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707
| | Posted on Tuesday, July 03, 2001 - 7:36 pm: | 
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If you are considering either having your radio modulation "tweaked" or you are buying a "tweaked and tuned" radio, seriously consider investing in a microphone with compression circuitry, rather than a straight "power mic". The audio compression will keep your peaks down, while increasing the average modulation. This will make you MUCH louder than just the straight power mic, and you'll have less splatter.
The truth is, most of the time, a stock radio with compression type mic will sound 100% better on the air than a "tweaked" radio.
Astatic makes some good hand mics with compression, and the all time great desk mic is the Turner Expander 500.
I lamented the demise of the original K40 Speech Processor mic. What a loss. Does anyone know where I could find one of these in good shape or new? |
HAM CBer
| | Posted on Wednesday, July 04, 2001 - 4:59 pm: |
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It seems the simpler of the two CB radios is still available: http://www.k40.com/k40cb/cb_radio.htm
The one that was comparable to the Cobra 29 apparently is no longer made.
The mic offered on that page does not seem to be the Processor mic. It would be a lot more expensive if it was. |
HAM CBer
| | Posted on Wednesday, July 04, 2001 - 4:44 pm: |
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I agree: A horrible shame about the K40 mic. I still have one of the brochures for this mic! They called their proprietary I.C. 'Charlie'. It had pictures of a scope with regular mic, regular power mic, and K40 mic. audio waveforms on it.
When K40 came out with their own line of AM only CB radios, they included the 'Charlie' chip in the radios and did away with the mics. Since the radios were a flop, why did they never bring back the mics????
They had a huge magnet on the back of them for hanging on anything metal (nothing but metal dashboads back then) and did it not even require a battery. There was a large capacitor that would charge up while you were receiving and that would power the I.C. while transmitting. You could talk for about 3 minutes before the capacitor drained and your audio cut off. It was easy to put a larger capacitor in the mic (plenty of space) for those who were longer winded than that. Also, there was a switch on the side for low frequency or high frequency response. The low worked great for AM, then switch to high for SSB and the result was awesome! SUPER clear SSB and a noticeable improvement in average power out for better range. I used the K40 mic. on a box stock radio and talked anywhere the linear lungs in town did.
As I remember, even the cord was above average quality, having used real rubber for the outer cover.
I miss the K40 mic. PLEASE get back to 707 if you have one and get back to me if you have two of them. I'd be willing to dump a month's allowance for one that worked. |
Santa
| | Posted on Sunday, July 08, 2001 - 5:51 am: |
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707 Which astatic mics. are compression mics.? The noise canceling ones or others? Do you know the model #.? |
707
| | Posted on Sunday, July 08, 2001 - 11:02 pm: |
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do not confuse noise cancelling with compression..it's totally different. Most generally, hand mics will not be compression mics, per se. The K40 was an exception.
One form of Speech Compression works by raising the average level of your modulation,using a fast automatic gain control, so that quieter syllables get ramped up, while louder ones get ramped down, while not letting the peak modulation go above a preset level. Another form, better referred to as limiting, simply ramps all the audio up to a preset level(drive), and just chops off anything over another preset level(clipping) Speech compression with no filtered voice frequency discrimination(like the K40 had) would be a nightmare in a noisy environment.
Noise cancelling works by a method of gating the audio so that in the absence of audio at a preset level, it essentially shuts the mic off. This occurs very quickly, so you don't really hear it happening, but you don't hear background noise, because it's not loud enough to open the gate between the voice audio peaks.
K40, with the "charlie" chip, managed to provide both compression and noise cancelling through use of a patented processing algorithm.
Most of the hand mic specs will specify if they have either gain, compression, or are noise cancelling. |
HAM CBer
| | Posted on Tuesday, November 06, 2001 - 3:37 pm: |
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I just received a K40 Speech Processor microphone I bought on ebay that had never been used. Since the mic has been sitting around in it's original box still, the microphone's cord dried out and cracks when moved around. I sent an email to K40 asking if I could purchase a new cord. The kind folks at K40 told me to just send them the whole mic along with $10 for return shipping and they will completely re-firb. it and send it back! WOW!!!!! So now, I am obviously sending this mic off to K40 for the refirb and new cord.
When it comes back, I can't wait to play with it some more. Man, those K40 people are unreal. |
Hamcber
| | Posted on Thursday, November 15, 2001 - 9:06 pm: |
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You know how some things sound too good to be true????
My K40 Speech Processor microphone's cord was old and cracking. Other than that, this microphone had never even been out of the box. K40 told me to send my Speech Processor mic to them with 10 dollars and they would re-firb it.
Well, I got my K40 mic back today still sealed in the box I sent it in, still with a cracked mic cord, untouched. Oh, there was a note: "Speech processor cords no longer available, return microphone to customer". And, just above that: "Warranty repair charge $10.00" THEY EVEN KEPT MY MONEY!!!!
