Specifications

3.4 Use with RPU Equipment
It is quite feasible to use the DAI-2 with communications links other than telephone lines. For example, the control
and switching capabilities of the DAI-2 often can be useful during remotes using a UHF Remote Pickup Unit (RPU).
The audio output of the RPU receiver should be adjusted to a level between -30 dBm and 0 dBm and then fed to the
LINE jack on the DAI-2. Bring the DAI-2 online the the manual connect control--either from the front panel
pushbutton or the logic-level input.
It is easy to construct an extremely versatile system that allows two communications links to be used with the DAI-2.
Either a telephone line or the output of the RPU receiver can be connected to the DAI-2 using the squelch relay in an
RPU receiver to control a DPDT relay as shown in Figure 3.5.
Figure 3.5; Using both and RPU and telephone line with the DAI-2
The DAI-2 contains an internal 4.5 kHz low-pass filter. This will not limit the bandwidth of audio coming from the
telephone line but it will restrict bandwidth of the audio coming from the RPU. This is usually not a problem for voice
broadcasts, but it may be an issue for music broadcasts.
DTMF tones are used to control the DAI-2 when using a telephone line. DTMF tones can be generated by simple tone-
dialers but these devices may require modification to obtain the necessary audio connection.
3.5 RF Interference
The DAI-2 is typically a studio device so there have been few reported RF problems with this device. However, since
it can be installed at a transmitter site, a few suggestions on preventing RF interference are in order. The DAI-2 is
designed with bypass caps and suitable RF protection on the telephone line for most installations. However, extreme
conditions exist that require additional external filtering to obtain reliable operation. Extreme conditions are rare but
these problems can be overcome by a combination of one or more of the following remedies:
• Install an RF filter before the "Line" jack near the DAI-2
• Loop the ribbon cable several times through a ferrite core at each end
Telephone line RF filters can be obtained through a wholesale distributor or telephone products. Suttle Apparatus is
one manufacturer of these devices. They can be reached at [phone] or http://www.suttleonline.com. Be sure
to get an RF filter and not simply a spike protector.
DAI-2 Installation page 3. 6