Radio issues: carrier only, no voice

[SoloEqs]

Had a GE MASTR II

That was your first mistake.

Ma Batwings is the One True Transceiver.

 

[Hiperbiper]

Maybe one of the mike plugs is touching ground?
I looked at a 210 that had a similar problem and it was a loose mike jack that had eaten away the insulator rings. Hanging all the mike jacks in open air and the radio worked fine.

Just a thought.

Chris

 

[weirdjim]

Uh . . .no.

The IF is the intermediate frequency. You're talking about the IF oscillator, which PRODUCES the IF.

Modulation is present on the IF, and an IF can be heard outside the radio if you're close enough (or have a good antenna). Cops spot illegal radar detectors in commercial vehicles by transmitting a modulated signal in the appropriate bands, then "sniffing" for that modulation on the IFs found in common radar detectors. The next time you pass a DOT truck scale, look for an itty-bitty Yagi antenna aimed down to hit the cab of the truck.

However, that said, you're right that I was thinking about the signal before the PA.

Best way to get out of a hole is to stop digging. What you have just said is a totally incorrect series of statements. Stop now while you have a crumb of credibility left.

Jim

 

[SoloEqs]

Best way to get out of a hole is to stop digging. What you have just said is a totally incorrect series of statements. Stop now while you have a crumb of credibility left.

Jim

Funny thing, everything I said is actually true.

Here's one example, from the first page on a Yahoo search:

"The 400Hz low-frequency modulates the 465KHZ intermediate frequency signal through C3, and the MODULATED 465kHz INTERMEDIATE FREQUENCY SIGNAL is output by the emitter VT4. " [emphasis mine]

http://www.seekic.com/circuit_diagr...diate_frequency_signal_generator_circuit.html

So, that covers modulation on an IF.

And, on a radar signal:

"A microwave radar signal is generated (12) for transmission through an antenna (20). Before transmission, the signal is phase modulated (18) by 0.degree. or 90.degree. amounts during each alternate half-cycles of an intermediate frequency (IF) clock signal (26). After transmission and return, the signal is again phase modulated (18) the same amounts during each alternate half-cycles. The return phase modulated signal is mixed (24) with a leakage signal component of the microwave signal, leaving an IF doppler. The IF doppler signal may then be amplified (30), removing any requirement that direct current level signals be amplified and also removing the effect of detector noise from the doppler signal."

http://www.docstoc.com/docs/4577188...And-Reflected-Return-Signals---Patent-4439766

Now go look up "radar detector detector":

"A radar detector detector is designed to search for intermediate frequecy (IF) emitted from most car radar detectors. This IF produces radio frequency energy, and it can be detected. The IF used to be about 11GHz on all car radar detectors, but when the first radar detector detector came out, most radar detector companies moved their intermediate frequency to 15GHz. Then the radar detector detector companies started scanning at 11GHz and 15GHz. The radar detector detectors used today are the VG2, VG4, Spectre I, Spectre II, Spectre III and Stalcar (in Australia only). Each of these devices can detect one or both IF frequencies: VG2: 11GHz VG4: 11 and 15GHz Spectre I: 11GHz Spectre II: 11 and 15GHz Spectre III: 11 and 15GHz Stalcar: 11 and 15GHz"

Some new radar detectors automatically shut down when they get the signal from an RDD. They determine that a microwave signal is an RDD and not a Doppler radar based on the modulation of the signal. So, of course, the newest generation of RDD has counter-countermeasures . . .

So, that gives us 1) modulation on IF, 2) modulated IF used in Doppler radar, and 3) radar detector detection through reading the IF of the detectors.

 

[weirdjim]

Funny thing, everything I said is actually true.

Here's one example, from the first page on a Yahoo search:

"The 400Hz low-frequency modulates the 465KHZ intermediate frequency signal through C3, and the MODULATED 465kHz INTERMEDIATE FREQUENCY SIGNAL is output by the emitter VT4. " [emphasis mine]

http://www.seekic.com/circuit_diagr...diate_frequency_signal_generator_circuit.html

So, that covers modulation on an IF.

That's to make a signal generator to ALIGN an IF stage in a radio, not the radio itself. Get with the program

And, on a radar signal:

"A microwave radar signal is generated (12) for transmission through an antenna (20). Before transmission, the signal is phase modulated (18) by 0.degree. or 90.degree. amounts during each alternate half-cycles of an intermediate frequency (IF) clock signal (26). After transmission and return, the signal is again phase modulated (18) the same amounts during each alternate half-cycles. The return phase modulated signal is mixed (24) with a leakage signal component of the microwave signal, leaving an IF doppler. The IF doppler signal may then be amplified (30), removing any requirement that direct current level signals be amplified and also removing the effect of detector noise from the doppler signal."

http://www.docstoc.com/docs/4577188...And-Reflected-Return-Signals---Patent-4439766

That's for a monopulse doppler weather radar, a very specific and obscure way of generating a radar signal, not a plain-jane aircraft superheterodyne aircraft transceiver.

