Networking GB3JV!

GB3JV progress is being made! I’m expecting the new Rx antenna to be delivered this week, so then I should be ready to get the contractors in for the antenna installation!

Modern Repeaters need a connection to the Internet, so I’ve just ordered a Cisco Meraki Z1 Teleworker “Gateway Router” to form a LAN-LAN VPN Connection to the home QTH from the repeater site. The Z1 is entry-level product and only supports 10Mb/s VPN throughput, but this will be quite adequate for the remote management of the repeater system. The heart of the management system will be an Intel “NUC” running Ubuntu 18.04, Home Assistant and VLC for the media streaming. I might add some interesting logic and web pages later on.

As an alternative for the networking back to the home QTH I was in two minds about setting up a 5GHz (license free) link vs. LTE cellular. For now I’ve opted for LTE cellular, but I might go for the fixed 5GHz link at a later date. For now LTE cellular is the most simple method with minimal work and risk.

The network operator is “SMARTY” (a new brand owned by H3G). It’s a bare bones product but provides unlimited everything (Data, Calls & Texts, EU Roaming etc.) and a fairly decent data performance and a 30-day contract with no significant “fair usage” policies, at least from what I can see. I’ve managed to get the -25% for life discounted introductory offer, so I’m paying £18.50/month, including the “Vodka and Tonic”. If you are interested and want a £10 Amazon voucher and a month’s free rental this is the referral link, that will also get me a free month to offset the cost of the repeater networking.

The repeater site is line-of-sight to the local cellular tower, with a sector antenna pointing straight at us about 500 yards away, so the connections should (hopefully) be reliable. If you want to get a cellular internet connection to your repeater site, I’d recommend looking at the Cisco RV130 or RV130W (Wireless) teleworker gateway. These firewall/routers have L2TP and IPSEC VPN capability, 4 LAN ports, a WAN port and a USB socket for a Cellular Modem. They are easy to set up using a GUI (you don’t need to be a CCIE and familiar with the IOS command line!), they are also end of sale, so can be picked up brand new for around £100, or even less. I’ve used the Cisco Meraki Z1 because I can easily add it to my existing Meraki home network and firewall and I get the benefit of the cloud management and the annual license of £20 includes next day hardware replacement, the RV130 is probably a better alternative if you’ve not already got a Cisco Meraki network.

Best Regards, Justin G8YTZ

BATC MiniTiouner Case

Want to give your BATC MiniTiouner a professional finish? I’m pleased to announce that a anodised aluminium front and rear panel kit will be available for shipping on 1st July to fit the Hammond 1455N1202 Enclosure. The kit includes:

Front Panel (as shown), Rear Panel including cut-out for an OLED display, OLED Display and pre-made cables.

Front Panel (Alpha, final version has spelling mistakes corrected and additional legends)

BMW i3 Electric Car blog

I have just uploaded the first in a series of videos about ordering and the ownership experience of the BMW i3 Range Extended electric car. A link to the Youtube playlist is below.

Justin G8YTZ


Press Release: GB3JV – NoV Received

Petts Wood, 3rd June 2019

Justin G8YTZ is delighted to announce that the NoV has been issued approving a new Digital Amateur TV Repeater located in Petts wood, Kent. The repeater output will be on 3404MHz, the input frequencies will be confirmed later. The transmitting antenna is a slot type made by Bert Modderman PE1RKI and the receive antennas are WiMO planar types. Justin hopes to have the repeater on test transmission in August 2019.

The Digital TV repeater is based on SR-Systems modules will initially use the bandwidth efficient DVB-S2 format with a future upgrade path to DVB-S-X2 when suitable receiving equipment is freely available. The 8PSK modulation format will be used @ 2000 kS/s; though more complicated to transmit, does have the advantage of requiring simple receiving equipment. A DVB-S2 Satellite Receiver, or better still a BATC Minitiouner, a small dish and an C-Band LNB is all you need to receive GB3JV and therefore encouraging the up-take of Amateur Television. Coverage predictions show reception possibilities across the heavily populated area of South-East & East London as well as parts of Essex.

