RE: [drakelist] RIF: S meter to be or not to be

[David M Eakins]

Good morning all,   The “standard” in the US has always been what ever the manufacturer has specified in the manual for a particular rig. Most of the older equipment I have seen use 50 mv into 50 ohms as the s9 standard, some use more. What ever your book says it is, is the standard for that radio. If it is not specified, I would use the 50 mv setting and then put it on an antenna and see how it indicates apposed to how loud someone sounds on the speaker (a judgment call). Remember, the meter is a “relative signal strength” not an absolute. As to the rating per S unit, I have seen US manufactured equipment as well as Japanese that have used 3 DB per S unit but most, when specified used 6 DB. Since there is no “Standard” you will have to use your own judgment if not specified in your manual.   When asked for a critical signal report from someone I know to be a technician, I always specify how my S-meter is calibrated, unless I don’t know. Otherwise, I just tell them they loud, weak, or average, or give them a subjective number from 1-10 with 10 being the strongest signal I can measure with my receiver.   Now that is as much of a definite maybe as I can give.   73,   Mike - K7OV   -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Herbert Schulz Sent: Tuesday, March 23, 2004 1:12 AM To: mailbox55122 Cc: [EMAIL PROTECTED] Subject: Re: [drakelist] RIF: S meter to be or not to be   Months ago, i have read in a publication, that "S9" in the US corresponds to 50[�V] into 50[Ohms] and that one S-unit is 5[dB]. In Europe, "S9" is equal to 100[�V] into 50[Ohms] and one S-unit corresponds to 6[dB]. I have to double check, if my remembrance according this article is right, but i think so. Now, assume three cases (let's assume, that the S-meters are displaying a perfect log scale, which is almost never the case in reality; furthermore let's assume, that Drake's "S9 = 30[�V] into 50[Ohms]" statement is based on the "5[dB] per S-unit" definition): - S9 = 100[�V] into 50[Ohms] / 6[dB]:  S1 then equals to 0.39[�V] - S9 = 50[�V] into 50[Ohms] / 5[dB]:   S1 then equalt to 0.50[�V] - S9 = 30[�V] into 50[Ohms] / 5[dB]:   S1 then equals to 0.30[�V] The manual of my R-4C states a sensivity of better than 0.25[�V] at a noise ratio (S+N)/N = 10[dB] in the ham bands and better than 0.50[�V] at noise ratio (S+N)/N = 10[dB] on other frequencies. As S1 normally is a indication of the receivers sensivity at its noise limit, and this readout should be given at the receivers worst- case sensivity value (which is "0.50[�V] on other frequencies" accor- ding to the R-4C specification), i would suggest to use the US-defini- tion "S9 = 50[�V] into 50[Ohms] at a 5[dB] per S-unit scale" here. Regards and 73 from   Herbert, DG7MCC       mailbox55122 schrieb: Hi friends, on the R4C manual is stated that S9 on the S meter means 30 microvolts of RF signal at the antenna input. It looks that the standard S9 signal are 100 microvolts of RF signal (on 50 ohm)..... Where is the true? Or better, what is the real S9 value? 73 de IOKPL, Pietro     ---------------------------------------------------------------------- Submissions:        [EMAIL PROTECTED] Subscribe:          [EMAIL PROTECTED] - subscribe drakelist in body Unsubscribe:        [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:    [EMAIL PROTECTED] - help in body of message Brought to you courtesy of TLCHost.net  http://www.tlchost.net/ ----------------------------------------------------------------------