Re: [AMRadio] Microphone assistance
. I was thinking of a transformer in the microphone case and the 9 foot cord which goes against my grain. I know we can make any of them work. When I hear AM radio guys talk about HighZ I think of a D-104 and it's ilk at about 5 megohms, this is high Z! When I hear 30K ohms I am thinking of a Hi-Z SSB like Kenwood TS520s,Drakes and Collins. That is what they call high Z. Most broadcast mics, I think are about 50 ohms ( dynamic types). I notice that a Shure 515SB is rated at 150 ohms, actual is 170 ohms and is for use on 19 to 300 ohm inputs..I too like the mixer plan.. 73.. Mike - Original Message - From: "John E. Coleman (ARS WA5BXO)" <[EMAIL PROTECTED]> To: "'Mike Dorworth, K4XM'" <[EMAIL PROTECTED]>; "'Discussion of AM Radio in the Amateur Service'" Sent: Thursday, August 31, 2006 5:40 PM Subject: RE: [AMRadio] Microphone assistance > You are correct Mike, > One way to help with the cable capacitance trouble, if a XFMR is to > be used to step up the voltage, is to put the XRMR close the input circuit > or preferably in the speech amp chassis and incorporate a 3 pin XLR > connector. Run balanced low Z from the microphone to the XLR input and > using the shield of the cable for just a shield and not common the audio of > the microphone. The mixer is a good plan if available and may have other > uses. __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Microphone assistance
There are transformers made into a mic plug. - Original Message - From: "david knepper" <[EMAIL PROTECTED]> To: ; <[EMAIL PROTECTED]> Sent: Thursday, August 31, 2006 3:29 PM Subject: [AMRadio] Microphone assistance Can anyone assist me in converting a low impedence microphone to high impendence. I bought several 600 ohm studio microphones (plastic housing) that come with a 9 foot cable and microphone plug. I am interested in using the microphone with a high impedence input transmitter on AM. Any suggestions? Perhaps, I should use a mixer unit that has low impedence input with a high impedence output. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Microphone assistance
The response was overwhelming. Thank you all. Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST - Original Message - From: "Jay Adrick" <[EMAIL PROTECTED]> To: Sent: Thursday, August 31, 2006 7:46 PM Subject: RE: [AMRadio] Microphone assistance - Message: 1 Date: Thu, 31 Aug 2006 16:29:10 -0400 From: "david knepper" <[EMAIL PROTECTED]> Subject: [AMRadio] Microphone assistance To: , <[EMAIL PROTECTED]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Can anyone assist me in converting a low impedence microphone to high impendence. I bought several 600 ohm studio microphones (plastic housing) that come with a 9 foot cable and microphone plug. I am interested in using the microphone with a high impedence input transmitter on AM. Any suggestions? Perhaps, I should use a mixer unit that has low impedence input with a high impedence output. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST Dave You need to properly match the low impedance broadcast microphone to you Hi Z rig input using a matching transformer. The solution that I have used here is a Heil Sound transformer that I picked up at the local ham store for $15. It has a 600 Ohm winding and a 30K Ohm winding, is small in size and is rated a microphone rather than line levels. My low Z sources work great into the S-Line using the transformer built up in a small diecast box with connectors. I have one version for microphone level input and another with a 60db pad in front of the transformer so that I can feed the rig with the broadcast audio chain Check Bob's web site and you will find the transformer listed under his microphone accessories. I run a Harris broadcast audio console and professional processing here and have also used the transformers to match HI Z microphones into the microphone inputs on the console. All the best Jay K8CJY __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Microphone assistance
- Message: 1 Date: Thu, 31 Aug 2006 16:29:10 -0400 From: "david knepper" <[EMAIL PROTECTED]> Subject: [AMRadio] Microphone assistance To: , <[EMAIL PROTECTED]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Can anyone assist me in converting a low impedence microphone to high impendence. I bought several 600 ohm studio microphones (plastic housing) that come with a 9 foot cable and microphone plug. I am interested in using the microphone with a high impedence input transmitter on AM. Any suggestions? Perhaps, I should use a mixer unit that has low impedence input with a high impedence output. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST Dave You need to properly match the low impedance broadcast microphone to you Hi Z rig input using a matching transformer. The solution that I have used here is a Heil Sound transformer that I picked up at the local ham store for $15. It has a 600 Ohm winding and a 30K Ohm winding, is small in size and is rated a microphone rather than line levels. My low Z sources work great into the S-Line using the transformer built up in a small diecast box with connectors. I have one version for microphone level input and another with a 60db pad in front of the transformer so that I can feed the rig with the broadcast audio chain Check Bob's web site and you will find the transformer listed under his microphone accessories. I run a Harris broadcast audio console and professional processing here and have also used the transformers to match HI Z microphones into the microphone inputs on the console. All the best Jay K8CJY __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Microphone assistance
Dave and all...Heil has a mini transformer that sometimes you can put in the mike I have a turner studio mike with a Heil built in works great...But as others have told You Guitar Center is a great source or Musicians Friend on line... I have an old Shure Transformer Brand new but would not sell for $10...Radio Shack has an XLR Input cable connector Bob W1PE -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of david knepper Sent: Thursday, August 31, 2006 3:29 PM To: amradio@mailman.qth.net; [EMAIL PROTECTED] Subject: [AMRadio] Microphone assistance Can anyone assist me in converting a low impedence microphone to high impendence. I bought several 600 ohm studio microphones (plastic housing) that come with a 9 foot cable and microphone plug. I am interested in using the microphone with a high impedence input transmitter on AM. Any suggestions? Perhaps, I should use a mixer unit that has low impedence input with a high impedence output. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Microphone assistance
