Discussion:
[G0MGX] A new approach to 13cm
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G0MGX via rec.radio.amateur.moderated Admin
2018-03-22 15:11:41 UTC
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G0MGX In the Shack

///////////////////////////////////////////
A new approach to 13cm

Posted: 21 Mar 2018 09:35 AM PDT
http://g0mgx.blogspot.com/2018/03/a-new-approach-to-13cm.html

Well,

You may recall back here where I built a 13cm capability. I've decided to
go about it a different way.

Instead of sending lots of RF up lossy coax with a fixed station
arrangement, I'm going to generate less RF but right next to the
antennamabob and make the whole setup portable.

So here we have 13cm take 2:


In here we have the transverter, sequencer, the VLNA, a SMA relay and
driver, plus this PA will also fit; but I dont have the PA yet. The wonky
board you can see is a FET driver to switch the PA bias supply on during
TX; that will be mounted on top of the PA once I have it here.

I've hooked up my XL Microwave power meter to the output of the Transverter
via a 40dB attenuator and I am measuring:


about 32.5 dBm so close to 2 watts - exactly on the money of the
transverter spec.

The PA needs a 1W drive so I will have to attenuate the TX signal by 3dB to
get that correct.

Good, egh?
Brian Morrison
2018-03-22 15:47:19 UTC
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On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal by
3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the PA
drive by 3dB and waste less heat or even reduce the current drain to
boot.
--
Brian Morrison
A. non Eyemouse
2018-03-22 16:40:48 UTC
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Post by Brian Morrison
On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal by
3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the PA
drive by 3dB and waste less heat or even reduce the current drain to
boot.
It must be the Rolly-Roycy way of doing things. Plenty of power to burn. ;-)
--
Mouse.
Where Morse meets House.
mm0fmf
2018-03-22 17:44:51 UTC
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Post by Brian Morrison
On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal by
3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the PA
drive by 3dB and waste less heat or even reduce the current drain to
boot.
Not as wasteful as turning 1W into heat which is what he is going to do.
Brian Morrison
2018-03-22 18:24:21 UTC
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On Thu, 22 Mar 2018 17:44:51 +0000
Post by mm0fmf
Post by Brian Morrison
On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal
by 3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the
PA drive by 3dB and waste less heat or even reduce the current
drain to boot.
Not as wasteful as turning 1W into heat which is what he is going to do.
Indeed, I misread the original.
--
Brian Morrison
Stephen Thomas Cole
2018-03-22 18:42:36 UTC
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Post by Brian Morrison
On Thu, 22 Mar 2018 17:44:51 +0000
Post by mm0fmf
Post by Brian Morrison
On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal
by 3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the
PA drive by 3dB and waste less heat or even reduce the current
drain to boot.
Not as wasteful as turning 1W into heat which is what he is going to do.
Indeed, I misread the original.
FURIOUS backpedal.

LRN 2 LOGARITHMIC. HTH. HAND. YFI.
--
STC / M0TEY /
http://twitter.com/ukradioamateur
Brian Morrison
2018-03-22 19:16:30 UTC
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On 22 Mar 2018 18:42:36 GMT
Post by Stephen Thomas Cole
Post by Brian Morrison
Indeed, I misread the original.
FURIOUS backpedal.
My mental maths was inverted, I admitted the error.

Never been perfect...
--
Brian Morrison
Stephen Thomas Cole
2018-03-22 19:56:47 UTC
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Post by Brian Morrison
Never been perfect...
Ain't that the truth!
--
STC / M0TEY /
http://twitter.com/ukradioamateur
Brian Morrison
2018-03-23 10:56:41 UTC
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On 22 Mar 2018 19:56:47 GMT
Post by Stephen Thomas Cole
Post by Brian Morrison
Never been perfect...
Ain't that the truth!
I've looked in the mirror often enough to know that, others may not
have.
--
Brian Morrison
Jim.GM4DHJ ...
2018-03-23 11:15:42 UTC
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Post by Brian Morrison
On 22 Mar 2018 19:56:47 GMT
Post by Stephen Thomas Cole
Post by Brian Morrison
Never been perfect...
Ain't that the truth!
I've looked in the mirror often enough to know that, others may not
have.
some people like brian reay don't have a reflection ....tee hee
Spike
2018-03-23 10:55:15 UTC
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Post by Brian Morrison
Post by Brian Morrison
Indeed, I misread the original.
My mental maths was inverted, I admitted the error.
Never been perfect...
I think the real error here is the OP's. If he's going to go portable,
presumably including carrying stuff to a remote location, he needs to
rethink his paradigm, power and weight both being key factors in such a
situation. To add extra weight (an attenuator) in order to discard some
of the power from a source that itself has a weight penalty detracts
from the portability aspect of the station.

