Difference between revisions of "Talk:Microphone Impedance for Amateur Radio"
(Created page with "==Turner 254 Replacment Element== You could probably successfully use one of the modern cheap electret elements to drive your FT-101. The problem is you need DC to run the mic...") |
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==Turner 254 Replacment Element== | ==Turner 254 Replacment Element== | ||
You could probably successfully use one of the modern cheap electret elements to drive your FT-101. The problem is you need DC to run the mic. Presumably not easily available at the mic plug, it would require modifying the radio to put DC from the radio onto the audio line and then block the DC inside the radio with a cap. Or put a battery in the base of the microphone. That could work if you have a switch contact available to just let DC current flow to the mic when the PTT is pressed down to save battery. The FT 101 works quite excellent with a Shure 444 microphone, or the possibly cheaper to acquire 450 with the switch in the hi Z position on the bottom. That is, the Shure mic is hi Z like 50,000 ohms but not the megohms hi Z of a crystal or ceramic mic. I am pretty sure that the original Yaesu mics were low impedance mics with a stepup transformer inside them. A purely hi Z crystal mic would probably be a better match to the HT 40 tube rig than the solid state Yaesu. | You could probably successfully use one of the modern cheap electret elements to drive your FT-101. The problem is you need DC to run the mic. Presumably not easily available at the mic plug, it would require modifying the radio to put DC from the radio onto the audio line and then block the DC inside the radio with a cap. Or put a battery in the base of the microphone. That could work if you have a switch contact available to just let DC current flow to the mic when the PTT is pressed down to save battery. The FT 101 works quite excellent with a Shure 444 microphone, or the possibly cheaper to acquire 450 with the switch in the hi Z position on the bottom. That is, the Shure mic is hi Z like 50,000 ohms but not the megohms hi Z of a crystal or ceramic mic. I am pretty sure that the original Yaesu mics were low impedance mics with a stepup transformer inside them. A purely hi Z crystal mic would probably be a better match to the HT 40 tube rig than the solid state Yaesu. | ||
| + | == Other microphones and CB microphones == | ||
| + | |||
| + | CB Power Microphones are generally poor choices for modern amateur radio transceivers. Too much audio gain, users have to almost turn off these pre-amps for clean audio. The native Shure dynamic mic element, R96, usually has very good audio. IF the microphone's internal components (mic element, pre-amp board) have been modified/changed or replaced --- restoration work would be required for usage with your Yaesu FT-950. | ||
| + | |||
| + | The original 526-T was marketed in 1970s for the CB Power Microphone buyers. The 526-T Series II incorporated component changes in 1980s and marketed as a transistorized desk microphone. The 526-T Series II User Guide discusses improper usage (too much pre-amp gain). This is one reason the microphone was finally discontinued. | ||
| + | |||
| + | When the 526T Series II replaces a dynamic (usually low– impedance) microphone supplied as original equipment, the volume control should be set at the lower ranges to prevent overmodulation and unintelligible transmission. Correct modulation can be checked on the modulation level indicator. | ||
| + | |||
| + | When the 526T Series II replaces a ceramic (usually high- impedance) microphone supplied as original equipment, the volume control should be set at the upper ranges for correct modulation as indicated on the modulation level indicator. | ||
| + | |||
| + | WARNING | ||
| + | Too high a volume control setting causes over- modulation, interference, channel splatter, and unintelligible voice transmission. Carefully check the volume control setting. | ||
| + | |||
| + | == CB power microphones == | ||
| + | |||
| + | The majority of CB power microphones don't sound very good on amateur radio equipment. I have nothing against them in terms of their CB heritage or anything like that, it's just they are simply not very good in terms of producing any acceptable level of quality audio reproduction. | ||
| + | |||
| + | If you ever heard one on the air, you will note the many problems associated with using them such as the audio reflecting off the walls in the shack creating an echo like artifact distortion in the signal. This makes it especially difficult for others to understand what they are saying even when they are using phonetics to spell things out. | ||
| + | |||
| + | Another problem with these microphones is they are often poorly designed in terms of any directional pattern characteristics too. They tend to pick up a lot of fan and other equipment noise in the shack. | ||
| + | |||
| + | Those characteristics in a microphone are just not the mark of a good sounding microphone in my opinion... sorry, but it just isn't. :) | ||
| + | |||
| + | A better choice would be to pick up a cheap, and somewhat more professional grade audio recording style microphone for your rig. These are not expensive. Ebay and others have these kind of microphones for as little as 20 bucks. These are way better microphone choices for your modern amateur radio equipment. The old CB stuff, not so much. | ||
Latest revision as of 15:22, 8 November 2017
Turner 254 Replacment Element
You could probably successfully use one of the modern cheap electret elements to drive your FT-101. The problem is you need DC to run the mic. Presumably not easily available at the mic plug, it would require modifying the radio to put DC from the radio onto the audio line and then block the DC inside the radio with a cap. Or put a battery in the base of the microphone. That could work if you have a switch contact available to just let DC current flow to the mic when the PTT is pressed down to save battery. The FT 101 works quite excellent with a Shure 444 microphone, or the possibly cheaper to acquire 450 with the switch in the hi Z position on the bottom. That is, the Shure mic is hi Z like 50,000 ohms but not the megohms hi Z of a crystal or ceramic mic. I am pretty sure that the original Yaesu mics were low impedance mics with a stepup transformer inside them. A purely hi Z crystal mic would probably be a better match to the HT 40 tube rig than the solid state Yaesu.
Other microphones and CB microphones
CB Power Microphones are generally poor choices for modern amateur radio transceivers. Too much audio gain, users have to almost turn off these pre-amps for clean audio. The native Shure dynamic mic element, R96, usually has very good audio. IF the microphone's internal components (mic element, pre-amp board) have been modified/changed or replaced --- restoration work would be required for usage with your Yaesu FT-950.
The original 526-T was marketed in 1970s for the CB Power Microphone buyers. The 526-T Series II incorporated component changes in 1980s and marketed as a transistorized desk microphone. The 526-T Series II User Guide discusses improper usage (too much pre-amp gain). This is one reason the microphone was finally discontinued.
When the 526T Series II replaces a dynamic (usually low– impedance) microphone supplied as original equipment, the volume control should be set at the lower ranges to prevent overmodulation and unintelligible transmission. Correct modulation can be checked on the modulation level indicator.
When the 526T Series II replaces a ceramic (usually high- impedance) microphone supplied as original equipment, the volume control should be set at the upper ranges for correct modulation as indicated on the modulation level indicator.
WARNING Too high a volume control setting causes over- modulation, interference, channel splatter, and unintelligible voice transmission. Carefully check the volume control setting.
CB power microphones
The majority of CB power microphones don't sound very good on amateur radio equipment. I have nothing against them in terms of their CB heritage or anything like that, it's just they are simply not very good in terms of producing any acceptable level of quality audio reproduction.
If you ever heard one on the air, you will note the many problems associated with using them such as the audio reflecting off the walls in the shack creating an echo like artifact distortion in the signal. This makes it especially difficult for others to understand what they are saying even when they are using phonetics to spell things out.
Another problem with these microphones is they are often poorly designed in terms of any directional pattern characteristics too. They tend to pick up a lot of fan and other equipment noise in the shack.
Those characteristics in a microphone are just not the mark of a good sounding microphone in my opinion... sorry, but it just isn't. :)
A better choice would be to pick up a cheap, and somewhat more professional grade audio recording style microphone for your rig. These are not expensive. Ebay and others have these kind of microphones for as little as 20 bucks. These are way better microphone choices for your modern amateur radio equipment. The old CB stuff, not so much.
