As we all know, properly installing and maintaining repeater systems is not only a time-consuming effort, but requires some pretty sophisticated equipment in order to do it to commercial standards. Yes – many folks go the way of McGyver either because of lack of access to the proper tools, or lack of funds – and most do a respectable job. But not having the right tools just makes it harder, more time consuming and more prone to errors.

Take the tuning of duplexers as an example. There are those who do it with 2 handheld radios and a step-attenuator and just “listen” for differences in signal clarity. I have known (and worked with) guys who insist that this works, but invariably this leads to off-tuning of the cavity filters and potential intermod due to the passing of undesired signals. The right way is to use a Spectrum Analyzer with a Tracking Generator and a good quality Return-Loss-Bridge like the Eagle RLB-150x4a which will go to 2ghz.

The other case is in the verification of Feed-lines and Antennas. Many of us use the Antenna Analyzers from MFJ or equivalents – darn good devices for what they cost. But in the commercial world, we are required to sweep with units which operate with Frequency Domain Reflectometry (FDR)- a technology which has been around for about 15 years and which measures Return Loss using specific frequencies (versus Time Domain Reflectometry or TDR, which uses DC). The FDR technique is MUCH more accurate and allows us to sweep antennas which are in close proximity to other transmitting systems which are currently in operation.

The current leaders in manufacturing commercial-standard Antenna/Cable Analyzers are Anritsu and Agilent (formerly HP Test and Measurement). The Anritsu SiteMaster has been the mainstay of the Cellular Site Antenna/Cable analysis for many years – with most Cell companies having required “Anritsu Certification” by their contract installers of feed-line and antennas. Agilent has stormed on the scene in the last 5 years with (arguably) a better unit.

We have had the Anritsu SiteMaster S113C for over 5 years now, having purchased it second-hand from a fellow commercial services company. It has been and continues to be a workhorse, but it only sweeps to 1.8ghz – not enough to diagnose the newer technology signals which are above 2ghz (like WiFi, WiMax and some of the higher Amateur bands). It is also difficult to read in the dark due to the lack of back-lit keys. Therefore, we just purchased a new Agilent N9330B which will sweep to 4ghz and are putting it into service. The N9330B gives us even more recording capability, so that we can store sweep information and analyze it when we return to the lab – and include those sweeps into our systems documentation (see our post on April-11 and May-20).

So we welcome the Agilent N9330B to it’s new home – may it provide us years of faithful service and enable us to spot problems with our transmission systems WELL before they become service interruptions..!!