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Reducing output signal   Message List  
Reply | Forward Message #5577 of 6095 |
Re:Reducing output signal

This is of interest to me, as I need to move my transmitter for a few
weeks while decorating the studio.
I have a 7 metre coax extension lead. Will this cause much loss to my
transmitter power?

Cheers,
Grant



--
88.4FM The Cheese - Hits Of The 80s, 90s and Today!
www.thecheese.co.nz <http://www.thecheese.co.nz/>

P.O Box 43214, Wainuiomata 5014, New Zealand
studio@... <mailto:studio@...>
Thu Feb 14, 2008 9:46 am

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grantthoms
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Forward 		Message #5577 of 6095 |
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Heya guys, Anybody got any bright ideas on how to reduce the signal coming out of the back of the transmitter? We have a one watt transmitter but wish to... 		Michael Rowse
valdusradio
Offline Send Email 		Feb 13, 2008
5:33 pm

Probably the cheapest/way to reduce power is to add attentuation to the aerial lead. Add length to the cable... not sure of exact figures but adding 10 metres...
Geoff Barkman
Mad_Milkie
Offline Send Email 		Feb 13, 2008
8:13 pm

Geoff's right. The easiest way to reduce power is to use more coax. The data is in the back of the Dick Smith catalog. If I remember correctly the spec for...
John Peterson
johnfp3
Offline Send Email 		Feb 13, 2008
8:40 pm

Speaking of 2.4GHz spectrum. I just hooked up some 600mW Wi-Fi PCI cards to have a look at the 2.4GHz spectrum in Invercargill. The amount of wireless LANs is...
Gavin Stephens
kiwi_rock_24
Offline Send Email 		Feb 14, 2008
12:05 am

This is of interest to me, as I need to move my transmitter for a few weeks while decorating the studio. I have a 7 metre coax extension lead. Will this cause...
88.4 FM The Cheese
grantthoms
Offline Send Email 		Feb 14, 2008
9:46 am

Hello Grant, Will be a little loss in TX power... now to get my calculator out :))) If your TX is out putting 500mw @ 88.4 MHZ, SWR of 1:1 at 7 meters of coax ...
Johnno
j_larsen2006
Offline Send Email 		Feb 14, 2008
11:01 am

That's great Johnno.. Thanks for the info :) Cheers, Grant ... of coax...
grantthoms
Offline Send Email 		Feb 15, 2008
9:22 am

Hey Johnno, Studying your figures, it seems that RG58A has a loss of 13mW per metre? So would I be right in saying to get a 1 watt TX down to approx. 300mW or...
Michael Rowse
valdusradio
Offline Send Email 		Feb 14, 2008
5:57 pm

The figures are based on the Freq Range, SWR ratio (ie: 1:1) and the cable that is being used... If we use 88.4 mhz, 1 Watt, SWR 1:1 and using RG58A = 39...
Johnno
j_larsen2006
Offline Send Email 		Feb 14, 2008
7:34 pm

I've been watching all the suggestions for reducing power and that is a simple and practical way of dealing with it. However if you have the schematic diagram...
averagesteward
Offline Send Email 		Feb 14, 2008
7:40 pm

Unfortunately it's not as simple as working it out to a mW per meter. That's why things are done in dB. For example, driving a coax cable with a known loss of...
Gavin Stephens
kiwi_rock_24
Offline Send Email 		Feb 15, 2008
1:13 am

You can make yourself a simple T attenuator with a loss of about 5.2dB Close to that value will suffice as its not exactly critical. Build it in a tin box with...
Keith
wantok.geo
Offline Send Email 		Feb 15, 2008
1:25 am

By the way, it's 500mW eirp, output from the antenna... Cheers Dean Groove 107.7FM PO Box 10 989 Wellington Ph 381 4766 (381GROOVE) Fax 381 4755 Mob 021-457...
Groove 107.7FM
groove_crew
Offline Send Email 		Feb 15, 2008
6:34 am

Thanks for those, Gavin. D. ... From: Gavin Stephens To: LPFM_Radio@... Sent: Friday, February 15, 2008 3:10 PM Subject: Re: [LPFM] Re:Reducing...
Groove 107.7FM
groove_crew
Offline Send Email 		Feb 15, 2008
6:57 am

That coax cable one is handy but I've just finally noticed the power budget one isn't right. It asks for dBm on a lot of things and provides answers in dB when...
Gavin Stephens
kiwi_rock_24
Offline Send Email 		Feb 15, 2008
11:42 am

... Reduce the drive to the final output - usually by reducing the voltage supplied to it. The final will last longer and run cooler....
wireless.radio
Offline Send Email 		Feb 16, 2008
6:43 am

Hey guys, I just realised that I never actually thanked everyone for their ideas on reducing the signal output. Shame on me. So....thanks everyone! We have...
Michael Rowse
valdusradio
Offline Send Email 		Mar 1, 2008
9:51 pm
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