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Re: LPF for 3.5 GHz?
eai3ld <dako_ger@...>
Hello Grant,
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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:
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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
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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
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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
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Re: LPF for 3.5 GHz?
Grant Hodgson <grant@...>
Daniel
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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,
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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
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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
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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
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Re: IO73
Ray <gm4cxm@...>
Thanks Mike, much appreciated.
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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:
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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
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Re: Smith chart
Michael Scott
Nice one Andy, It prints very cleanly from the
PDF.
73, Mike
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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
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Re: Smith chart
mikeg3pfr@...
In a message dated 20/02/2008 19:22:11 GMT Standard Time,
g3lyp@... writes:
Seconded!
Regards, Mike, G3PFR
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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
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Re: Scatterpoint Feb 2008
Andy Talbot <andy.g4jnt@...>
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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
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Re: 24GHz
SAM JEWELL
Could be....
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Thanks for the letter. Arrived today. Sam Richard Newstead wrote:
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Re: IO73
g4blh <g4blh@...>
Hi Ray,
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
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Re: 24GHz
Richard Newstead <g3cwi@...>
--- In ukmicrowaves@..., <JFELL@...> wrote:
I'm expecting to find depression control of use on shorter paths from Snowdon on Sunday. 73 Richard G3CWI
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Re: Smith chart
some take things a bit too far ;-)
http://my.ece.ucsb.edu/sanabria/tattoo.html Paul G0ILO. --- In ukmicrowaves@..., "Andy Talbot" <andy.g4jnt@...> wrote:
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