dish building


Chris Ruddy MM0KOS
 

Hi All

Has anyone here tried to build ther own dish from fibreglass, i have
all the data to build the dish but dont want to build it from mesh as
it will probably be used /p at times and be thrown about a bit,
storage is a problem and with metal in the weather conditions in
Scotland.
im planning on a 4m dish first then maybe a 6m dish if all goes ok
and will either be an 8 or 4 petal dish, im thinking of using
fibreglass rod (4 or 6mm) to strengthen from the back with 4 alloy
15mm square sections to support the septum (or less if i use a patch
feed) and help keep the shape of the dish from the back. and a piece
of 10mm ally plate that all the 15mm box sections will bolt or have
some way of being inserted on to it
For the mould im using an insulating type foam board that can be
roughed down with a wire brush then sanded to a finer finish.
I have a dish stand suitable for the project that i hope to build
into a small trailer that will keep all the parts together when
dissasembled for transporting
Has anyone any other ideas how i could strenthen or ideas they have
used on their own project or anything they feel they could chip in for
advice

Thanks Chris MM0KOS


Mike Willis <m.j.willis@...>
 

A 6m dish portable! In Scotland! Please no.

I would look around for a surplus one, dishes of that size are generally far too big for most amateurs and tend to be available for the price of taking them away. Building one from fibreglass is a major undertaking because of the wind loading. You could cover a mesh dish with fibreglass. Good luck.

Mike

mm0kos wrote:


Hi All

Has anyone here tried to build ther own dish from fibreglass, i have
all the data to build the dish but dont want to build it from mesh as
it will probably be used /p at times and be thrown about a bit,
storage is a problem and with metal in the weather conditions in
Scotland.
im planning on a 4m dish first then maybe a 6m dish if all goes ok
and will either be an 8 or 4 petal dish, im thinking of using
fibreglass rod (4 or 6mm) to strengthen from the back with 4 alloy
15mm square sections to support the septum (or less if i use a patch
feed) and help keep the shape of the dish from the back. and a piece
of 10mm ally plate that all the 15mm box sections will bolt or have
some way of being inserted on to it
For the mould im using an insulating type foam board that can be
roughed down with a wire brush then sanded to a finer finish.
I have a dish stand suitable for the project that i hope to build
into a small trailer that will keep all the parts together when
dissasembled for transporting
Has anyone any other ideas how i could strenthen or ideas they have
used on their own project or anything they feel they could chip in for
advice

Thanks Chris MM0KOS



John Randall <m0els@...>
 

Chris, Its easier to purchase a kit from a place called rf hamdesigns
 
73
John

mm0kos wrote:
Hi All

Has anyone here tried to build ther own dish from fibreglass, i have
all the data to build the dish but dont want to build it from mesh as
it will probably be used /p at times and be thrown about a bit,
storage is a problem and with metal in the weather conditions in
Scotland.
im planning on a 4m dish first then maybe a 6m dish if all goes ok
and will either be an 8 or 4 petal dish, im thinking of using
fibreglass rod (4 or 6mm) to strengthen from the back with 4 alloy
15mm square sections to support the septum (or less if i use a patch
feed) and help keep the shape of the dish from the back. and a piece
of 10mm ally plate that all the 15mm box sections will bolt or have
some way of being inserted on to it
For the mould im using an insulating type foam board that can be
roughed down with a wire brush then sanded to a finer finish.
I have a dish stand suitable for the project that i hope to build
into a small trailer that will keep all the parts together when
dissasembled for transporting
Has anyone any other ideas how i could strenthen or ideas they have
used on their own project or anything they feel they could chip in for
advice

Thanks Chris MM0KOS




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Dave G4RGK .
 



Chris,

Making a dish using Fibreglass is real hard work and it will end up extremely heavy. Last year I made a 4m dish
and mount for around 200 quid using the stressed principle promoted for many years by K2RIW and K2UYH - took
about six weeks of evenings. If you decide to go this route, email me off list.

