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THE AM BULLETIN BOARD => Technical Forum => Topic started by: N1ZR on February 09, 2005, 05:23:15 PM



Title: Using Cheapo Electrets on Boatanchors
Post by: N1ZR on February 09, 2005, 05:23:15 PM
I've got several electret mike elements rolling around the bottom of my parts box. I see via Google that there are schematics galore for simple preamplification of these for low impedance applications such as PC and on silly-state rigs. But what about for high-Z uses? Maybe a design that's small enough to fit into a hand mike (with requisite battery, of course)? tu


Title: Using Cheapo Electrets on Boatanchors
Post by: W2VW on February 09, 2005, 07:01:01 PM
Those little condensor mics already have plenty of output. You can drive a high impedance mic circuit with a low impedance mic. The reverse is where you will run into problems. The major drawback is that these mics usually have a bump in mid bass response and will need some shaping of the frequency response in order to not sound muddy.


Title: Using Cheapo Electrets on Boatanchors
Post by: W1GFH on February 09, 2005, 07:26:38 PM
One of the local guys here was recently experimenting with these little electret elements. He said if you can somehow mount them in free space (ring n' spring mount?) they have a pretty flat response that you can then tweak with outboard EQ. Or you can mount them in a tube with a hole at the end, varying the size of the hole will shape the response.


Title: electret mikes
Post by: ve6pg on February 12, 2005, 05:52:40 PM
ok...a friend of mine,ve3maw ken uses one on his old boatanchors..he just applies the 9 volts to the element,then to a impedance matching device into the transmitter. radio shack sells the impedance device,so it will take the element up to a high output for your rig. that is why i posted earlier about a impedance matching transformer..i want to do the same as you,but dont want to shell out the 20 bux for it at radio shack,then get another connector to match the xlr jack..inside most modern desk mikes is a matching transformer of some type. the kenwood mc60 has 2 levels,500ohms,and 50k..the 50k is what you want fer the boat anchor.
  anyway,ve3maw doesnt have anything weird with his mike,just the electret element,9volt battery and the lo to hi transformer..you can get one at the shack,and you are all set...no eq,tubes,etc...ken sounds great just as i described it...hope this helps...73..tim...ve6pg/3  qsx 3725kcs am...
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