Just experienced the same problem. No audio when transmitting using the MH-31 mic on my FT-857. Replaced the dynamic element with an electret, and all is good. Very much appreciate the excellent video!
Only found your chanel recently and I am loving the videos. Fantastic pace and very well explained. I cannot stop watching them, keep up the good work and I look forward to many more. Karl
What a fun repair! I really enjoyed this one. The mic modification was an interesting choice, but if you make the repair based on what you have in the toolbox, you might be forced to make this type of modification. Good video!
I hope when you open the radio, that you are not trying to fix someone else's mistakes. Hope you find a virgin circuit board. Well, now, don't even open up the radio. What an easy fix for audio. I've had to change out my mic on my old Kenwood 281a when I kept getting audio reports of motor boating. So, I ordered a new mic and that solved the problem. Looks like the "golden screwdriver" is at it again. Can you do a ring test on the element to see if it is gut? K9POW in eastern Tennessee
My way to check a mic element : on a CB, plug a speaker into the PA jack. This will check cord, switch and element. If no PA put your finger on element connection in mic and check for hum, or listen with signal tracer, or look at on scope or OUTPUT on multimeter or even look for some output on SSB. You can try to bring a dead one back by baking at 200 F. for a while. For a carbon mic, pound with a hammer. K4OF.
How do you know the values of the components to use? Is it just from experience? This is where I struggle. If a circuit diagram says 3900pf for a capacitor this is what I would try to fit but more experienced technicians would say “The value is not critical you can use almost anything”. What I need is a technician that could give me one to one help but unfortunately there are none in my area! So I will keep watching as many videos to give me the experience bit by bit. I do like the way that you explain things very clearly showing things step by step. It is very helpful. 73’s Lynton.
Peter, Great Video. I was a technical instructor teaching atomic particle accelerators for many years. I know how important it is to go slow and be very careful when teaching so EVERYONE understands. Keep up the good work. 73 ( Good Wishes ) David Robertson KD1NA PS Are you an amateur radio operator?
David Robertson Hi David, thank you so much for your comment. I'm glad that you like it. Yes, I fully agree with you it is important to go slow and very carefully. It might be boring for a professional but this channel is for HAM's and CB's as long they are interested in electronics. No I'm not a HAM operator even my whole life is and was HF radios, systems and what have we :-) 73
Nice. I just broke my radio. I have similar symptoms, but i have signal from mic in radio. Also modulation indicator is working. I have also carrier on AM and FM. I am going to try to repair, but yeeach...
Can you help me make modification for this MH31 by adding treble, mid and bass trimmers for adjusting the mic quality and of course using a condenser mic capsule.... ?
Your right about my age in Wiesbaden, my father was a military lawyer on The War Crimes. My German friends who escaped the Hitler Youth Train got me interested in radio. K4OF.
Peter, Thank you for ALL the great videos. So, I have the exact same issue with my HTX100. The MIC cartridge has failed. No audio on SSB.I am wondering how you came to use the 8.6k resistor in the modification. I have an 8volt supply at the MIC andCan use that. I saw another video where a 1k was used for an 8volt supply. So I'm confused as this was a similar modification.Thank you, ...t
+N3zjp Hi Tony, thanks for comment! Well the electret Mic cartridge have a wide range of operating voltage so these cartridge work from 1k up to 20k or more at 5-10 Volt. Best is to look into the technical data sheet for your cartridge to get the best value. But as I said this is not critical....
Kindly thing about Phantom power +48 Volt DC witch is common to supply Condenser mic in professional Audio mixer. Small number of resistor from 680 Ohm - 1.5 K,Ohm is suitable for DC supply up to 15 Volt. to have sensitivity approx -40 ~ -30 dB V/Pa.
In other words I do not have the skill or patients to do such great testing. Or would even know to change the part inside or what type is a close match. Very good work.
Thank you for the response. So using Ohm's Law, I have 8 volts feeding the condenser microphone with .0003 amps draw. I need a 26k of resistance? That seems high to me?Your thought? Or is my math wrong? ...t
+N3zjp Well as I said, the voltage range is very wide. Let's say from 1,5-10V and 300uA. We want to have approximate 4V drop at the resistor (or even less). That means take a resistor between 4,7K and 10K that should work.
Ready to tear my hair out having survived ten minutes of this well meaning - but incredibly s-l-o-w vid. Can't watch any more, sorry. When 1 word will do, it's better not to use 100 words young man!