73 Dave G4RGK
 


mm0kos wrote:
Hi All

Has anyone here tried to build ther own dish from fibreglass, i have
all the data to build the dish but dont want to build it from mesh as
it will probably be used /p at times and be thrown about a bit,
storage is a problem and with metal in the weather conditions in
Scotland.
im planning on a 4m dish first then maybe a 6m dish if all goes ok
and will either be an 8 or 4 petal dish, im thinking of using
fibreglass rod (4 or 6mm) to strengthen from the back with 4 alloy
15mm square sections to support the septum (or less if i use a patch
feed) and help keep the shape of the dish from the back. and a piece
of 10mm ally plate that all the 15mm box sections will bolt or have
some way of being inserted on to it
For the mould im using an insulating type foam board that can be
roughed down with a wire brush then sanded to a finer finish.
I have a dish stand suitable for the project that i hope to build
into a small trailer that will keep all the parts together when
dissasembled for transporting
Has anyone any other ideas how i could strenthen or ideas they have
used on their own project or anything they feel they could chip in for
advice

Thanks Chris MM0KOS


SAM JEWELL
 

At Weinheim, the OK guys introduced a series of dish kits. These (reportedly) have laser cut ribs and are currently available up to 2.4m diameter. I believe that bigger ones are on the way. Expect to see adverts in Dubus etc sometime soon. The pricing looked pretty good as well. Rather than report the wrong numbers, I'd prefer to wait and see what appears in their adverts.
Certainly worth a look.

73 de Sam


John Randall wrote:

Chris, Its easier to purchase a kit from a place called rf hamdesigns
 
73
John

mm0kos co.uk> wrote:
Hi All

Has anyone here tried to build ther own dish from fibreglass, i have
all the data to build the dish but dont want to build it from mesh as
it will probably be used /p at times and be thrown about a bit,
storage is a problem and with metal in the weather conditions in
Scotland.
im planning on a 4m dish first then maybe a 6m dish if all goes ok
and will either be an 8 or 4 petal dish, im thinking of using
fibreglass rod (4 or 6mm) to strengthen from the back with 4 alloy
15mm square sections to support the septum (or less if i use a patch
feed) and help keep the shape of the dish from the back. and a piece
of 10mm ally plate that all the 15mm box sections will bolt or have
some way of being inserted on to it
For the mould im using an insulating type foam board that can be
roughed down with a wire brush then sanded to a finer finish.
I have a dish stand suitable for the project that i hope to build
into a small trailer that will keep all the parts together when
dissasembled for transporting
Has anyone any other ideas how i could strenthen or ideas they have
used on their own project or anything they feel they could chip in for
advice

Thanks Chris MM0KOS




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gm4plm <simon@...>
 

I have some pictures - will load them later for interest on here

prices were not so bad 500 eu for a 1,8 but this may have been a
show price!

OK1DFC was leading the sales so maybe worth folllwing his web page

he was also showing that up to 5m available - the 2,4m looked ok but
not as well built as the RFhamdesign ones and you also need to mesh
that too so extra cost

rgds

Simon DL4PLM/GM4PLM


--- In ukmicrowaves@yahoogroups.com, SAM JEWELL <jewell@...> wrote:

At Weinheim, the OK guys introduced a series of dish kits. These
(reportedly) have laser cut ribs and are currently available up to
2.4m diameter. I believe that bigger ones are on the way. Expect to
see adverts in Dubus etc sometime soon. The pricing looked pretty
good as well. Rather than report the wrong numbers, I'd prefer to
wait and see what appears in their adverts.
Certainly worth a look.

73 de Sam


John Randall <m0els@...> wrote:
Chris, Its easier to purchase a kit from a place called rf
hamdesigns

73
John

mm0kos <mm0kos@...> wrote:
Hi All

Has anyone here tried to build ther own dish from fibreglass, i
have
all the data to build the dish but dont want to build it from mesh
as
it will probably be used /p at times and be thrown about a bit,
storage is a problem and with metal in the weather conditions in
Scotland.
im planning on a 4m dish first then maybe a 6m dish if all goes ok
and will either be an 8 or 4 petal dish, im thinking of using
fibreglass rod (4 or 6mm) to strengthen from the back with 4 alloy
15mm square sections to support the septum (or less if i use a
patch
feed) and help keep the shape of the dish from the back. and a
piece
of 10mm ally plate that all the 15mm box sections will bolt or
have
some way of being inserted on to it
For the mould im using an insulating type foam board that can be
roughed down with a wire brush then sanded to a finer finish.
I have a dish stand suitable for the project that i hope to build
into a small trailer that will keep all the parts together when
dissasembled for transporting
Has anyone any other ideas how i could strenthen or ideas they
have
used on their own project or anything they feel they could chip in
for
advice

Thanks Chris MM0KOS







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


Chris Bartram <yahoo@...>
 

Parabolic <www.parabolic.se> have also made dish kits for at least a couple of
decades. An extended version of one of their 1.8m reflectors is currently
being used very successfully by SM5LE on 1.3GHz EME, and I think that Ben,
SM6CKU, who owns the company, is also looking at making bigger antennas.

