contacts are winter months--RS
being the exception. All my DX on 24ghz has taken place between
November and February.

Best wishes, Gordon G0EWN


Re: IO73

Ray <gm4cxm@...>
 

Thanks Mike, much appreciated.
I will endeavor to leave my 4x 44el's beaming IO73 and the rig on
1297.500 FM in the hope of a contact at the weekend.
73 Ray GM4CXM
IO75TW

150w available but will be backed off for FM!

--- In ukmicrowaves@..., "g4blh" <g4blh@...> wrote:

Hi Ray,

Gerald OGI normally only has low power on 23cms (mW).
I have sent him an Email asking what he will be using, will
post it on here when I get the reply.
With reference to Gerald GW4OIG potential North Wales SOTA
activations this coming weekend, Gerald has Emailed me the following
info.

"At the moment I have been using the beam horizontal, though I will
be making an adaptor plate before the activation so it can be
used vertically polarised. I will be taking a small 3.2m pole with
me and can drop this to change polarisation if needs be. I think
horizontal polarisation will have the best potential for distance
contacts, but realise not everyone has a beam.

The nominal power will be 280mW from the handheld - no power
amplifier as yet and unlikely to get one sorted by the weekend. I
have plans for a Mitsubishi brick to give be 10 watts or more
eventually."

Regards, Mike G4BLH


10 GHz testing next saturday

bart_ghz <shf2@...>
 

Hello,

Next saturday afternoon I hope to do some testing on 3 cm with my new
setup.
The locator will probably be JO20ss or as an alternative JO20mw.
I'll be using 3W and 70 cm prime focus dish.
I will not have 2m ssb,but i will listening on my car tranceiver on
145.425 MHz.
I'll also be on KST chat.
So any qso (ssb and cw) will be appreciated.

regards on7bv Bart


Re: Smith chart

Michael Scott
 

Nice one Andy, It prints very cleanly from the PDF.
 
73, Mike

----- Original Message -----
Sent: Wednesday, February 20, 2008 4:06 PM
Subject: [ukmicrowaves] Smith chart


In praise of Fruit Flies

Richard Newstead <g3cwi@...>
 

Geneticists like fruit flies. Their short lifespan allows genetic
variation to be studied in relative short time periods. In much the
same way, my microwave system has developed rapidly having been
adapted and improved over the course of over ten outings to the
hills.

On each of these outing I have been interested to note the response
of the people that have called me and I have observed that the
methods use by some people have made my life much easier. In an
effort to bring out these points I have written a short article
which, in my characteristic writing style, has the apparently
meaningless heading "Life in the Zone".

http://www.sotabeams.co.uk/Downloads/Life%20in%20the%20Zone.pdf

I hope that you will find it interesting!

73

Richard
G3CWI


Re: Smith chart

mikeg3pfr@...
 

In a message dated 20/02/2008 19:22:11 GMT Standard Time, g3lyp@... writes:
Nice one Andy, It prints very cleanly from the PDF.
 
Seconded!
 
Regards, Mike, G3PFR


Re: In praise of Fruit Flies

mikeg3pfr@...
 

In a message dated 20/02/2008 19:05:23 GMT Standard Time, g3cwi@... writes:
I hope that you will find it interesting!
 
Thanks, Richard - yes, very interesting, as it changes the face of lightweight microwave operation in a way which was not previously possible. Keep up the good work - you have certainly stirred up some activity and we can all benefit from that!
 
Regards, Mike, G3PFR


Re: Scatterpoint Feb 2008

Andy Talbot <andy.g4jnt@...>
 


Re: Scatterpoint Feb 2008

Peter Day <microwaves@...>
 

Andy Talbot wrote:
No, be fair. After 50 years you'd be getting nostalgic about black spot fets and SOTA operation while marvelling at the beginners building chip-and-bond kits for the 3THz band.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ and pigs might fly :-)

In the immortal words of a certain Orangeman.. "NEVER, NEVER NEVER! :-))

73

Peter, G3PHO


Re: 24GHz

SAM JEWELL
 

Could be....
Thanks for the letter. Arrived today.
Sam


Richard Newstead wrote:

--- In ukmicrowaves@yahoogroups.com, wrote:
>
>
> Hi Sam,
> In order to nail this issue I would (again) recommend everyone
>adopts elevation control

I'm expecting to find depression control of use on shorter paths from
Snowdon on Sunday.

73

Richard
G3CWI



Re: IO73

g4blh <g4blh@...>
 

Hi Ray,

Gerald OGI normally only has low power on 23cms (mW).
I have sent him an Email asking what he will be using, will
post it on here when I get the reply.
With reference to Gerald GW4OIG potential North Wales SOTA
activations this coming weekend, Gerald has Emailed me the following
info.

"At the moment I have been using the beam horizontal, though I will
be making an adaptor plate before the activation so it can be
used vertically polarised. I will be taking a small 3.2m pole with
me and can drop this to change polarisation if needs be. I think
horizontal polarisation will have the best potential for distance
contacts, but realise not everyone has a beam.

The nominal power will be 280mW from the handheld - no power
amplifier as yet and unlikely to get one sorted by the weekend. I
have plans for a Mitsubishi brick to give be 10 watts or more
eventually."

Regards, Mike G4BLH


Re: 24GHz

Richard Newstead <g3cwi@...>
 

--- In ukmicrowaves@..., <JFELL@...> wrote:


Hi Sam,
In order to nail this issue I would (again) recommend everyone
adopts elevation control
I'm expecting to find depression control of use on shorter paths from
Snowdon on Sunday.

73

Richard
G3CWI


Re: Smith chart

G0ILO
 

some take things a bit too far ;-)

http://my.ece.ucsb.edu/sanabria/tattoo.html

Paul G0ILO.

--- In ukmicrowaves@..., "Andy Talbot" <andy.g4jnt@...>
wrote:

A good quality PDF

http://www.printfreegraphpaper.com/gp/smith-a4.pdf


--
Andy G4JNT
www.scrbg.org/g4jnt