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I haven't gone over the math but have big questions about the numbers being quoted. Where are you getting your gain and loss figures?

0.5dB per connector is excessive (even for a PL259). Changing to just 0.1dB per connector is likely high at 27MHz. 1dB for each of the switch box, LPF, and wattmeter are way too high. Just those three alone would eliminate half your transmitter power! Without accurate figures everything you say and any conclusions being made are meaningless.

Power gain = 10 log (P1/P2)

Every 3dB is essentially a doubling of power. -3dB is half power. If your system had 9dB loss, the output power would be 1/8 or 12.5% of what went in!

In practice, even 3dB is often not noticeable to a distant receiver. You could double (or half) your transmit power with little or no difference. Try it out for yourself if you have an accurate way to change transmit power by 3dB or if you have a good 3dB attenuator to install on your antenna receive line.

The only figures you've quoted that look reasonable are for the feedline loss. I haven't confirmed the numbers and will assume them to be accurate. The loss difference between your two feedlines is 0.56dB. Anyone who can measure that difference after the signal leaves the antenna has too much money tied up in test equipment. I've used $50k spectrum analyzers that will not resolve to that level on a receive signal. Unless the cable is damaged, I'd suggest putting your money elsewhere.

ERP is a calculated value based on overall system gain / loss. It can not be measured. You don't have 25 watts ERP into an antenna. You could calculate 25 watts arriving at an antenna after losses are calculated, or you could calculate 25 watts ERP after factoring in antenna gain with system losses and transmitter output power.

You mentioned 50 watts with 5.64dB loss. Let's assume it's 6dB instead. You will never notice the 0.36dB difference. The output power would be about 1/4 or 12.5 watts.

A more exact calculation would be 50 / 10^0.564 = 13.64 watts

Here's a good site to read on decibels.
http://www.dxing.com/tnotes/tnote10.pdf

Wikipedia is your friend too.

<blockquote data-quote="vo1ks" data-source="post: 352156" data-attributes="member: 24212">I haven&#039;t gone over the math but have big questions about the numbers being quoted.&nbsp; Where are you getting your gain and loss figures?0.5dB per connector is excessive (even for a PL259).&nbsp; Changing to just 0.1dB per connector is likely high at 27MHz.&nbsp; 1dB for each of the switch box, LPF, and wattmeter are way too high.&nbsp; Just those three alone would eliminate half your transmitter power!&nbsp; Without accurate figures everything you say and any conclusions being made are meaningless.Power gain = 10 log (P1/P2)Every 3dB is essentially a doubling of power.&nbsp; -3dB is half power.&nbsp; If your system had 9dB loss, the output power would be 1/8 or 12.5% of what went in!In practice, even 3dB is often not noticeable to a distant receiver.&nbsp; You could double (or half) your transmit power with little or no difference.&nbsp; Try it out for yourself if you have an accurate way to change transmit power by 3dB or if you have a good 3dB attenuator to install on your antenna receive line.The only figures you&#039;ve quoted that look reasonable are for the feedline loss.&nbsp; I haven&#039;t confirmed the numbers and will assume them to be accurate.&nbsp; The loss difference between your two feedlines is 0.56dB.&nbsp; Anyone who can measure that difference after the signal leaves the antenna has too much money tied up in test equipment.&nbsp; I&#039;ve used $50k spectrum analyzers that will not resolve to that level on a receive signal.&nbsp; Unless the cable is damaged, I&#039;d suggest putting your money elsewhere.ERP is a calculated value based on overall system gain / loss.&nbsp; It can not be measured.&nbsp; You don&#039;t have 25 watts ERP into an antenna.&nbsp; You could calculate 25 watts arriving at an antenna after losses are calculated, or you could calculate 25 watts ERP after factoring in antenna gain with system losses and transmitter output power.You mentioned 50 watts with 5.64dB loss.&nbsp; Let&#039;s assume it&#039;s 6dB instead.&nbsp; You will never notice the 0.36dB difference.&nbsp; The output power would be about 1/4 or 12.5 watts.A more exact calculation would be 50 / 10^0.564 = 13.64 wattsHere&#039;s a good site to read on decibels.<a href="http://www.dxing.com/tnotes/tnote10.pdf" target="_blank">http://www.dxing.com/tnotes/tnote10.pdf</a>Wikipedia is your friend too.</blockquote>

[QUOTE="vo1ks, post: 352156, member: 24212"] I haven't gone over the math but have big questions about the numbers being quoted. Where are you getting your gain and loss figures? 0.5dB per connector is excessive (even for a PL259). Changing to just 0.1dB per connector is likely high at 27MHz. 1dB for each of the switch box, LPF, and wattmeter are way too high. Just those three alone would eliminate half your transmitter power! Without accurate figures everything you say and any conclusions being made are meaningless. Power gain = 10 log (P1/P2) Every 3dB is essentially a doubling of power. -3dB is half power. If your system had 9dB loss, the output power would be 1/8 or 12.5% of what went in! In practice, even 3dB is often not noticeable to a distant receiver. You could double (or half) your transmit power with little or no difference. Try it out for yourself if you have an accurate way to change transmit power by 3dB or if you have a good 3dB attenuator to install on your antenna receive line. The only figures you've quoted that look reasonable are for the feedline loss. I haven't confirmed the numbers and will assume them to be accurate. The loss difference between your two feedlines is 0.56dB. Anyone who can measure that difference after the signal leaves the antenna has too much money tied up in test equipment. I've used $50k spectrum analyzers that will not resolve to that level on a receive signal. Unless the cable is damaged, I'd suggest putting your money elsewhere. ERP is a calculated value based on overall system gain / loss. It can not be measured. You don't have 25 watts ERP into an antenna. You could calculate 25 watts arriving at an antenna after losses are calculated, or you could calculate 25 watts ERP after factoring in antenna gain with system losses and transmitter output power. You mentioned 50 watts with 5.64dB loss. Let's assume it's 6dB instead. You will never notice the 0.36dB difference. The output power would be about 1/4 or 12.5 watts. A more exact calculation would be 50 / 10^0.564 = 13.64 watts Here's a good site to read on decibels. [url]http://www.dxing.com/tnotes/tnote10.pdf[/url] Wikipedia is your friend too. [/QUOTE]

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