I've looked in detail at making 2.4 - 3m dishes from fibreglass, and decided
against it, however that was for 10GHz EME. Although fireglass is tough, it
can be very heavy...

For 1.3/2.3GHz, I'd second Dave, 'RGK's, comments about stress dishes. They
really are very easy to make, and can provide very good results. I used one
(4m - surfaced with 1/2in chicken wire) briefly on 1.3GHz EME in the 1980s,
and was able to detect my CW echoes with about 100W at the feed and a 0.7dB
preamp.

I've been very tempted to try making an offset stress dish for 1.3/2.3, and I
think that Jonathan ON/G4KLX has also down that route.

Vy 73

Chris
GW4DGU


gm4plm <simon@...>
 

these are now loaded into the photo section under the album "weinheim
2007"



--- In ukmicrowaves@yahoogroups.com, "gm4plm" <simon@...> wrote:

I have some pictures - will load them later for interest on here

prices were not so bad 500 eu for a 1,8 but this may have been a
show price!

OK1DFC was leading the sales so maybe worth folllwing his web page

he was also showing that up to 5m available - the 2,4m looked ok
but
not as well built as the RFhamdesign ones and you also need to mesh
that too so extra cost

rgds

Simon DL4PLM/GM4PLM


--- In ukmicrowaves@yahoogroups.com, SAM JEWELL <jewell@> wrote:

At Weinheim, the OK guys introduced a series of dish kits. These
(reportedly) have laser cut ribs and are currently available up to
2.4m diameter. I believe that bigger ones are on the way. Expect to
see adverts in Dubus etc sometime soon. The pricing looked pretty
good as well. Rather than report the wrong numbers, I'd prefer to
wait and see what appears in their adverts.
Certainly worth a look.

73 de Sam


John Randall <m0els@> wrote:
Chris, Its easier to purchase a kit from a place called rf
hamdesigns

73
John

mm0kos <mm0kos@> wrote:
Hi All

Has anyone here tried to build ther own dish from fibreglass, i
have
all the data to build the dish but dont want to build it from
mesh
as
it will probably be used /p at times and be thrown about a bit,
storage is a problem and with metal in the weather conditions in
Scotland.
im planning on a 4m dish first then maybe a 6m dish if all goes
ok
and will either be an 8 or 4 petal dish, im thinking of using
fibreglass rod (4 or 6mm) to strengthen from the back with 4
alloy
15mm square sections to support the septum (or less if i use a
patch
feed) and help keep the shape of the dish from the back. and a
piece
of 10mm ally plate that all the 15mm box sections will bolt or
have
some way of being inserted on to it
For the mould im using an insulating type foam board that can be
roughed down with a wire brush then sanded to a finer finish.
I have a dish stand suitable for the project that i hope to build
into a small trailer that will keep all the parts together when
dissasembled for transporting
Has anyone any other ideas how i could strenthen or ideas they
have
used on their own project or anything they feel they could chip
in
for
advice

Thanks Chris MM0KOS







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


Ray <gm4cxm@...>
 

--- In ukmicrowaves@yahoogroups.com, "gm4plm" <simon@...> wrote:

these are now loaded into the photo section under the album "weinheim
2007"
Simon...my first thought was what a saloobrious location it was to
display these dishes!

73 Ray GM4CXM


gm4plm <simon@...>
 

stop taking the piss Ray!!!!!

:-))))

--- In ukmicrowaves@yahoogroups.com, "Ray" <gm4cxm@...> wrote:

--- In ukmicrowaves@yahoogroups.com, "gm4plm" <simon@> wrote:

these are now loaded into the photo section under the
album "weinheim
2007"
Simon...my first thought was what a saloobrious location it was to
display these dishes!

