EFJohnson 3000 SERIES >4 kHz, 0-200Hz, 1.5-4kHz, 200-500Hz, Above Data, 500-1500Hz, Above Data, Balance Quality, Balance Quality, Reflected Energy, Reflected Energy

TELEPHONE INTERFACE MODULE (TIM)

Figure 14-28 TELLABS 6132A/B TERMSET

8.A good way to measure the effectiveness of the balance across the Tellabs hybrid is to send a tone towards the CO and measure the energy reflected. A

clear way of accomplishing this is to establish an interconnect, then inject a 1 kHz tone at ±2 kHz modulation into the Receiver. With ±2 kHz of audio going in towards the CO, measure the amount reflected out of the Exciter with a communication monitor or measure pin 1 with respect to pin 7 on the

E&M card. A good balance, usually with the addi- tion of a 0.033 ∝F capacitor across the Tellabs balance network, will result in virtually nothing but data coming out of the Exciter. A very poor balance can send the Exciter to the limiter. A breakdown follows:

Reflected Energy	Balance Quality
Above Data
0-200 Hz	Great. No further
(Out of Exciter	adjustments are necessary.
Receive on E&M
0-16 mV RMS)
200-500 Hz	Good. Try to lower this by
(16-37 mV RMS)	placing additional capacitance
	(0.033 ∝F, non-polarized caps)
	in parallel with the Termset
	LSB cap. This system, how-

	ever, will sound good with no
	further adjustments.
500-1500 Hz	Poor. Definitely try to lower
(37-86 mV RMS)	this reflected energy by adding
	capacitance to the balance
	circuit.
1.5-4 kHz	Unusable. More energy is
(86 mV-1V RMS)	reflected than is sent into the
	CO. May be acceptable if all
	users are half-duplex. A full
	duplex radio will not work on
	this system.
Reflected Energy	Balance Quality
Above Data
>4 kHz	Reset the limiter on the
(>1V RMS)	Exciter. The balance is poor
	and a maladjusted audio
	limiter.

9.After the reflected is minimized, check the Tx level to the CO for -7 dBm.

10.Turn off the tone, but keep the call going.

11.Inject a 1 kHz tone onto Tip and Ring at the remote location. A good remote location would be the SMR operator's shop (vs the operator's site), or any CO exchange other than the one at the site. Inject the tone into Tip and Ring using a Telephone Test Set. Setup the remote location for a 1 kHz tone at -7 dBm (346 mV RMS, 978 mV P-P) on Tip and Ring at the remote location.

NOTE: If a remote location is not used for injecting onto Tip and Ring, interconnect and dispatch levels will likely be different. Typically, if audio is injected from a telephone line of the same CO exchange and the Exciter deviation set for ±2 kHz of audio, the same level injected into a line from a different exchange will result in less than ±2 kHz of audio from the Exciter. Injection can be done locally as long as the difference is made up by placing dispatch and interconnect calls and comparing the levels. Make up for differences using the Tellabs Termset dip switches.

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