Path: utzoo!telecom-request Date: Thu, 11 Apr 91 22:40 PDT From: Andy Jacobson Newsgroups: comp.dcom.telecom Subject: Re: Phone Audio to RCA Jack Message-ID: Organization: TELECOM Digest Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 287, Message 9 of 10 Lines: 36 In TD V.11 #279 James Blake said: > Has anyone ever come across a device which would allow one to take the > line level out from an RCA jack to a telephone line and to take the > audio from a phone to a RCA jack? If you're willing to consider a 1/4 inch jack for your audio source, there is of course the Ma Bell "QKP" "QKT' or "QKTBT" voice coupler arrangement. These little jobs were provided usually in a type 30 jack housing, or occasionally engineered with a 1/4 jack in the side of a reworked 500 type phone set. Primarily for radio stations for the ubiquitous "phone patch" so often used for call in shows and remote broadcasts, in most arrangements they were bridged off of the co line and were turned on/off by a switch on the side of the associated phone. The old ones consisted of little more than a transformer for isolation, a capacitor (to prevent passage of DC?) and a zenor to limit the line level (and of course a 1/4 inch jack). They were crude devices, producing a characteristic distortion and giving a poor signal level match for broadcasting two-way conversations. Later versions contained more circuitry removing the distortion. Most stations that can afford them use expensive and well engineered bridges from non-telco vendors that clean up the audio and match the signal level. Many of these devices are made to work with 1A2 equipment, and are designed to be hooked up to the CO or KSU line, entirely replacing the phone set. I don't remember the names of any of the manufacturers, but they are available from any broadcast supply house such as Allied (Harris) Broadcast Supply. Andy Jacobson or