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Boosting signal reception


#1

In reply to 2E0NHM:

Do i need to buy one just so i can boost the reception ??

Normally only for upper VHF and UHF. Depends of course from were the noise/interference is coming.

73, Jaakko OH7BF/F5VGL


#2

In reply to 2E0NHM:

There is a simple test, Nigel.

Tune to a clear channel, turn up the AF gain. Unplug the antenna, if the noise in the speaker drops then a pre-amp will not help you as it will amplify the noise by the same amount that it amplifies signals. If the noise in the speaker doesn’t change then a pre-amp will help you, but that is rare on HF nowadays!

73

Brian G8ADD


#3

In reply to G8ADD:

Another thought. I’ve seen many operators using the RF gain control full on. For weak signals, turn off the AGC and gradually back off the RF gain. The noise rolls off sooner than the desired signal. Keep a steady hand on the gain control, though, as a sudden loud signal will leave a truly memorable dent in the side of your skull where the headphones launched themselves across the room.

73 and climb safely,

Elliott, K6ILM


#4

In reply to 2E0NHM:

If only it were so easy…

You want a bigger aerial, or a quieter environment. Or both. You may not be able to do much about the 1st item. You may be able to more about the second using suppression and nulling techniques.

In HF reception, the sky noise will be huge, you can see this by the way the noise rises when you connect an aerial. With a modern receiver like an FT1000MP, the front end noise figure will be negligible compared to the sky noise, it’s already working well.

A preamp wont help as preamp will amplify the noise and signal equally and there is no net gain.Where HF preamps do help is with old receivers (AR88 etc.) where the gain drops off above 20MHz.

If you can’t get more signal with a bigger antenna and you can’t reduce the local noise contribution at the antenna then all you can do is reduce the noise contribution to the signal by reducing the bandwidth in use by using a narrower mode where there are more Watts/Hz.

Andy
MM0FMF


#5

In reply to 2E0NHM:

I think what you are looking for is low noise paint, sometimes referred to as Dragon Teeth.

The only real answer is to move to a low noise area (somewhere remote from the urbane sprawl) and a property with loads of land, which is why so many of us like to do SOTA and find low noise take-offs on mountain tops.

If you find what you are looking for you may want to try looking for the Holy Grail next.

Good luck on your quest.

Steve GW7AAV

Welcome to The Quest for Low Signal to Noise Ratio.

You are standing by a transformer. There is the sound of buzzing and the smell of ozone in the air.

Next?

E

:East

You walk East and meet three witches.

_


#6

In reply to GW7AAV:

You walk East and meet three witches.

Impale first witch with roach pole

You left your roach pole on G/SP-013


#7

In reply to G4AFI:

First witch is Granny Weatherwax…

73

Brian G8ADD


#8

In reply to G8ADD:

First witch is Granny Weatherwax…

What do you want me to do with “First witch”?

… good grief, that was a long time ago … the “maze of twisty passages, all different” was always good fun …

73
John GM8OTI


#9

In reply to GM8OTI:

I’ve played the original Crowther & Woods FORTRAN version on a PDP-10. Actually DECSYSTEM-20 but who here knows the difference :slight_smile:

Xyzzy
Nothing happens.

:slight_smile:

Andy
MM0FMF


#10

In reply to MM0FMF:

I was going to raise you a PDP-7

http://www.soemtron.org/pdp7.html

but it wasn’t Adventure (the colossal cave) - it was Spacewar, which had two orbiting suns that you had to pilot your ship around, chasing the baddy. It was great fun, you could use the PDP-7 switches to do things like turn on and off conservation of angular momentum, even gravity, etc!

I could have sworn Adventure was pre 1975, but various web articles say not, and the authors should know.

Throw age at GM8OTI
GM8OTI’s memory gets worse and worse

73
John GM8OTI


#11

In reply to MM0FMF:

I’ve played the original Crowther & Woods FORTRAN version on a
PDP-10. Actually DECSYSTEM-20 but who here knows the difference :slight_smile:

Xyzzy
Nothing happens.

I played it on DEC System-10’s and on PDP-11’s

I managed to get carried off into the sunset by a band of happy Elves.

Fee Fie Foe Foo

Colin G8TMV


#12

In reply to G8TMV:

I have to admit John out-vintages me with PDP-7 experience.

So many memories come flooding back thinking of the fun we undergrads had in the never ending battle to gain more resource and access time to the assorted machines. PDP-10s, PDP-11s, Amdahls etc… Strangely people would crawl through a sewer filled with broken glass for more access to the 10s and 11s. But the 470 was treated with contempt unless it was the only game in town.

Andy
MM0FMF


#13

In reply to MM0FMF: “I have to admit John out-vintages me with PDP-7 experience.”

How about “I’m afraid the operator dropped your cards. We’ll try running your program again tomorrow.”

Most people reading this will have no idea what it means!

73
Ken


#14

In reply to GI4FLG:

Ah, memories of an IBM Model 29 keypunch :slight_smile:

One of things I regret now is having a clear out when I moved house 11 years ago. I had kept a number of computer memorabilia and I dumped them when rationalising the stuff to move. I still have no need for them nor are they valuable. But I would like a punched card. Or a complete deck of cards for a program complete with JCL cards.

Things thrown out:

A blank punched card
A punched card saying "I am a punched card"
A punched tape for an Data General Nova (one pass of the Algol compiler)
An 8in floppy disk
All my 5.25in floppies (low and high density)
All my 3in Amstrad disks
A DECtape reel
A 1600bpi 9 track tape
An RL02 data cartridge

Andy
MM0FMF


#15

In reply to MM0FMF:
This topic ought to be renamed… computing nostalgia… or something similar, hi!
My experience goes back to using Autocode on a Ferranti Sirius back in 1961-62; some 30,000 valves and I/O using a Creed 5-channel papertape… !
73 de Ken


#16

In reply to MM0FMF:

But I would like a punched card. Or a
complete deck of cards for a program complete with JCL cards.

I have some punched cards somewhere, but I won’t give up a complete deck! I’ll bring you one or two if I can dig them out.

73
John GM8OTI