I read that a low-Z mic has a low source Z, but it wants to see a high load Z. The trick with a preamp is to present a high Z to the mike, but produce minmum noise with a low-Z source. But that's for perfectionists. A transformer will work fine. Capacitive loading at the hi-Z side will affect highs, even a few feet of coax is enough to be noticeable. So the transformer should be fairly close to the radio. Since the transformer inductance and the RF filrtering and cable capacitance will be shunting the mic, some resistive loading (10K, more or less) on the high-Z side might help the frequency response, at the expense of level. About two feet of shielded cable would allow the audio transformer to be a little bit removed from the power transformers, and might help keep hum out of it. I think Radio Shack carries audio transformers of this type. Bacon, WA3WDR __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Microphone assistance
You are correct Mike, One way to help with the cable capacitance trouble, if a XFMR is to be used to step up the voltage, is to put the XRMR close the input circuit or preferably in the speech amp chassis and incorporate a 3 pin XLR connector. Run balanced low Z from the microphone to the XLR input and using the shield of the cable for just a shield and not common the audio of the microphone. The mixer is a good plan if available and may have other uses. Mine also has compression using a Light Dependent Resistance device to regulate the audio level. John WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Microphone assistance
The trouble with low z microphones is that some times Once a Hi-Z mike sends it's signal out it needs a short low capacity cable to keep from effectively shorting the highs. Putting a transformer in the mike is ok as long as the cord is low capacity and short. The 9 foot cord sounds like a disaster waiting to happen. The reason, I thought, for the LowZ mics was so a long cable, 20, 30 40 50 feet would not suffer such troubles. The idea of a mixer and then the Z conversion sounds good.. Just another $0.02.. Mike __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Microphone assistance
The trouble with low z microphones is that some times the output of the mic is too low and you don't have enough gain to get the modulation up high enough. If you do have enough gain then they work just fine in the hi-z input circuit. Beware that some input circuits do not have, or use, a coupling capacitor and the grid sets high above ground at 2.2 Meg or more, and develops contact bias. (no cathode bias resistor) The circuit works well with a ceramic or crystal microphone which has no continuity to ground but put a microphone which has continuity to ground such as a dynamic, even if it has a matching transformer, and it will kill the bias on the preamp causing the stage to operate in a distorted manner. If you don't want to go into the rig and modify the input circuit with a coupling cap then put one in the microphone to block the bias drain. The dynamic microphone will have a responds curve which extends much lower that the Xtal or ceramic so to balance it out you may want to do some extending of the high frequency range as well. You may also reduce the size of the coupling capacitor that you use at the input to limit the low frequency to a more expectable response for the rig. John WA5BXO __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Microphone assistance
The easiest way is to buy a transformer from some place like Guitar Center that does that very thing. You can usually find them in a variety of plug configurations nd they allow you to go from Hi Z to Lo Z or visa versa. Heil also sells a small transformer that will probably fit inside your mic that will do the same. Rick david knepper wrote: Can anyone assist me in converting a low impedence microphone to high impendence. I bought several 600 ohm studio microphones... __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Microphone assistance
On 8/31/06, david knepper <[EMAIL PROTECTED]> wrote: Can anyone assist me in converting a low impedence microphone to high impendence. I bought several 600 ohm studio microphones (plastic housing) that come with a 9 foot cable and microphone plug. I am interested in using the microphone with a high impedence input transmitter on AM. Any suggestions? Perhaps, I should use a mixer unit that has low impedence input with a high impedence output. Nah, just rip out the innards and stuff one of them thar Heil elements inside. Guaranteed to improve yer monkey swing... :D ~ Todd, KA1KAQ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Microphone assistance
You can use the mixer as stated or use a microphone transformer to go from low to high or make a simple 1 transistor amp with a NPN or PNP and it should work. Healthfully yours, Don W4BWS - Original Message - From: "david knepper" <[EMAIL PROTECTED]> To: ; <[EMAIL PROTECTED]> Sent: Thursday, August 31, 2006 3:29 PM Subject: [AMRadio] Microphone assistance > Can anyone assist me in converting a low impedence microphone to high > impendence. I bought several 600 ohm studio microphones (plastic housing) > that come with a 9 foot cable and microphone plug. I am interested in using > the microphone with a high impedence input transmitter on AM. Any > suggestions? > > Perhaps, I should use a mixer unit that has low impedence input with a high > impedence output. > > Thank you > > Dave, W3ST > Publisher of the Collins Journal > Secretary to the Collins Radio Association > www.collinsra.com - the CRA Website > Now with PayPal > CRA Nets: 3805 Khz every Monday at 8 PM EST > and 14255 every Saturday at 12 Noon EST > > __ > AMRadio mailing list > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Partner Website: http://www.amfone.net > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:AMRadio@mailman.qth.net > __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Microphone assistance
Can anyone assist me in converting a low impedence microphone to high impendence. I bought several 600 ohm studio microphones (plastic housing) that come with a 9 foot cable and microphone plug. I am interested in using the microphone with a high impedence input transmitter on AM. Any suggestions? Perhaps, I should use a mixer unit that has low impedence input with a high impedence output. Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3805 Khz every Monday at 8 PM EST and 14255 every Saturday at 12 Noon EST __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
