[ICOM] 756Pro and Compression

[Larry Young]

Roger: Try the Icom hand mike and see if the hum goes away. If this problem is happening , and you are using the hand mike, does the noise disappear when you turn off the compression and lower the mike gain?
Larry K4LXV

--- On Fri, 11/19/10, Roger (K8RI) <k8ri at rogerhalstead.com> wrote:

From: Roger (K8RI) <k8ri at rogerhalstead.com>
Subject: Re: [ICOM] 756Pro and Compression
To: icom at mailman.qth.net
Date: Friday, November 19, 2010, 8:01 PM

Sorry about the late reply, but they changed Thunderbird to use the 
default address unless you tell in otherwise.  It used to default to the 
address to which the mail being answered was sent and after this many 
years "I default" to the old way of using it.

On 11/14/2010 11:00 PM, Larry Young wrote:
> Roger; Try the radio and amp together with the computer lines 
> disconnected from the radio. Plug in a set of headphones and listen to 
> the radio in the monitor mode.If clean reconnect the computer and 
> retest. Also, is all Ok with the output into a dummy load? Try one 
> thing at a time and slowly add stuff back to determine at what step 
> things are going awry.
> Larry K4LXV.
So far I've ruled out RF feedback and it makes no difference whether the 
computer is hooked to the CI-V interface via serial cable or not. BTW 
serial is something sadly lacking on most of today's computers.  I 
happen to have a 3.2 Gig quad core Athlon on a motherboard that has a 
serial port. I also happened to have a couple of PCI serial adapter 
cards with 4 ports. Two internal and two external.

Also it doesn't seem to matter if it's on the air or hooked to the DL-5K 
dummy load, through the amp or not.

One thing that has shown up it an AC hum, much like the pin one problem 
I fixed earlier. It's possible a solder joint and cable connection that 
need redoing. As I said earlier, this is something that just popped up 
recently. This isn't the distortion, or compression problem. If I reach 
up and put my hand on the metal mike connector, or any grounded metal in 
the station such as the amp, tuner, or even dummy load cabinets the hum 
goes away, just as it did with the pin one problem.

Another fault I discovered was the "Amphenol" N connector at the patch 
panel had separated. Only the coax pressure was holding in it to make 
contact. The threaded barrel had come off the connector.

I need to get it hooked up with a headset or a headset through the 
computer to the audio card.\

So I've found some problems but not the original compressor problem.

73

Roger (K8RI)
> --- On Sun, 11/14/10, Roger (K8RI)<k8ri at rogerhalstead.com>  wrote:
>
> From: Roger (K8RI)<k8ri at rogerhalstead.com>
> Subject: [ICOM] 756Pro and Compression
> To: Icom at mailman.qth.net
> Date: Sunday, November 14, 2010, 7:02 PM
>
> I purchased my 756 Pro new not long after they came out and never had
> any complaints on SSB or CW other than a pin 1 problem. I did change the
> mike grounding as it was picking up the 60 fields in the room.  I did
> have to give up some of the mike functions, but it cured that problem. 
> HOWEVER something has changed recently.
>
> I always ran a fair amount of compression with my voice characteristics
> and received good reports.  About 9 months ago I added a new Emtron
> DX-2sp to replace my old Alpha 76A.  Again, with the same settings for
> the mike gain, compression, and RF drive I was receiving good reports.
> One DX station even commented several times about the good quality of
> the signal.
----
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