[GreenKeys] USB-teletype adapter with ASR33 question

Tue Jun 7 18:37:55 EDT 2016

The receive side of the 33 wants 20MA unless you change a couple of things in the UCC-6 to 60MA. 

Wayne 

----- Original Message -----

From: "Lester Veenstra" <m0ycm at veenstras.com> 
To: epvgk at limpoc.com 
Cc: greenkeys at mailman.qth.net, "Julien Scrofani" <julien.scrofani at gmail.com> 
Sent: Tuesday, June 7, 2016 5:24:49 PM 
Subject: Re: [GreenKeys] USB-teletype adapter with ASR33 question 

Transmit loop is dry contacts so it does not care. The 20/60 ma question is 
a matter internal to the USB adaptor. 

Lester B Veenstra MØYCM K1YCM W8YCM 
lester at veenstras.com 

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-----Original Message----- 
From: epvgk at limpoc.com [mailto:epvgk at limpoc.com] 
Sent: Tuesday, June 07, 2016 5:01 PM 
To: Lester Veenstra 
Cc: 'Julien Scrofani'; greenkeys at mailman.qth.net 
Subject: Re: [GreenKeys] USB-teletype adapter with ASR33 question 

On Tue, Jun 07, 2016 at 04:58:57PM -0400, Lester Veenstra wrote: 
> Put a low voltage power supply and current limiting resistor (No need for 
130 V in this case) in series with the ASR TX contacts and the USB input. 
Set up the voltage/resister for 60 MA and you should be in business. Before 
you start, put an ohm meter across the ASR TX contacts and you should see a 
fairly low resistance. When typing you should see the resistance go up. 

He's using a 33, shouldn't it be 20mA? (the usb adapter won't care, but the 
tty 
might?) 

eric 

> 
> 
> 
> Lester B Veenstra M??YCM K1YCM W8YCM 
> 
> <mailto:lester at veenstras.com> lester at veenstras.com 
> 
> 
> 
> Physical and US Postal Addresses 
> 
> 5 Shrine Club Drive (Physical) 
> 
> 452 Stable Ln (RFD USPS Mail) 
> 
> Keyser WV 26726 
> 
> GPS: 39.336826 N 78.982287 W (Google) 
> 
> GPS: 39.33682 N 78.9823741 W (GPSDO) 
> 
> 
> 
> 
> 
> Telephones: 
> 
> Home: +1-304-289-6057 
> 
> US cell +1-304-790-9192 
> 
> UK cell +44-(0)7849-248-749 
> 
> Guam Cell: +1-671-929-8141 
> 
> Jamaica: +1-876-456-8898 
> 
> 
> 
> This e-mail and any documents attached hereto contain confidential or 
> privileged information. The information is intended to be for use only by 
the individual or entity to whom they are addressed. If you are not the 
intended recipient or the person responsible for delivering the e-mail to 
the intended recipient, be aware that any disclosure, copying, distribution 
or use of the contents of this e-mail or any documents attached hereto is 
prohibited. 
> 
> 
> 
> From: GreenKeys [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of 
Julien Scrofani 
> Sent: Tuesday, June 07, 2016 4:29 PM 
> To: greenkeys at mailman.qth.net 
> Subject: [GreenKeys] USB-teletype adapter with ASR33 question 
> 
> 
> 
> Hi all, 
> 
> 
> 
> I bought Eric's usb adapter to link my asr33 tty to a PC. 
> 
> As is, I can transfer from PC to the tty but I cannot transmit in the 
other way, tty toward PC. 
> 
> 
> 
> I know that current loops are needed. 
> 
> It works for one way without additionnal power supply, so maybe my 33 has 
an internal current loop. My problem is I'm not able to determine if it's 
really the case and I don't how to add one if I need to. 
> 
> 
> 
> I have no electronic knowledge at all, sorry if my question is a dummy one 
! 
> 
> Thank you in advance. 
> 
> 
> 
> Bests regards, 
> 
> Julien 
> 

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