73 Ray GM4CXM


Chris Ruddy MM0KOS
 

HI all

Thanks to all who made comments and replied to my posting, here
goes for the replies, dont take them the wrong way, im glad you made
comments as it threw new ideas on the table

Mike- I dont see why not to have a 4 or 6m dish in GM land, why not,
there was a 6m dish here before but not sure if it was used or who
has it now, the whole point of the dish is the challenge of building
and using it with others local to me who are also interested in
amateur radio and have more of a sound knowledge than me in the
microwave bands and would like to have the use of it and for me to
learn a bit more in the hobby. Maybe our project is a bit on the big
side but i can say i tried and if i fail, i fail and if i succeed
then lets see what we can do with it on EME as it would be too
narrow for tropo, but we can always look at the 4x 35 ele for tropo.
On the portable side im looking at designing it so the dish can be
halved then folded again at the outer edge to make it smaller in the
transport position

John and Chris- Puchasing a kit sounds too easy, i like to build
things and see them working, dont get me wrong ive had my failures
like probably most in this group wether it be with building
amplifiers or circuits we hope will work at the end and for some
strange or unexpected reason something goes horribly wrong but we
live to tell the tale and try again. Or we could go for the ready
made black box which is a no no for me

Simon- The 1.8m dish for 500eu, maybe a bit on the steep side,
family comes first in my house ( with my YL, you would agree with
that comment HI). I have 2x 1,8m dishes here 1 has full elevation
and rotation just needs setup in the garden and cant get the time to
do it sadly but i will get round to it some day after i complete the
homebrew amplifier for 23cm and winter that started last year has
gone

Dave- 4m dish with stressed mesh seems maybe a good idea and
strongly taken on board with taking into conciderations from
everyone about the weight of the fibreglass structure. I have a
mount that would support a 4m dish here in the garden but its
getting round to getting the strimmer round the weeds to see if its
still there or the neighbours have scrapped it, I have nearly enough
13mm square section ally that could be used for the ribs and a
friend who could do the neccessary welding to do any othere bits we
need and can get parts milled out also. Mesh size would be the only
problem when getting to the 10ghz side of things, maybe a double
layer of fine mesh?

73 for now Chris

Thanks again


g0ewn191 <g0ewn191@...>
 

Hi Chris--I was interested in the thread on dishes and the various
replies you received as I hope to try EME sometime---hopefully next
year. I also have been wondering whether to build, buy a kit, look for
a surplus dish or buy a petalised TVRO dish. A lot depends on the
following.

1. The frequency or frequencies you intend to use.

2. Is the dish mainly for tropo or EME.

If you are mainly interested in the lower bands---23 & 13cms then 4m
is a good size. However a dish this size made from GRP would be quite
an undertaking compared with more common stressed dish made from
alloy. A solid dish this size would be subject to some very strong
forces even in light winds. Reading your post I got the impression
(might be wrong) that your intended use is for a tropo system. If this
is the case you might be interested in using a plane parabaloid fed
with a twin double quad feed. If this sounds gobledigook look up an
article by G4CYA, Chris Otley. I had some input to this design though
Chris built the working unit and wrote up his work on his website. If
your intended use is tropo this antenna has a number of advantages:
ease of contruction and wider horizontal beamwidth. Look at the
article--it should be easy to scale for 4m and could easily be made
sectional for transport.

If you are mainly interested in the higher bands things are more of a
problem as the profile of the dish becomes more important. Upto 6cms a
dish with fine mesh would seem a good bet. Along with the info you
have already been supplied with, check out SAMI Dishes. This company
do a very nice 3m dish for around $700 (£350) though shipping and
import might double the cost. ( Still cheaper than 3m RF Hamdesign I
seem to remember). I'm not aware of a UK supplier of similar dishes.

At 10ghz or above 1.8 and 2.4m sectional dishes are available--best
price currently around £140 (2.4m) from a company in N. Shields. Most
commercial dishes have f/d ratios around .4 making them suitable for
EME---making your own dish would give you freedom to design the f/d to
match other feeds.

Good luck with your project--whichever route you choose. Please write
something up for Scatterpoint when you have an operational unit and
let us all know about it. 73s and best wishes Gordon G0EWN


Mike Willis <m.j.willis@...>
 

The reason for my comment on the 6m dish in GM portable was to do with the practicality of it when the weather is bad - moderately strong winds could easily produce several tonnes of wind loading on a 6m solid dish. On decent site, the wind could be strong, that is why so many wind farms are being built in Scotland.