If you are interested in Amateur TV, why not join the British Amateur TV Club and receive the excellent quarterly club magazine? Details at

Justin would especially like to thank Noel Matthews G8GTZ for his help in obtaining the license NoV for this exciting new repeater, Bob Dunne for his help in acquiring the site and members of the Bromley & Distract Amateur Radio Society, Gareth G4XAT, Andy G4WGZ, John, G8MNY for technical construction, advice and support as well as the site owners who made the whole thing possible.

Information and updates are published on the repeater web site  

Justin G8YTZ

Next Generation DATV Repeater

    Next generation TV Repeater Development: Available for delivery from June 2013

I am currently working on a future proof repeater solution. I should have the working prototype (output 70—2200MHz) during April and a 3.4GHz prototype in a case during May. This product will be ideal for Analogue repeater keepers who want to convert to Digital. The entire repeater (driver Transmitter, receivers and multiplexers) will be contained within a 1U 19”chassis. Just add your own Rx filters and Power amplifier(s). The output is DVB-S2 (also DVB-S software selectable) or DVB-T 145-2200MHz (1mW) and with an option for 3.4GHz 1mW or 10GHz (1mW or 200mW on 10GHz) with up converter contained within the chassis (1U).
Here are some of the key and more interesting features:

– With DVB-S2 you can switch on the PILOTS and then the re-lock time is under 1 second, it also supports H264, or MPEG2 depending on what is sent by the user!
– You can select QPSK or 8PSK for an even smaller BW for the same bit rate giving the following bandwidth example:
Total 6Mb/s for programme using the following settings:
DVB-S2; 8PSK; 3/5FEC; Pilots=ON; RollOFF=0.25;
(6.95Mb/s with 5MHz spectrum bandwidth)

There are three inputs and two programme outputs, so two people can use the repeater at the same time! Here is an example configuration:

Input 1 (Programme 1) : Has an auto switch, H264 (HDMI) encoder for a sustaining programme feed from a local media player or test card generator, but when RX lock occurs on the receiver then the Transport Stream switches to the Rx so Programme 1 is then in repeater mode.

Input 2 (Programme 2): The second receiver can be connected to the second TS input, or you can specify a second TS switcher, so you can switch between the two DVBS/S2 receivers, perhaps one is 23cm and one has a down converter from 10GHz or between two receive antennas on the same band set to different frequencies. The lock indicator on the Rx causes the TS switch to switch and with priority on one Rx should there be a lock on both inputs, or configure both as a pseudo-diversity receiver driven from two Rx antennas.
This is an example configuration that I am using for the prototype, but all of the above is customisable to your exact requirements! Number of receivers, inputs, outputs etc. Remote control is via the RS-232 interface (modem etc), but I am also experimenting with a web control option.

I can also add an MPEG2 encoder for an external analogue Rx input if required as an alternative or an addition to the H264 encoder.

Example RF Inputs:
DVB-S/S2 23cm, dual receiver, (3Mb/s, 4MHz bandwidth) and output is according to H264 or MPEG2 whatever you send to it.
DVB-T 70cm in, 3Mb/s, 2MHz BW, QAM16; 2/3FEC; 1/4 Guard interval
Drop me a line if you are interested in discussing all the options.

Justin G8YTZ

Case Kits

I’ve had a few people who already have SR-Systems modules ask me if I can just provide the cases for retro-fit. Yes I can, but please be aware that the case is only compatible with the Display + Key v3 I2C interface board and not the Minikey unit supplied with the standard SR “Ham Set”. I can provide the case with mounting hardware for either the Tx or Rx (only difference is the rear panel) for £99 including VAT and shipping to a European addresses. The case kit includes all the mounting hardware down to the rubber feet.

Justin G8YTZ


Finally G8YTZ has a new web home

You can view our videos on our Digital TV transmitter & receiver,  view our image gallery too and even get in touch if you have a question about our box-of-tricks