Ian Gourlay Some of us need more explaination to understand. I for one appreciate the way he instructs. So many videos I have to keep going back over and over. With this pace I am fine. I am not up to speed like you must be. Jeff
great step by step explenation. but it was hair rasing english for me to much ja and "and hu" for me. i am dutch from birth but my english speaking is better then my dutch according to my former teachers. so yeah i think its not so hard to speak it correctly.
good day i am text ta3imd There is a problem with my yaesu ft857. Listening at 27 mhz (27,215 mhz) is fine, but the other station can hear me clearly while sending on 27,217, thank you 73
***** es werden in den nächsten WOchen zwei CB Geräte- Tests auch in Deutsch erscheinen und das 10m Gerät von Team ist ein Mix aus deutsch und englisch. Ansonsten haben ich viele englischsprachige Abos, die leider nix mit deutsch anfangen können...
Just experienced the same problem. No audio when transmitting using the MH-31 mic on my FT-857. Replaced the dynamic element with an electret, and all is good. Very much appreciate the excellent video!
Only found your chanel recently and I am loving the videos. Fantastic pace and very well explained. I cannot stop watching them, keep up the good work and I look forward to many more. Karl
Karl Fell Thanks for you feed back. Great that you like the pace and the content.
This is a brilliant video, you explain the theory and practice in an easy to understand manner.
Thank you.and best wishes, shaun.
+shaun49 Thank you very much for the feed-back Shaun. All the best
Really Great repair video.
I learned about checking a microphone.
Great work modifying the circuit.
Thanks for making these videos.
Grant Fullen You can play with the capacities to optimise for your voice. Thank you.
Peter, another great video. I have learned so much from you. Thank you for your contributions and I am looking forward to watching more.
Jeff
Jeff Thomas Hi Jeff, I'm glad that you like my videos and thanks for feed-back! 73
Interesting repair! Nicely fixed again.👍
Thank you very much. This video is wonderful. You are a great teacher. Thank you, again!
Excellent video easy to follow. Look forward to more videos from you 👍👍
Glad that you like it 73
Thanks again for taking the time to enlighten us,great work.
Chrysiotis you are welcome. Thanks for your feed back!
What a fun repair! I really enjoyed this one. The mic modification was an interesting choice, but if you make the repair based on what you have in the toolbox, you might be forced to make this type of modification. Good video!
Brad Morris Well the mic mod makes sense due to the fact that the original mic is not that good. Thanks for feed-back. 73
I hope when you open the radio, that you are not trying to fix someone else's mistakes. Hope you find a virgin circuit board. Well, now, don't even open up the radio. What an easy fix for audio. I've had to change out my mic on my old Kenwood 281a when I kept getting audio reports of motor boating. So, I ordered a new mic and that solved the problem. Looks like the "golden screwdriver" is at it again. Can you do a ring test on the element to see if it is gut? K9POW in eastern Tennessee
Another great video
My way to check a mic element : on a CB, plug a speaker into the PA jack. This will check cord, switch and element. If no PA put your
finger on element connection in mic and check for hum, or listen with signal tracer, or look at on scope or OUTPUT on multimeter or even look for some output on SSB. You can try to bring a dead one back by baking at 200 F. for a while. For a carbon mic, pound with a hammer.
K4OF.
BOB RENFRO Hi Bob, very nice way to test. Thanks for your contribution. 73
Fantastic!! Just what I was looking for...tnx for sharing...
budleyca1 Thanks! Great that it fits into your needs.
did mine on the 817 and 991 and i loved it kg6mn
How do you know the values of the components to use? Is it just from experience? This is where I struggle. If a circuit diagram says 3900pf for a capacitor this is what I would try to fit but more experienced technicians would say “The value is not critical you can use almost anything”. What I need is a technician that could give me one to one help but unfortunately there are none in my area! So I will keep watching as many videos to give me the experience bit by bit.
I do like the way that you explain things very clearly showing things step by step. It is very helpful. 73’s Lynton.
This is another great video as always. Thanks much
Satellite_Guy Thanks for you feed-back and attention.
Peter, Great Video. I was a technical instructor teaching atomic particle accelerators for many years. I know how important it is to go slow and be very careful when teaching so EVERYONE understands. Keep up the good work.
73 ( Good Wishes ) David Robertson KD1NA PS Are you an amateur radio operator?
David Robertson Hi David, thank you so much for your comment. I'm glad that you like it. Yes, I fully agree with you it is important to go slow and very carefully. It might be boring for a professional but this channel is for HAM's and CB's as long they are interested in electronics. No I'm not a HAM operator even my whole life is and was HF radios, systems and what have we :-) 73
Nice. I just broke my radio. I have similar symptoms, but i have signal from mic in radio. Also modulation indicator is working. I have also carrier on AM and FM. I am going to try to repair, but yeeach...