Not only is it obscure, it is unique and different enough to generate a patent. Hardly your common radio.

Now go look up "radar detector detector":

"A radar detector detector is designed to search for intermediate frequecy (IF) emitted from most car radar detectors. This IF produces radio frequency energy, and it can be detected. The IF used to be about 11GHz on all car radar detectors, but when the first radar detector detector came out, most radar detector companies moved their intermediate frequency to 15GHz. Then the radar detector detector companies started scanning at 11GHz and 15GHz. The radar detector detectors used today are the VG2, VG4, Spectre I, Spectre II, Spectre III and Stalcar (in Australia only). Each of these devices can detect one or both IF frequencies: VG2: 11GHz VG4: 11 and 15GHz Spectre I: 11GHz Spectre II: 11 and 15GHz Spectre III: 11 and 15GHz Stalcar: 11 and 15GHz"

Some new radar detectors automatically shut down when they get the signal from an RDD. They determine that a microwave signal is an RDD and not a Doppler radar based on the modulation of the signal. So, of course, the newest generation of RDD has counter-countermeasures . . .

So, that gives us 1) modulation on IF, 2) modulated IF used in Doppler radar, and 3) radar detector detection through reading the IF of the detectors.

No, sonny boy, YOU go look it up.

Radar detectors are built around a superheterodyne receiver, which has a local oscillator that radiates slightly. It is therefore possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz for the intermediate frequency). Some radar guns are equipped with such a device.

​

You aren't looking for the IF signal itself, you are looking for the leakage signal from the local oscillator that produces a beat between the received signal and the LO, which PRODUCES the intermediate frequency -- noted here as about 10 MHz. (actually 10.7 MHz) above OR below the radar gun's frequency. When the cops got wise to the leakage detection scheme, the detector folks used a whole bunch of tricks like double-balanced mixers that radiate zero of the LO, moving the IF from +/- 10.7 to 21.4 or 45 MHz, and a few other tricks.

I'm out of this senseless ping pong game. As somebody once noted, I refuse to have a battle of wits with an unarmed man.

Jim

 

[SoloEqs]

I'm out of this senseless ping pong game. As somebody once noted, I refuse to have a battle of wits with an unarmed man.

But, obviously, I'm willing to do so.

Have a nice day.

 

[Jeff K]

I'm out of this senseless ping pong game. As somebody once noted, I refuse to have a battle of wits with an unarmed man.

Jim

Worse then that, one who is getting his information off yahoo searches.

Presuming some radio background with your adversary, it sounds like it's with FM mobile band or ham 2 meter FM rigs where they are modulated at the beginning of the TX chain. AM transmitters almost always are modulated at the final PA. Hence, if the final blows out, you'll not have any modulation (carrier only) or low modulation if the driver is modulated also. Also your range is going to be measured in 100's of feet likely at that point.

 

[weirdjim]

Presuming some radio background with your adversary, it sounds like it's with FM mobile band or ham 2 meter FM rigs where they are modulated at the beginning of the TX chain. AM transmitters almost always are modulated at the final PA. Hence, if the final blows out, you'll not have any modulation (carrier only) or low modulation if the driver is modulated also. Also your range is going to be measured in 100's of feet likely at that point.

Precisely, and it is good to see that somebody else has done transistorized finals where the upsie isn't quite as easy to get as the downsie, so we up-modulate the driver as well to get over that 80% rule.

 

[Jeff K]

Honestly most of my AM transmitter work had been with CB radios back in college in the early 80's (10-4 with that) and then a time in TV broadcasting back in the analog days. The rest was FM, commercial radio and two-way. Still hold my first class/general radio telephone with radar endorsement/extra class ham ticket though.

These days I mostly do low power wireless design + firmware... mostly in the ISM bands. I have done some work on avionics in years past (mostly comms) but mostly makes me dangerous, not a seasoned veteran like yourself (as you know I've followed your col.s for some years... even had some of your gear in my last plane... and pleased to run into you here).

What got my attention was the protagonist's use of buzz words as well as slaughtering a few basic things (he was confusing the local oscillator with the IF in regards to what potentially radiates in one example).