Date   

Tonight - Microwave Activity Night, 8/10/2009, 8:00 pm

ukmicrowaves@...
 

Reminder from:   ukmicrowaves Yahoo! Group
 
Title:   Tonight - Microwave Activity Night
 
Date:   Monday August 10, 2009
Time:   8:00 pm - 9:00 pm
Repeats:   This event repeats every week.
Notes:   Monday nights are traditionally microwave activity nights. Why not try listening around at 20:00 local time? Better still, call CQ! Consider using KST to co-ordinate activities:

http://www.on4kst.com/chat/start.php
 
Copyright © 2009  Yahoo! Inc. All Rights Reserved | Terms of Service | Privacy Policy


Chuff, chuff, chuff, chuff chuff, chuff, squelch! (1)

Christopher Bartram <cbartram@...>
 

The 'steam train effect' on VHF signals is caused by the signal scattered by a
moving reflector - typically an aircraft - interfering with a signal propagated
over a static path. The 'chuff, chuff, sound is usually caused in an AM receiver
(which includes SSB in this context) by the receiver AGC trying to follow the
relatively slow (~1Hz-ish) changes in signal strength caused by the the two
signals adding and subtracting as their relative amplitude and phase changes.
A similar thing happens in FM receivers below limiting but the mechanism is
different

Given the usual velocities of aircraft, the doppler shift on the signal
scattered by one is likely to be in the region of 1kHz at 10GHz. That's too
fast for most AGC systems to follow, and the chuff-chuffing becomes a tone. In
practice, because we tend to hear only the signal scattered from the aircraft,
the norm on the microwave bands is to hear a frequency shifted signal, but not
to notice the interference effects. I have heard chuffing on the microwave bands
from (relatively slow moving) cars, and even pedestrians, but they tend not to
high enough to provide useful extended propagation :-)

I'm pretty sure from his description that Tony noticed simple scattering from
aircraft.

Vy 73

Chris
GW4DGU


(1) FWIW the subject line is taken from the chorus of a 1970's song - the
title of which I've long forgotten - by a very funny man called Mike Absolom.
The song, which had the heroine tied to a railway track, contained one of my
all- time favourite lyric lines: 'She said to me you virile brute, don't be so
eclectic, British Rail have changed their chuff-chuff trains to electric ...'


Re: 10Ghz in EI today... update!

Richard Newstead <g3cwi@...>
 

--- In ukmicrowaves@yahoogroups.com, Dave Ackrill <dave.g0dja@...> wrote:

The classic way to describe aircraft scatter is that you hear a 'chuff,
chuff' type of noise. Often described as being like an old steam train
moving away from a station.
Dave

I have not heard anything sounding like that on 10GHz. I have heard occasional strong pings and fairly constant level signals drifting with Doppler - both of which I assume are due to aircraft. But no steam trains.

Can anyone confirm if the steam train effect happens on 10GHz?

73

Richard
G3CWI


Re: 10Ghz in EI today... update!

Andy Talbot <andy.g4jnt@...>
 

http://www.g4jnt.com/beacons.htm (scroll down the page to about last third-)

then http://www.g4jnt.com/BCNKEYER.zip


Andy
www.g4jnt.com



2009/8/9 Dave Ackrill <dave.g0dja@tiscali.co.uk>:



Richard Newstead wrote:
--- In ukmicrowaves@yahoogroups.com, "Tony Gallagher"
I think my next purchase is a cw beacon keyer for setting up. Can >anyone
recommend something cheap?
The one I went for was the one designed by G4FRS and G4DDK see
http://hamradio.lakki.iki.fi/new/Software/PIC/Beacon%20keyer/

The great thing about this design is that it's not expensive and you can
decide what you want to have programmed into the message.

If you have the programming board (which I decided to buy as well for
other PIC projects) then you can program up any number of chips with
various messages on them.

Dave (G0DJA)


Re: 10Ghz in EI today... update!

Dave Ackrill <dave.g0dja@...>
 

Richard Newstead wrote:
--- In ukmicrowaves@yahoogroups.com, "Tony Gallagher"
I think my next purchase is a cw beacon keyer for setting up. Can >anyone recommend something cheap?
The one I went for was the one designed by G4FRS and G4DDK see http://hamradio.lakki.iki.fi/new/Software/PIC/Beacon%20keyer/

The great thing about this design is that it's not expensive and you can decide what you want to have programmed into the message.