Have you had any thought on how to record the Rx and Tx without using two recorders? Have you seen an elegant way to record these audios? thx.
sehr schoen erklaert, danke. can you explain the position and polarity of the two capacitors in relation to the +5v supply please? thanks
Thanks for the video ..More really good advice.
charlieoscar09 Thanks for watching!
Can you help me make modification for this MH31 by adding treble, mid and bass trimmers for adjusting the mic quality and of course using a condenser mic capsule.... ?
super quick fix but soo interesting
Thanks for watching! All the best Cheers
Zeproo
Your right about my age in Wiesbaden, my father was a military lawyer on The War Crimes. My German friends who escaped the Hitler Youth Train
got me interested in radio.
K4OF.
BOB RENFRO Ah okay I see, you are a real witness of this horror time period.
Those darn RJ45 connectors ar a total dog unplug anf plug back in a few times usually cures that one
What about the ALC mod for this radio ?
Peter, Thank you for ALL the great videos.
So, I have the exact same issue with my HTX100. The MIC cartridge has failed. No audio on SSB.I am wondering how you came to use the 8.6k resistor in the modification. I have an 8volt supply at the MIC andCan use that. I saw another video where a 1k was used for an 8volt supply. So I'm confused as this was a similar modification.Thank you,
...t
+N3zjp Hi Tony, thanks for comment! Well the electret Mic cartridge have a wide range of operating voltage so these cartridge work from 1k up to 20k or more at 5-10 Volt. Best is to look into the technical data sheet for your cartridge to get the best value. But as I said this is not critical....
Kindly thing about Phantom power +48 Volt DC witch is common to supply Condenser mic in professional Audio mixer.
Small number of resistor from 680 Ohm - 1.5 K,Ohm is suitable for DC supply up to 15 Volt. to have sensitivity approx -40 ~ -30 dB V/Pa.
Great Video. But sorry to say I would have tossed the mic in the trash 10 mins into the video. Without all those tests. Always have a spare mic.
bluesman71 HaHa never mind. I see your point.. This channel is for all the HAMs and CB'ers who like to do handicrafts... :-)
In other words I do not have the skill or patients to do such great testing. Or would even know to change the part inside or what type is a close match. Very good work.
would you do another one of these ? if i send mine to you ? is it cost effective ?
Thank you for the response. So using Ohm's Law, I have 8 volts feeding the condenser microphone with .0003 amps draw. I need a 26k of resistance? That seems high to me?Your thought? Or is my math wrong?
...t
+N3zjp Well as I said, the voltage range is very wide. Let's say from 1,5-10V and 300uA. We want to have approximate 4V drop at the resistor (or even less). That means take a resistor between 4,7K and 10K that should work.
could have skipped about 45 min. good video
James skippinhopper well, as advanced technician yes, but as beginner you need a bit more back ground :-) Thanks for feed-back 73
Ready to tear my hair out having survived ten minutes of this well meaning - but incredibly s-l-o-w vid. Can't watch any more, sorry. When 1 word will do, it's better not to use 100 words young man!
Ian Gourlay Some of us need more explaination to understand. I for one appreciate the way he instructs. So many videos I have to keep going back over and over. With this pace I am fine. I am not up to speed like you must be. Jeff
great step by step explenation. but it was hair rasing english for me to much ja and "and hu" for me. i am dutch from birth but my english speaking is better then my dutch according to my former teachers. so yeah i think its not so hard to speak it correctly.
iv just today had the same fault on same Mic
good day i am text ta3imd
There is a problem with my yaesu ft857. Listening at 27 mhz (27,215 mhz) is fine, but the other station can hear me clearly while sending on 27,217, thank you 73
Super erklärt nur das Englisch ist gewöhnungsbedürftig, nicht böse sein^^
***** Hi, vielen Dank für's feed-back! Nein bin nicht böse, man muss auch seine Schwächen kennen :-)
Wäre toll wenn du mal paar Videos auf Deutsch machen könntest lg.
***** es werden in den nächsten WOchen zwei CB Geräte- Tests auch in Deutsch erscheinen und das 10m Gerät von Team ist ein Mix aus deutsch und englisch. Ansonsten haben ich viele englischsprachige Abos, die leider nix mit deutsch anfangen können...
super ich freue mich schon :)
To much mods on old mike cheaper to buy new power mike