Sunday, 17 December 2017

Homebrewing

of both varieties!

Its been quite a while since I did much radio, so today I finally shifted the heap of spares and other bits off of the shack desk. A quick tune about showed the HF propagation to be next to nowt, so instead contented myself with finally working out the best way to connect my keyer and twin paddle key up!


This involved making up a custom cable, allowing me to connect the phono connector keying output on the keyer, to the screw terminal posts on my Kent straight key. This was a bit confusing at first, as the HF transceiver would go into Tx and stay transmitting! This turned out to be due to having the key line inverted!

A handful of test transmissions later and the keying is up and running. Ive also added four rubber feet to the twin paddle, which helps stop it sliding around the desk!

The other homebrewing ive been doing, was to start a 6 liter batch of Turbo Cider, and a tropical WOW wine. Unfortunately, this cost me more than expected, when I found that the ambient temperatures were too low, and had to invest in a heat tray! But the cider is now bubbling away merrily.

The WOW wine, is somewhat experimental. I have calculated the ingredients (sugar content) of this to drive a sachet of High Alcohol yeast to its limits. This should hit 18% ABV, if not more! It is also based on a tropical juice mix! Ive no ideal how it will turn out, but the must smelt and tasted amazing! I suppose I will know in a few weeks!

Tomorrow is the first performance of my youngest lads school Christmas show. There was something of a panic on Friday that the show would be without stage lighting, when it was discovered the DMX controller wouldnt work! A call went out for anyone with knowledge of stage lighting to contact the school...

...well, its about 20 years since I worked on stage lighting, and ive no experience of DMX, but I offered my services anyway, on the presumption that it would likely be a simple fault.

And indeed it was. The DC input socket had been flexed a bit too much and the PCB track at the positive socket pin has cracked.


Around half an hour in the workshop, and I had linked out all the power input connections to the nearest suitable solid connection. The school had their controller back, fully working, by the end of the school day.

Ive also finally been bothered to reconnect the power supply to my WSPR beacon. This I will leave on 40m for a while.



On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Tuesday, 12 December 2017

LED Emergency Lights - Arranging for 12v supply

Apart from the need to test a number of individual LEDs on each of these Emergency Lamps, which are considerably dimmer than the others (so might need replacing from my LED stock), the big problem with repurposing these lamps is the need to arrange for the 3.9v constant currant LED array to be fed from a 12v source. The on-board 7135 current regulator cannot handle above 6v input, so I need an efficient way to drop 12v at about half an amp, down to between 4-6v for the current regulator.

I had planned on using 7805 linear positive 3-terminal devices, but using these to drop 8v at 500mA will consume 4W and they will get damn hot. Plus theres then the hassle of arranging smoothing and decoupling.

So, at the risk of having to wait for them to arrive from China, ive opted to go for pre-built Buck Converter modules based on the LM2596 device.

At under a sov each, I cant build them for this price! And being adjustable, I can set the output of the module to correspond with a sweet spot in the input range of the 7135 device. These devices, being switching converters, are considerably more efficient than the linear 7805, so should run much cooler.

I could probably arrange to trickle charge the 3.9v 1500mA NiCd packs in each lamp as well.


On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Brrrr Its bloody cold

Having had a sick little monster to look after today, ive not ventured out of the house, other than to check Milly the rabbits water and go to the recycling bins.

I had planned on going for a woodland walk with the camera, plus a little shopping, this morning, followed by an hour or two out with the detector in the afternoon. Instead, my car has now sat for 26h covered in ice, and will remain sat that way until 07:00 tomorrow - at which time, I will attempt to get it started for the quarter mile drive to the garage, where it is booked in to have the starter motor replaced! The failing starter is most unreliable when cold....

Im also mildy annoyed. I have, or rather had,  a couple of items on order from 7dayshop. I was hoping these would arrive tomorrow as they are part of a christmas gift. I discovered today that, without any word, they had cancelled and refunded my order! Apparently the items were out of stock - not according to the website when ordered!

A word to suppliers -
1) make sure your stock control algorithm works and update your webpages!
2) if you have to cancel someones order, at least put a note on saying why!

As it happens, I found a suitable alternative, despite not being offered one, and ended up re-ordering from 7dayshop, since they are still the cheapest, reliable supplier I know. I did also manage to find a voucher code, so got a couple % off, meaning I only had to spend an extra 70p or so.




On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit! 

Monday, 11 December 2017

Free fermentation bucket!

Someone at work brought in the remains of their kids Halloween sweets a while back, which came in a big tub. This was a 5kg Swizzles Party Pack


Once empty, I noticed it had a really good tight fitting lid, and was marked as food safe polypropylene. Hmmm, thinks me - I bet that has around 8 or so litres volume, would make a good fermentation bucket!

So, I 'claimed' it. Filling it one litre at a time with water, and marking it off, it turns out it holds 12L when filled right to the top.

I also noted a small, slightly thicker spot on the lid, perhaps something to do with the molding machine. Using a tapered drill bit, and a spare airlock as a gauge, I drilled a hole here until the airlock 'almost' fit, then proceeded to cut one turn at a time, until the airlock would push in snugly. 


