Versatile analogue repeater
Updated: Nov 27, 2023
Although I have written about the Yaesu DR-2 analogue & digital rack mount repeater, with more to come and some material on the DR-1. This post is primarily about a budget repeater by Tait that was aimed at Land Mobile or PMR, oversimplifying a higher part of the VHF band. You can check the specific bands available with this license below in the links. Increasingly we want interoperability with Search & Rescue teams linking PTT or POC radio to an analogue system (Digital if lucky) & realtime GPS, It really does depend on your budget.
This is a Tait 2000 analogue VHF repeater system that can be programmed for Amateur use or Land mobile. Old, yes and second hand, but still a very useful tool & as you can see compact. If you're unfamiliar with PMR or Land mobile, then this may be slightly different. Analogue repeaters are still a very useful and a prevalent communications tool. There are
differences in how you apply for a business license with the forms linked below, as well as a link to the descriptions of licenses that come under the business category. You’ll find they climb in complexity of form filling due to the nature of grid defined areas and frequencies as these areas can be quite big. Business light, the easiest to apply for covers a range of frequencies you can see listed further down. Essentially 5 watt handheld use on the given frequencies, currently an online application of £75 for five years. Business ‘Site’ light is five years at the same price, but this is linked to a factory or location with an antenna providing 2 watts ERP 15m in the air. The ‘Technically assigned’ license is defined by grid square as a coverage area on a given or multiple frequencies, ranging from £75 to £1500. Finally the ‘Area defined’’ license is an exclusive 50km map square or bigger area and a frequency with facility of duplex operation.
This little unit boasts all the normal functions including split frequency, CTCSS, Compander, data functionality, along with a host of practical functions...including 'trunking' if you want to. You are only limited by your imagination as the budget for second hand gear can be significantly less than for say a DR-2, with many ham repeaters still analogue using similar technology. This one is business site light, but with a NoV is equally programmable for VHF ham band.
As you can see this one comprises from bottom to top of a dedicated power supply, control head, receiver and transmitter, they are bolted together using a Tait din style mount for each radio. It can be slid out of it's 'shelf' with a key. Tait legacy software available on the net will program the radios one by one. These radios are powered by finals that will give you up to 20 watts, however with a little know how, can be adjusted anywhere in between on a pot located on the board, likewise other features can be tweaked with the on board pots. This due to their age and having visible components and not surface mount.
Operating a split frequency will require a cavity to seperate RX & TX signals on an antenna system, and if you're not operating the unit at high power then a mobile cavity unit will suffice. Better longevity will always follow this practice of turning down the wick. Mobile cavities come in a range of bands and ideally close to a 5 mhz split is safe. These are small cavities and you don't want to wreck your transmitter. Running a VHF ham repeater in the UK on the standard split requires much bigger cavities, expense and work to keep the Transmitter happy.
Operating a split frequency will require a cavity to separate RX & TX signals on an antenna system, and if you're not operating the unit at high power then a mobile cavity unit will suffice. Better longevity will always follow this practice of turning down the wick. Mobile cavities come in a range of bands and ideally close to a 5 mhz split is safe. These are small cavities and you don't want to wreck your transmitter. Running a VHF ham repeater in the UK on the standard split requires much bigger cavities, expense and work to keep the Transmitter happy. Although not the most difficult of skills to master, it is worth taking your time to understand the process of tuning cavities. You have a pass band and a notch, the notch removes whichever is your unwanted frequency, the deeper the notch and the more precise the pass band, the better the duplexer will separate your frequencies. I'll include a really good link to a Youtube video demonstrating this nicely using a Nano VNA, of course there are plenty more to look at. If you look closely at the photo the cavities are adjusted by means of the threaded bolt at the top, in this case 3 cavities for each of TX and RX frequencies. Larger cavities have more adjustment & better separation. However if tuned correctly for low power operations you can get passable results with care.
Antenna wise, again check your specific frequency band. The Panorama brand does some discreet full power base (BSV series) and mobile (AFHB series) antennas. Sirio has a range of which the SPO-150 is a good example. These are for the part of the VHF band above the ham band, also do look at dual or quad folded dipoles. Budget will as always be key and for a low cost tip, always check out the Sharman range. Sharmans AH-50 is a cracking £60 vertical.
My mentor used to say height is mite, and to be fair he also used to say that range was as far as the eye could see, or the first tree. Of course all of this effort can be carelessly wasted with the wrong choice of coax. Nuff said.
https://secure.ofcom.org.uk/busrad/apply?start#
