[Milsurplus] grc106 low audio

[Ray Fantini]

Surprisingly the 600 Ohm audio input has the microphone input connected to it via the decoupling network for the microphone. So you can pump audio in that way. When using the MD522 it processes audio separate from the transceiver and sends it to the transceiver thru that line.  The MD522 can depending on mode pass voice or run in a TTY/Voice mode where it limits low frequency response on the microphone channel.
May want to look at your carrier level in AM and see what that is with no modulation. Perhaps that's why people think it's not loud in AM? Although its only generating USB and carrier in AM unless you're listening on a good radio or one of those SDR things most people don't realize it's just carrier and USB only with no LSB in AM, CHU on 7.85 has been USB+ carrier for years now and no one complains about them.

Ray F/KA3EKH

-----Original Message-----
From: comcast [mailto:kg2bz at comcast.net] 
Sent: Tuesday, April 17, 2018 9:39 AM
To: Ray Fantini <RAFANTINI at salisbury.edu>
Cc: mrca at mailman.qth.net; milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] grc106 low audio

ray
audio seems ok from usb based on a contact on 20m. the carrier meter and power out meter give me good swings upward. on a night contact on 3885 using ame i had to shout into the h33 for decent audio. i tried 2 different h33s one mic was totally dead. both swings are the same with either than h33 or the motorola palm mic. i did notice on the 34 manual there are 2 audio inputs 50 ohm and600 ohm into the RT. could that be for the md522 or a dynamic mic input?
jeff

Sent from my iPhone

> On Apr 17, 2018, at 9:30 AM, Ray Fantini <RAFANTINI at salisbury.edu> wrote:
> 
> 1A5 the transmitter IF/Audio section takes care of all the audio issues with that transceiver. It has a AGC system that keeps you from overdriving the radio along with a bias network that powers the microphone from the +20 volt bus.  You can use any high output device to drive the audio input being it was designed to receive the high level output of the H-33 that's capable of producing huge levels of audio when working correctly.
> The key thing there is it has to be working correctly and that's the biggest problem because most H-33 handsets I have used have dead microphone elements. 
> The weird thing is that is a SSB only transceiver. In AM mode you are just running USB with a carrier and in USB the audio level controls the carrier level so are the comments from running SSB or AM?  A good microphone will result in good action on the carrier level meter, how is that looking when you transmit? I can loan you another 1A5 to try if you think there is an issue with its audio. There is always a possibility that something like one of the interstage capacitors is going south although I don't think I ever saw one fail. Also you may want to stay away from having too sensitive a microphone with all the noise the amplifier generates!
> 
> Ray F/KA3EKH
> 
> 
> -----Original Message-----
> From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman..qth.net] On Behalf Of comcast
> Sent: Monday, April 16, 2018 6:34 PM
> To: mrca at mailman.qth.net; milsurplus at mailman.qth.net
> Subject: [Milsurplus] grc106 low audio
> 
> folks i have a grc106 working as a fixed station using ame mode i have been receiving reports of low audio. i made a mike adapter using a motorola mocom70 mic and also the older style base station mike.  compared to the h33 handset ( am ive tried several different h33s) audio no better. any recommendations for a carbon mike with gain?   i have  an electrovoice 602t aviation hand mike which has a built in amp and am thinking about using that. 
> thanks
> jeff
> 
> Sent from my iPhone
> ______________________________________________________________