If it's just a technology demonstration run in order to find bugs and
provide information on trade-offs, that would be a different
consideration, but he didn't say if this was so.
--
Spike

"RSGBTech is meant for everyone", or so the RSGB says. The group is
moderated 'to
ensure that the questions are on topic', but the group's own admissions
policy mention
(a pre-) 'vet', 'known', 'trouble', and 'maker', but not the vetting
policy! None of these are
'moderation' issues and none are mentioned in the RSGB's Guidelines.....
Brian Morrison
2018-03-23 11:01:28 UTC
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On Fri, 23 Mar 2018 10:55:15 +0000
Post by Spike
To add extra weight (an attenuator) in order to discard some
of the power from a source that itself has a weight penalty detracts
from the portability aspect of the station.
I recall the calculation for a naval aircraft for use from an aircraft
carrier, saving 1lb in structure weight resulted in a total saving of
7lbs in take-off weight. This isn't quite at that level but still,
humping heavy stuff up the scenery is not without its downside.
--
Brian Morrison
Spike
2018-03-23 11:16:10 UTC
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Post by Brian Morrison
Post by Spike
To add extra weight (an attenuator) in order to discard some
of the power from a source that itself has a weight penalty detracts
from the portability aspect of the station.
I recall the calculation for a naval aircraft for use from an aircraft
carrier, saving 1lb in structure weight resulted in a total saving of
7lbs in take-off weight.
Rocketry is much the same. During the Apollo era, huge exercises were
undertaken to save a pound or two of LEM weight. I believe the camera
was 'de-scoped' and reinstated several times, finally the decision was
made from a publicity angle, thank goodness,

At one time I knew the chap that helped design the camera storage
system. Being sort of impish, he labelled the drawings 'Modular
Equipment Storage System', and it was a long time before NASA tumbled to
this and renamed it the 'Modular Equipment Storage Assembly'. Apollo
11's LEM flew with far more signatures than Richard Nixon's on it.
Post by Brian Morrison
This isn't quite at that level but still,
humping heavy stuff up the scenery is not without its downside.
That's why it's important to think about these trade-offs., Hopefully,
as I said, the OP's exercise is more suck-it-and-see than finished gear.
--
Spike

"RSGBTech is meant for everyone", or so the RSGB says. The group is
moderated 'to
ensure that the questions are on topic', but the group's own admissions
policy mention
(a pre-) 'vet', 'known', 'trouble', and 'maker', but not the vetting
policy! None of these are
'moderation' issues and none are mentioned in the RSGB's Guidelines.....
Jim.GM4DHJ ...
2018-03-23 11:23:21 UTC
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Post by Spike
Post by Brian Morrison
Post by Brian Morrison
Indeed, I misread the original.
My mental maths was inverted, I admitted the error.
Never been perfect...
I think the real error here is the OP's. If he's going to go portable,
presumably including carrying stuff to a remote location, he needs to
rethink his paradigm, power and weight both being key factors in such a
situation. To add extra weight (an attenuator) in order to discard some of
the power from a source that itself has a weight penalty detracts from the
portability aspect of the station.
If it's just a technology demonstration run in order to find bugs and
provide information on trade-offs, that would be a different
consideration, but he didn't say if this was so.
I used to haul a car battery, HB9CV and a liner 2 up Tomtain in the
70's....to chagrin of people in the near of Glasgow .......and recently an
HB9CV and an FT817ND up Bynehill........waste of a nice day .......handy for
my trailer though .....


https://www.google.co.uk/maps/@55.2175803,-4.8573225,1166m/data=!3m1!1e3
mm0fmf
2018-03-22 18:49:43 UTC
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Post by Brian Morrison
On Thu, 22 Mar 2018 17:44:51 +0000
Post by mm0fmf
Post by Brian Morrison
On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal
by 3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the
PA drive by 3dB and waste less heat or even reduce the current
drain to boot.
Not as wasteful as turning 1W into heat which is what he is going to do.
Indeed, I misread the original.
It's a simple pragmatic solution to his problem. Gone are the days when
generating any power on these bands was hard and expensive so you didn't
want to waste anything.
Brian Morrison
2018-03-22 19:15:20 UTC
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On Thu, 22 Mar 2018 18:49:43 +0000
Post by mm0fmf
Post by Brian Morrison
On Thu, 22 Mar 2018 17:44:51 +0000
Post by mm0fmf
Post by Brian Morrison
On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal
by 3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the
PA drive by 3dB and waste less heat or even reduce the current
drain to boot.
Not as wasteful as turning 1W into heat which is what he is going to do.
Indeed, I misread the original.
It's a simple pragmatic solution to his problem. Gone are the days
when generating any power on these bands was hard and expensive so
you didn't want to waste anything.
Maybe, but if he's thinking of running portable then saving power helps
with portable power usage. Heat is always the enemy of reliability too.
--
Brian Morrison
mm0fmf
2018-03-22 19:37:00 UTC
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Post by Brian Morrison
On Thu, 22 Mar 2018 18:49:43 +0000
Post by mm0fmf
Post by Brian Morrison
On Thu, 22 Mar 2018 17:44:51 +0000
Post by mm0fmf
Post by Brian Morrison
On Thu, 22 Mar 2018 11:11:41 EDT
Post by G0MGX via rec.radio.amateur.moderated Admin
The PA needs a 1W drive so I will have to attenuate the TX signal
by 3dB to get that correct
Turning 0.5W into heat seems wasteful, surely better to reduce the
PA drive by 3dB and waste less heat or even reduce the current
drain to boot.
Not as wasteful as turning 1W into heat which is what he is going to do.
Indeed, I misread the original.
It's a simple pragmatic solution to his problem. Gone are the days
when generating any power on these bands was hard and expensive so
you didn't want to waste anything.
Maybe, but if he's thinking of running portable then saving power helps
with portable power usage. Heat is always the enemy of reliability too.
There's portable and there's portable. From the pictures it's not going
be carried far. I carry my 13cms gear up to the top of mountains along
with the batteries. I'm not carrying something so I can waste power
having carried it for miles!
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