A 6m dish is very large to transport, even if folded in two. Fixed, by all means if you have the space. Personally, I would go the mesh route initially simply to reduce the wind loading.

Mike






Mike- I dont see why not to have a 4 or 6m dish in GM land, why not,
there was a 6m dish here before but not sure if it was used or who
has it now, the whole point of the dish is the challenge of building
and using it with others local to me who are also interested in
amateur radio and have more of a sound knowledge than me in the
microwave bands and would like to have the use of it and for me to
learn a bit more in the hobby. Maybe our project is a bit on the big
side but i can say i tried and if i fail, i fail and if i succeed
then lets see what we can do with it on EME as it would be too
narrow for tropo, but we can always look at the 4x 35 ele for tropo.
On the portable side im looking at designing it so the dish can be
halved then folded again at the outer edge to make it smaller in the
transport position


Chris Ruddy MM0KOS
 

Hi all

Thanks again for the replies, the dish would be used for EME and
its not just for me, there is a group of us with a good mixture of
bands and knowledge on HF, VHF, SHF all the way to laser. The main
reason for asking was to get the up and down side of others
experience in building or having bigger dishes, now i can see or
best think, the best way to go is a stressed mesh dish but this
depends on the location we choose for /p work and how exposed it is
to the WX in GM. We intend to use it from 23cm upwards to 10ghz for
EME but we also have beams for 23cm for tropo use, maybe at a later
date we will consider higher bands.
I am just about capable of 23cm EME if I get my finger out and
complete the 2x GI7B amplifier, build the dish i have here and mount
the allready built septum on it.
I have also looked at patch feeds for multi band purposes and have
build one for 23cm but dont know how successful it will be, i need
to get a spectrum analyser on it and have a fiddle to see if it will
perform, if not ill try again and then try other bands on it too.
With regards to scatter point i would be more than happy to write a
small piece for you on how we get on with the project but may be a
little time before we get fully going and hope to have some sort of
web page on line soon with pages showing the current projects that
we are working on justnow

Thanks Gordon and all the others again 73 have a nice September
weekend




--- In ukmicrowaves@yahoogroups.com, "g0ewn191" <g0ewn191@...> wrote:

Hi Chris--I was interested in the thread on dishes and the various
replies you received as I hope to try EME sometime---hopefully next
year. I also have been wondering whether to build, buy a kit, look
for
a surplus dish or buy a petalised TVRO dish. A lot depends on the
following.

1. The frequency or frequencies you intend to use.

2. Is the dish mainly for tropo or EME.

If you are mainly interested in the lower bands---23 & 13cms then
4m
is a good size. However a dish this size made from GRP would be
quite
an undertaking compared with more common stressed dish made from
alloy. A solid dish this size would be subject to some very strong
forces even in light winds. Reading your post I got the impression
(might be wrong) that your intended use is for a tropo system. If
this
is the case you might be interested in using a plane parabaloid fed
with a twin double quad feed. If this sounds gobledigook look up an
article by G4CYA, Chris Otley. I had some input to this design
though
Chris built the working unit and wrote up his work on his website.
If
your intended use is tropo this antenna has a number of advantages:
ease of contruction and wider horizontal beamwidth. Look at the
article--it should be easy to scale for 4m and could easily be made
sectional for transport.

If you are mainly interested in the higher bands things are more
of a
problem as the profile of the dish becomes more important. Upto
6cms a
dish with fine mesh would seem a good bet. Along with the info you
have already been supplied with, check out SAMI Dishes. This
company
do a very nice 3m dish for around $700 (£350) though shipping and
import might double the cost. ( Still cheaper than 3m RF Hamdesign
I
seem to remember). I'm not aware of a UK supplier of similar
dishes.

At 10ghz or above 1.8 and 2.4m sectional dishes are available--best
price currently around £140 (2.4m) from a company in N. Shields.
Most
commercial dishes have f/d ratios around .4 making them suitable
for
EME---making your own dish would give you freedom to design the
f/d to
match other feeds.

Good luck with your project--whichever route you choose. Please
write
something up for Scatterpoint when you have an operational unit and
let us all know about it. 73s and best wishes Gordon G0EWN