Search results

Like I keep telling you, the benefits of the narrow RBW apply to small continuous wave signals, eg a steady carrier that can sit inside the 10Hz RBW. Noise isn't a continuous wave signal. So reducing the RBW offers no benefit when measuring noise power. Consider this set of conditions...

Note that this would be a much better place to tap into the radio than TP13 because there will be sufficient gain to overcome the poor noise figure of the spectrum analyser without needing a preamp. However, I would be (slightly) concerned about loading the IF circuit and also it may cause...

What about this question- Your cobra has the same sensitivity as the TRC then (.25 uV for SSB and 0.5 uV for AM). Working to 50 Ohms, 0.7uV is equivalent to -110dBm, which is close to receive threshold for S/N of 10dB. What is the displayed noise floor of your radio at I/F with your...

You are right, we aren't in agreement on the use of the resolution BW to measure low level signals. This is an excerpt from my 1971 HP text "Electronic Measurements and Instrumentation", chapter 16-8 : "Sensitivity The ability of the swept superheterodyne spectrum analyzer to measure...

Have you looked at the noise floor of these types of receivers? Its in the -125dBm range, and goes much higher, when you crank up the RF gain. Turn the radio off, floor goes to about the -130dBm range for mine at, depending on RES BW and how much time I want to spend on the scan at that setting...

Yes, if you select 10Hz BW this is true for discrete and narrow signals that are less than 10Hz wide but you are in the business of measuring noise levels so going down to 10Hz RBW doesn't make the analyser more capable in terms of measuring low noise levels. Wrong on that. Think of the 10...

Agree with your last, I use this nomograph to get a quick visual of noise floor at various NFs and BWs. I extended the right side BW line down at the same decade spacing to 10 Hz. Even a 24 dB NF will be very sensitive, with a narrow enough BW...

PLease read through- http://www.teknetelectronics.com/DataSheet/HP_AGILENT/HP_8443a.pdf with a 10 Hz resolution BW ( slow scan in storage mode), it has enough sensitivity to measure signals above a -140 dBm noise floor. That's way below the quiesent floor of the radio. I'll post the...

See post #145 of this thread. It measures. I also use this rig (has both a 50 ohm and a 600 ohm input impedance) to align FM tuner RF/ IF sections, constantly. Our mainstay analyzer (Hughes Space and Communications) in the 80s was the HP 8566 (2-22 gHz model). It was 60K then. This radio...

Using the stated sensitivity of the radio of .5uV for 10 dB S/N- Equates to ~ -112dBm carrier power at the input to the radio. With a 1 dB gain antennna with 1 dB cabling loss to radio, the dBW/M2 at the antenna aperture is -152 dBW at 27 MHz, with a working BW of 3 KHz. System Noise...

Wouldn't try to measure audio S/N with an RMS AC voltmeter. The LF 8556 section of the HP will do that though, with a 1 KHz test signal modulated on the carrier from the signal generator. That's a good test to add, along with the carrier to noise ratio tests. The diode switching noise in AM...

Check out this document: http://cp.literature.agilent.com/litweb/pdf/5952-1147.pdf You are confusing recevier NF with antenna noise temperature, which includes the effects of the sky temperature when determining an estimate for the total noise power in the receiver's frequency and BW. As...

No. The 433 is about 15 years newer than the fabled UPD858 based uniden. It is a remarlably good little base, that is as sensitive as the 458 on AM. I haven't done the 2SC2999e mod to the 458 yet, for one reason. Addiction to SSB (namely ch 38 LSB). On SSB, the 458 lets me hear the 11 meter...

Finally built a good dummy 50 ohm load with shielded test leads for my scope. Verified the yet unopened TRC 433 (good receiver side) put out a constant 3.99 watts, with 40 volts peak to peak accross the load (no modulation), and very nice modulation waveform (used a wavetek 180 audio oscillator...

Watergate, I think you nailed it. I work in Prince William County, and "Ireland" now makes sense. I was just scanning this am for people preparing for a possible snow storm today, and heard these blokes !

OK.... Also looked for local repeaters on line at 147.405 and didn't find any... Really strange. Tried to reply and introduce myself but they were impervious to that.

Just listened to three folks on a repeater in England (147.405 Mhz) talk on their mobile, for about 20 minutes. They were on a repeater, and the accent of the repeater clinched it. From northern Va, 7:00 am local. Rig is ICOM 2100H mobile.

How do you like that TRC 458? Its my first SSB rig, stock (which was good), and I have been through mine many times using the SAMS manual to align the receive and transmit side. I have all the test equipment, since my main hobby is aligning FM tuners for audiophile work. I live on a small ridge...

With the EZNEC antenna designed 1/2 wave vertical dipole, I can clearly hear England and Ireland in the morning, and the west coast of the US in the evening, with Texas and Ontario midday, from Eastern Virginia. Haven't made a contact yet, but the TRC 458 is almost clearer in SSB mode than...

I'm running a TRC 458 with 1/2 wave vertical dipole in a tree (designed with EZNEC SW) and hearing a lot of traffic around the US and Mexico. I just got into this CB hobby, and found this radio just in time (for the sun spot cycle). Great to hear that I can use this radio as is to try and...