So, not only did they LIE to me telling me they would refirb it, but they did nothing and kept my money anyway. ARGH! I guess I'll just drill out the strain releif and find a small cord that fits like my original plan was. Now, I wish I had just done that in the first place...
If they had just told me that in the first place, I still would have been O.K. with it. Now, after lying to me AND taking my money (so it was only 10 bucks, that's not the point), I will NEVER buy K40 again. Hope they're happy. No tears over K40 losing market share or the inevitable demise of K40, not from me. You are the weakest link, Good bye. |
Harpoonman
| | Posted on Friday, November 16, 2001 - 12:36 pm: |
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Ham,
I don't know whether you did this or not, but you need to contact K40, in writing, and explain the whole thing to them!! Perhaps telling them about it won't change anything or get your $10 back, but there will CERTAINLY be no changes if people don't stand up and "cry foul" at the appropriate times. And I think $10 is an IMPORTANT point! That could've been used for your repair supplies!
I'm always telling my wife that if you don't let a merhcant know when you are unhappy or unsatisfied, then they'll have no reason to make changes. For all we know, maybe there are 50 other customers out there who have been similarly robbed. If they all wrote stringent complaints (and if necessary complaints to the Better Business Bureau, etc.), K40 might begin to listen. You might even get that $10 back!
SQUEAL when your grease dries up!!!!
Harpoonman |
Hamcber
| | Posted on Saturday, November 17, 2001 - 12:24 am: |
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Good point.
I spoke with people at K40 on the phone (2 of them) and even explained the whole thing to them. One lady I spoke with was answering my questions about the mic as if she knew her stuff, so I know I had her attention. The same lady generated and gave me an R.A. number to use (which I did). When I sent the mic in, I even sent it to her attention.
My protest will be to avoid K40. That is punishment enough. |
HAM CBer
| | Posted on Saturday, November 17, 2001 - 7:38 pm: |
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Well, good news! I just got finished re-working the cord for my 'new' K40 Speech Processor mic. My repairs changing the old for the new cord are undetectible as anything but box-stock. I got to hook it up to my main rig today... Man, does this thing talk!!
It's not that it added any modulation, it's mainly what you see when viewing the received audio waveform on the scope that describes it best. With my stock mic, I see the audio waveform as a straight line that moves around when I speak. On high level audio, the line dips down to the line referenced as 100% negative peak while the tops of the peaks reach near the line representing 150% positive peaks. With the K40 Speech Processor mic., the audio levels are the same, but there is a LOT more line movement and 'stuff' all over the scope.
It's odd, but when whistling, there is no difference between the K40 and the stock mic. When speaking, there is a LOT of difference.
What it sounds like on the air is clean and no different from a really high quality mic, except that it sounds like someone turned your volume up just for me when I talk.
THAT ought to confuse the locals some more.... |
Bikerider
| | Posted on Wednesday, March 06, 2002 - 2:51 pm: |
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I have an old k40 microphone without the cord -
can anyone give me the wiring pinout - cause the cord isn't even soldered inside the microphone so I'm not sure which wire goes where on the wiring strip inside the mic - I'll get a 5 or 6 wire mic cord from somewhere and wire it for my 10 meter mobile |
Jose22
| | Posted on Monday, May 13, 2002 - 9:56 pm: |
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I have located on K40 mic and 6 New In box k40-8 speech processor radios from local shop going out of business. He found them hid in back. The K40-8 is the large one not the small one. All boxes looked good. Wants me to make offer on all 6. What is a reasonable and fair offer for radios and the mic?
73's
Jose22 |
Jose22
| | Posted on Friday, May 17, 2002 - 12:51 pm: |
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707 You wanted k40 mic. The local that I am buying some of his old inventory, has 3 new in box k40 speech processor mics. He is asking 69.00 for them but as he is going out, has asked me to give him a price on all three. I am at least going to buy one for myself. Do you have any interest? let me know via-email and I will phone you with the details.
Jose22 |
Bigbob
| | Posted on Tuesday, June 25, 2002 - 9:01 pm: |
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Volume compression gives much better improvement on ssb than on am. |
67gto
| | Posted on Monday, December 01, 2003 - 9:59 am: |
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Is a Turner Plus Three Desk mic a compression mic?
I use one on my stock 2980 and everybody says my station is one of the best loud sounding stations around. They always ask me what tech did the tune on the radio.
THANKS,
G T O |
Gunnyhighway
New member
Username: Gunnyhighway
Post Number: 3
Registered: 3-2004
| | Posted on Wednesday, March 31, 2004 - 6:29 pm: |
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Jose22 I'd be interested in getting one of those mikes email me and we can talk about it. ammpmm@rcn.com |
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