If you have the programming board (which I decided to buy as well for other PIC projects) then you can program up any number of chips with various messages on them.

Dave (G0DJA)


Re: 10Ghz in EI today... update!

Dave Ackrill <dave.g0dja@...>
 

Tony Gallagher wrote:
I headed to IO52MT on Woodcock Hill Limerick, unfortunately no qso was possible here, distance was about 130Km and we were both over 600-700ft ASL. I was a little disapointed!
What was interesting was we both heard each on very quick burst on FM, about S6, The bursts were about 5 seconds and had alot of very very fast fluttering. I wonder was this tropo or some sort of scatter?
130km is a bit ambitious for a first contact, and the propagation you describe sounds very like aircraft scatter.

If it had been rain scatter, that would sound more like an Aurora signal.

The classic way to describe aircraft scatter is that you hear a 'chuff, chuff' type of noise. Often described as being like an old steam train moving away from a station.

Dave (G0DJA)


Re: 10Ghz in EI today... update!

Tony Gallagher <tony_g_ireland@...>
 

Perfect,
Thanks Richard


Tony

--- In ukmicrowaves@yahoogroups.com, "Richard Newstead" <g3cwi@...> wrote:

--- In ukmicrowaves@yahoogroups.com, "Tony Gallagher"
I think my next purchase is a cw beacon keyer for setting up. Can >anyone recommend something cheap?
http://www.hamgadgets.com/store/product_info.php?products_id=89

73

Richard
G3CWI


Re: 10Ghz in EI today... update!

Richard Newstead <g3cwi@...>
 

--- In ukmicrowaves@yahoogroups.com, "Tony Gallagher"
I think my next purchase is a cw beacon keyer for setting up. Can >anyone recommend something cheap?
http://www.hamgadgets.com/store/product_info.php?products_id=89

73

Richard
G3CWI


10Ghz in EI today... update!

Tony Gallagher <tony_g_ireland@...>
 

Hi everyone,
Worked EI3IX/EI7FAB/P today from Galway IO53PK or there abouts. They were in IO53LU
Distance was about 50-60Km. Signals 9+ were exchanged. Tried FM on 10Ghz for the first time today, which was pretty nice!
I headed to IO52MT on Woodcock Hill Limerick, unfortunately no qso was possible here, distance was about 130Km and we were both over 600-700ft ASL. I was a little disapointed!
What was interesting was we both heard each on very quick burst on FM, about S6, The bursts were about 5 seconds and had alot of very very fast fluttering.
I wonder was this tropo or some sort of scatter?

For setting the dishes bearing, I used Martyns method of standing infront of the dish. This worked perfectly!!! Thanks for that.

I think my next purchase is a cw beacon keyer for setting up. Can anyone recommend something cheap? I'm getting hoarse calling and calling!!

Regards

Tony
EI4GHB


Re: beam and coax

Julie & Stephen <stephen_hayman@...>
 

Hello Chris - if you new to 23cm then *welcome* - it is one of the best microwave bands..
 
Keep the *rule of thumb* for any coax loss at 1dB or less - not sure of antenna prices in the UK but here in ZL we build our own, because we can't buy them locally  - a loop Yayi - 33 elements will work great - cost to build is about 5 pound. A days work to cut the strips and mount on a 19mm boom. They are not critical in dimensions - the word would be less forgiving as compared to say a Yagi design.
 
Get something up in the air first - I used for many year a single loop Yagi and only 25 watts and had some great internal ZL contacts (350km) and beacons (550km) including VK many times at (2100km) portable - so when the troposheric ducting is in, she is magic..
 
The good thing about 23cm, you can work many to begin with, and over time you can upgrade your station. It's an active band. Since my days of 25 watts and a loop Yagi (and a lot of activity growth) have upgraded to 150 watts (W6PQL) and a stack of 4 Yagi's(120 elements) in total. That really helped with my limited home station QTH...
 
Cheers - Steve
 
 
 

 --- On Sat, 8/8/09, Chris wrote:

From: Chris
Subject: [ukmicrowaves] beam and coax
To: ukmicrowaves@...
Received: Saturday, 8 August, 2009, 9:28 PM

 
Hi I have just put the 23cm unit into my IC910 and I need some help with what beam and coax to use on the 23cm band
thanks Chris GM4YLN


Re: beam and coax

g4bao
 

Hello Chris,
The WIMOs are quite pricey, but I've heard nothing but good said about them. I use four 23 element Tonnas, but ran a single one for many years. They are a little fragile but have the advantage (if you live surrounded by neighbours like I do) that the visual impact is less than most Freeview TV antennas. Also if you had plans for higher bands, a 45cm sky Dish fits INSIDE a box of four Tonnas (have a look on www.g4bao.com for a picture of my setup) giving you a nice multiband setup with minimum space.

