General Purpose 4 Way Distribution Amplifiers DA1-4HL and DA1-4RFImportant Note: DA’s supplied after August 2105 may use Low Profile BNC sockets instead of standard height ones. The panel drilling details in the Manual (Fig 10) have been updated to give the correct dimensions for both standard (17mm) and LP (15mm) drill centres. If your kit uses LP sockets, there will be a note to confirm this in the package.

DA1-4HL/RF Manual – including circuit descriptions, typical performance, circuit diagrams and PCB overlays etc.
Drilling overlay for case  – for standard BNC sockets only – see above and refer to Fig 10 in Technical Manual.

See DA1-4HL Product Review on e-HamThe DA1_4 provides a 4 way split from a RF input signal from below 1MHz, and is usable up to around 1.8GHz. The two versions are intended for different applications, but are based around the same core splitter-amplifier:

• DA1-4HL is basically the same product as the earlier DA1-4L, providing a 4 way split for high level signals such as the +10dBm output of GPSDO’s. This new version does now include a 12MHz LPF.
• DA1-4RF has an extra front end amplifier stage, and is much better suited to distributing RF signals, such as antenna to multiple  receiver inputs etc. It is also useful as a line extender in paging system distribution. This version does not include the 10MHz LPF components as standard, but does have the option for either an internal 5 pole LPF or an off-board customer provided filter.
• Both versions now exclusively use right angled screened BNC connectors which mount directly to the PCB, and come with a DC power lead

DA1-4HL complete	DA1-4RF complete
Internal view of DA1-4RF – top side PCB	Internal view of DA1-4RF – lower side PCB

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Performance

Note that the following measurements were made on the older version of the DA1-4, but I have left them here as there is very little difference in the new versions and whilst they may no longer be precise, they will certainly remain typical of the product.

Thanks to the excellent test equipment available at Mid Atlantic States VHF Conference 2009, more detailed measurements have been possible than I can make in my workshop. Specifically, the ‘added’ phase noise of the unit, and the differential phase and gain at 10MHz (ie the difference in phase or gain between the output channels). The phase difference measured was +/- 0.4dB, and the variation in gain was +/- 0.05dB. These figures were taken on a R&S Network Analyser. The ‘added’ phase noise was measured on the R&S FSUP Signal Source Analyser, which has a built in 10MHz reference (also used as the DA input for the gain and phase measurements above).

In the graph below, there are two traces – the first (blue) was a capture of the phase noise of the source alone, while the second trace (black) was with the source run through the DA. As you can see, there is very little difference between the traces, indicating a very low added phase noise contribution from the DA.

Excess phase noise introduced by DA1-4L 

DA1-4 gain comparison from 10 to 1800MHz. Mkr at 1297MHz	Output phase variation at 10MHz

The gain measurements shown above are with 0dB attenuation configured in the module, and 0dBm nominal input level. For the LF version, the gain at 10MHz is approx 5dB per channel, dropping to approx -1dB per channel at 1.5GHz.

All unused outputs should be terminated in 50R for correct performance.

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