Dial-modem Low Speed ?

[drake]

Many times I find Desktop-PC’s without grounding and Owners complain a slow Dial-up connection.

Test:

My grounded Desktop-PC with an internal US-Robotics Modem runs normally at the speed 52 kbps .

Now, I’m disconnect the grounding, connect again, 36 kbps !

Conclusion:

All Power supplies in Desktop-PC are equipped with a Filter, Coil and two capacitors. (Eliminate the spikes, produced from switched Power supply, to spread to Power line). One Capacitor connected from “live” and one from “neutral” to Case.

Without grounding the capacitors divide the 240 VAC by 2, the Case from PC will be on 120 Volt AC.

With the Case, the Ground Reference to the environment and the Phone-Line is 120 VAC instead of 0. By startup a Dial-up connection the Modems find the Phone line noisy and switch down the speed.

To grounding a Desktop-PC is a MUST. (Older Notebook-PCs with 3-Pin Power connectors too).

To build grounding systems consult

http://www.thailandguru.com/cq-grounding.html

[francois]

hi'

basic good idea for any computer to be grounded ...

so the INTERNAL modem can get advantage of this ...

what about EXTERNAL modem, since they do not provide any grounded-plug?

I have a steady 45.2, so if grounded it could be running at more than 50 ...

can you tell me why this? : once I had a TOT line number very close to telephony-central, I got a regular 50.6 ...

now that I have moved, my line is a TT&T and further from central... I have "only" 45.2 !

I do think that the quality of the line and the location of it is the most important.

not much we can do with an external modem

cheers

francois

[drake]

Hi francois

Internal or external Modem – no difference.

With Shield- and Ground-pin from Comm- or USB-Port the reference potential is same.

The distance between PABX and Modem is one, bud not the biggest Problem (I’m 10km away from PABX).

The Cable quality is much more important.

Today, the Phonecompany’s use multiwire, twisted pair cable (black cable about 3cm diam.) as main distribution. Twisted pair Cable can handle higher frequency and is more immune against noise and magnetic fields.

This cable ending on the Street in a small aluminum-Box. After, a 2-wire black cable with a steel-carrier connect the small Box (over voltage protection) outside the House. This cable isn’t twisted-pair and over longer Distance a good antenna to receive noise, especially when it’s run in parallel to a power line. (my connection 10m).

The next problem is the house-wiring. The small white cable with 2 twisted pairs is OK. It should not fit in the same tube with the power-wiring.

Additional equipments like Fax or Phones connect to the same Phone line can be a problem (disconnect all and tray).

Good luck drake