As for feeder, I echo Graham, FSJ450 or LDF450 works well, but if you can get the PA and preamp on the mast, you can use UR67. I have a masthead preamp and use UR67 as downlead  for receive, and I also diplex the 144MHz IF for 3cms down the same coax. I have a separate TX feed of FSJ4-50 as my PA is in the loft.

There are many combinations of antenna gain and feeder loss possible so you need to get your calculator out and work out what suits your particular location best.

73
John             
-- 
G4BAO
QRV 23,9,3 and 1.2cm
Beacon keeper GB3CAM/24GHz
http://www.g4bao.com 


Re: beam and coax

John Quarmby
 

Hi Chris

It all depends....

How much space do you have on your mast for the antenna? If it is limited then a single long yagi would be a good bet (eg the 67 ele Wimo/SHF or 55ele Tonna). If you have the vertical space available, stacked shorter yagis will give more horizontal beamwidth and similar gain (eg 2 x 44ele or 28ele Wimo's or 2 of the 23/35 ele Tonnas). I have used a box of four 23 ele Tonnas for for many years with good results.

As for coax, it depends on how long a run you need and the weight involved, obviously the lower loss the better from an RF viewpoint. If you can find some Andrew LDF4-50 that would be ideal, but it's too rigid for a loop round a rotator, where FSJ4-50 or the Ecoflex cables would work better. Ecoflex (10 or 15mm) may also be worth considering for the main run. Avoid RG213/UR67 as its loss is high at 1.3GHz. To some extent you can trade off feeder loss against more watts in the shack if you use a masthead preamp.

A good masthead preamp is well worthwhile, the choice of design may depend on whether you have any cellular base stations in your immediate vicinity.

73

John G3XDY

----- Original Message -----
From: "Chris" <chris.yln@blueyonder.co.uk>
To: <ukmicrowaves@yahoogroups.com>
Sent: Saturday, August 08, 2009 9:28 AM
Subject: [ukmicrowaves] beam and coax


Hi I have just put the 23cm unit into my IC910 and I need some help with what beam and coax to use on the 23cm band
thanks Chris GM4YLN



------------------------------------

Yahoo! Groups Links



Re: beam and coax

Graham - G4FSG
 

--- In ukmicrowaves@yahoogroups.com, "Chris" <chris.yln@...> wrote:

Hi I have just put the 23cm unit into my IC910 and I need some help
with what beam and coax to use on the 23cm band
thanks Chris GM4YLN
Chris

I use a Wimo 44 element on 23cms (and Wimo antennas on 70cm and 2m) and
have found it very good in both performance and quality. Of course, the
general rule is 'get as much metal in the sky as possible' so a 67 el
would be even better!!

The answer to 'what feeder' is more difficult - it depends to a degree
on the length of feeder and whether you are going to run a masthead
pre-amp. A fair compromise is Ecoflex 10 or 15 depending on the length.
Even better would be LDF4-50 (but only just better than Eco15 at 23cm).
Under lift conditions then any of these will be OK however long the run
but if you want to work DX under flat condx then a masthead preamp
(G4DDK?) and reasonable power out is needed.

73

Graham - G4FSG


Re: Beacons and gardening

Willis, MJ (Michael) <mike.willis@...>
 

The same thing happens with shacks when amateurs are on the air rather than gardening. It is just as well overgrown trees are good supports for HF stealth dipoles.
 
Thinking of weeding, I will be bringing some stuff to the Hamfest on Sunday, I need to clear out a bit. I will have the odd microwave transverter, an HP8557 and an Altech noise figure meter might be of interest to those coming. The good thing about Hamfest is that it is wide ranging in an area with many microwave enthusiasts but not on the East coast where there appears to be a surplus of surplus.
 
Several things I will not bring as they raise too little cash nowadays - what does one do with VHF valve linears these days for example? They are practically obsolete for powers below about 150W and running more than 200W from most homes disturbs nearby electronic equipment. There must be thousands in cupboards, under beds, in sheds and in garages all over the country. I appear to have several and doubt I am untypical. Too heavy to take and bring back.
 
