Jim, First add all the System Gains (SG)in dbW measurements, from that figure you then subtract all your Sytem Losses (SL)in dbW, the result equals your ERP in dbW. Convert the ERP in dbW back to ERP in Watts.
Before you start adding the SG you must convert your Tx output pwr. from Watts to dbW. (ie 50w=17.0dbW) I use a Conversion Table that is included in some old Rptr. coord, papers, however you should be able to find a conversion table or the mathematical(sp?) formula on Google or on one of the Rptr. Bldr. site pages. Therefore the following example: 1. 50w Tx out=17.0dbW + ant. gain 9.2 dbW = Tot. SG 26.2dbW 2. Ant. FL lgth. /100 x loss per 100' at you freq band = Tot/FL loss in db. (50 /100x1.04 = .52dbW (1/2"LDF @ 450mhza=1.04db/100'). 3. Duplexer insertion loss = 1.5 dbW 4. Other losses = 0.0dbW 5. Tot. SL (.52+1.5) = 2.02dbW 6. Tot. SG (26.2) - Tot. SL (2.02) = Tot. ERP in dbW (24.18dbW) 7. Convert ERP in dbW back to ERP in Watts (24.18 = 250+ Watts ERP. Note: Some interpolation of the tables I use is required. Feedline looses per 100' @ given freq. are generally provided by the mfg. If you would like a copy of my work sheet (Tables included) email me direct. N3DAB/WPRX486 GMRS/WPJL709 LM --- In [email protected], [EMAIL PROTECTED] wrote: > > "n3dab" <[EMAIL PROTECTED]> wrote: > >You can go to the FCC site and pull Part 95 like I just did and read > >it for yourself. > > > >I'm running 50w from my Micor rptr. xmtr. with 1.5db loss from a MOt. > >1504 duplexer into 50' of 1/2' LDF4-50 heliax to a DB410 9.2db gain > >omni antenna. This all calculates out to approx. slightly more than > >250W ERP. This machine has been in service for at least 25 years on > >462/467. 675 in the Atlanta Ga. area > > > >N3DAB/WPRX486 GMRS/WPJL709 LM > Doug, > Can you show us your formula for converting power output to ERP? I guess, power out(watts) - (1.5db)+(50' of LDF$-50)+9.2db=ERP output. > > More details please. > Thanks. > 73's, > Jim Kh6jkg. > > > __________________________________________________________________ > Switch to Netscape Internet Service. > As low as $9.95 a month -- Sign up today at http://isp.netscape.com/register > > Netscape. Just the Net You Need. > > New! Netscape Toolbar for Internet Explorer > Search from anywhere on the Web and block those annoying pop-ups. > Download now at http://channels.netscape.com/ns/search/install.jsp > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