Mike

--
Scanned by iCritical.



Re: beam and coax

G3RIR <g3rir@...>
 

Ecoflex 15 is very easy to handle and the loss is very nearly as good as
LDF450. You will probably need a mast head pre-amp unless your coax run is
very short.

I use a 35 ele Tonna but I suggest you get something a big bigger and more
robust.

Neil, G3RIR

-----Original Message-----
From: ukmicrowaves@yahoogroups.com [mailto:ukmicrowaves@yahoogroups.com] On
Behalf Of Chris
Sent: 08 August 2009 10:28
To: ukmicrowaves@yahoogroups.com
Subject: [ukmicrowaves] beam and coax

Hi I have just put the 23cm unit into my IC910 and I need some help with
what beam and coax to use on the 23cm band
thanks Chris GM4YLN



------------------------------------

Yahoo! Groups Links


beam and coax

Chris
 

Hi I have just put the 23cm unit into my IC910 and I need some help with what beam and coax to use on the 23cm band
thanks Chris GM4YLN


Re: Beacons and gardening

Bill <radio.m@...>
 

In message <4A7CBEF2.6030001@zen.co.uk>, David Wrigley
<zen130696@zen.co.uk> writes
 

Hi Andy

We've just bought a shredder to carry out a similar operation. I've
been really surpised at how much the bulk is reduced by shredding. It
will be interesting to see whether the chipped wood keeps down future
growth. It certainly removes any need to remove the cut branches from
site - recycling in action!
73 David G6GXK
On a similar note, I had a site that I looked after for a number of
years that had a wire mesh fence around it and razor wire on top. As
added security there were brambles growing on all sides. With only
minimal management the blackberries made good eating. Those coming
through the inside of the fence were kept away from Joe public and were
a perk of the job Just remember the old adage of "don't pick/eat
blackberries that grow below knee height!! :-)
--
Bill


Re: Beacons and gardening

David Wrigley <zen130696@...>
 

Hi Andy

We've just bought a shredder to carry out a similar operation. I've been really surpised at how much the bulk is reduced by shredding. It will be interesting to see whether the chipped wood keeps down future growth. It certainly removes any need to remove the cut branches from site - recycling in action!

73 David G6GXK




Andy Talbot wrote:

One disadvantge of maintaining a beacon on a remote site, is that
every so often you have to go up there and clear away the foliage...
This is what the Bell Hill site looked like after three years of
growth - see how the concrete cabin is buried in greenery - and the
fruits of our labours.
http://www.scrbg.org/beacon/ [scroll about two-thirds of the
way down, to the gardening session.]
Don't forget to visit the SCRBG stand at the FRARS Hamfest on Sunday.
http://www.frars.org.uk/cgi-bin/render.pl?pageid=1358
All donations to the upkeep of the beacons will be greatfully accepted
(but no gardening tools, please)
Andy
obo. www.scrbg.org
-


Re: FT-817 use with transverters

Andy Talbot <andy.g4jnt@...>
 

The input protection relay contacts are the wrong side of the detector
controlling it.

I drew the design up and initially laid-out the PCB like that,
realised the mistake and corrected things on the finished module. But
then, unfortunately, sent the old diagrams for publication. Just one
reader spotted the error - almost immediately.

Andy
www.g4jnt.com



2009/8/6 Paul Whatton <paul@g4dcv.co.uk>:



Scratching my had looking for the deliberate mistake.... The values seem
to be for a 6dB rather than a 5dB attenuator as described in the text
but I bet that's not it?

Paul



The interface was published in RadCom around about 1994. Can't check
which edition at the moment (at work) but will do so this evening.
Incidently there's an error in the circuit diagram as published -
kudos to the first to spot it.

Andy
www.g4jnt.com


Beacons and gardening

Andy Talbot <andy.g4jnt@...>
 

One disadvantge of maintaining a beacon on a remote site, is that
every so often you have to go up there and clear away the foliage...
This is what the Bell Hill site looked like after three years of
growth - see how the concrete cabin is buried in greenery - and the
fruits of our labours.
http://www.scrbg.org/beacon/ [scroll about two-thirds of the
way down, to the gardening session.]

Don't forget to visit the SCRBG stand at the FRARS Hamfest on Sunday.
http://www.frars.org.uk/cgi-bin/render.pl?pageid=1358

All donations to the upkeep of the beacons will be greatfully accepted
(but no gardening tools, please)

Andy
obo. www.scrbg.org