Hey Presto! A 12L fermentation bucket absolutely free! Just in time to put on a gallon of Turbo Cider this week!

On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Tuesday, 5 December 2017

LED Escape Lights - Repurposing

My two boys have, for their play 'crib', a large shed. But this time of year they get little use from it, because its dark.

It just so happens though, that Ive acquired a pair of LED Emergency Escape Lights - the sort of thing you see over fire exits. Now, these are supposed to sit there, connected to the mains, keeping an internal battery charged, until such time as the mains fails, and then they illuminate for 30mins, to provide a guide for anyone attempting to escape a dark and possibly smoke filled building.

The pair Ive obtained each have an array of 27 5mm white LEDs, along with the charging and control circuit board and a 3.9v 1500mAh NiCd battery.


 Immediately, the possibility of converting these into 12v 'penthouse' lamps comes to mind. A 12v system is safe enough that I can let the boys have full control over it - so long as the supply is secure. In this case, the supply will be a large Sealed Lead Acid Battery, so all thats needed is a box.

The LEDs are arranged in parallel groups of three, each group with a 1ohm current limit resistor, on a single long PCB strip. The majority of the main PCB in each lamp is the mains switch mode inverter and battery charger circuit.


Most of the mainboards circuitry is therefore of no use for the new application. The only part that is, is the small black device in the center of the photo below



This is a 7135 Low Drop Out constant current regulator. Its job, is to provide a fixed 350mA drive to the LEDs. This works out at around 13mA per LED at 3v.

There is one problem though - the 7135 has a maximum input voltage of 6v! So, a further regulator, or other voltage dropping technique, is still required to bring the 12v supply down to within the 3-6v range of the 7135. Luckily, the industry standard 7805 1A 5v regulator, is incredibly cheap, and I likely have several in stock.



On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Saturday, 25 November 2017

Control and Programming Software for the ubc125xlt

One of the things ive found playing with my new toy, is that controlling it is not exactly the most intuitive process! It does take a bit of getting to grips with, and the manual, although not Chinglish, is far from straightforward or well laid out.

Direct entry of a frequency, and its storing in memory, is not as simple as my venerable MVT-7100, but then, the Yupiteru doesnt do alpha-tagging to allow naming of stored channels. So the entry of more than a couple of frequencies is rather tedious and tiresome.

Luckily, a chap by the name of Nick Bailey has created a Visual Basic program to program and control the scanner from a PC.


Scan125 is the programs name, and it can be obtained from http://www.nick-bailey.co.uk/scan125/ 

Its takes a little time to find your way around, but its certainly much easier than direct entry! Especially as the entire scan banks can be edited on the PC, handy when first setting up with a lot of channels to enter!

Two things with it though, first, you must follow the instructions to set up the driver for the scanner properly. Its simple but different! Second, a splash screen will annoy you every 10mins if you dont register the software. Registration is easy but he does do it by a rather odd method involving a lot of clicking of mouse buttons.

For many people, especially those who are new to the use of scanning receivers, the big problem they have is finding something to listen to! Here, I would always suggest to start with the VHF Airband, as there are always signals there. Beyond that, many people give up quickly due to not finding anything to listen to, as the patience required seems to be beyond many. To this end, I would advise at first start up to chuck the PMR446 and UK 'Simple' Business radio frequencies in. These are very widely used due to the low licensing costs (free for PMR446 and £75 every half-decade for Simple).

Those coming to the hobby with a view to listening to the emergency services or mobile phones (as per the good old days!) - FORGET IT!!!


On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

New Toys

As my main interest in general utility listening is more geared towards intercept and identification rather than content, I decided I would finally treat myself to a bit of new kit. I looked at the cost of DMR and dPMR capable scanners, but they are still very much out of my range, and besides, SDR is in many ways a more fitting system for such modes.

So I dropped on a Uniden Bearcat UB125XLT handheld scanner, 2nd hand for a good price. The attraction of this device is Uniden's 'Close Call' feature - a strong signal intercept mode.

The above of course is a stock photo (the giveaway is the model number which has clearly been over-typed! I suspect the original photo was of the US market 125AT version!).

One very useful modification that can be made to scanners is to provide a high impedance raw audio tap from the discriminator. This is very easy to do on the 125 as the headphone output connector is stereo but the unit of course mono - giving an available connection. It just requires the removal of the L- and R- balance resistor, and the addition of a 10k resistor and wire between the discriminator and the audio socket. Rather conveniently, all the important signal paths in this receiver have nice big test points!


 All the photos above show the receiver in various states of dismantlement. The photo of interest is the one bottom right, this is the RF board. The big chip to the left of the IF filter (the big cream block on the lower right) is the IF subsystem IC, to the left of this is a large test pad for the discriminator output, marked DISC. At the top of the board between the BNC socket and the volume pot, can be seen the 3.5mm stereo jack socket. Just below that the balance resistor.

Later today I will perform the discriminator mod. But only once my workshop has warmed up!

On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Wednesday, 15 November 2017

Software Defined Radio and Pager Decoding

Ive been playing again recently with my cheap R820T RTL dongles. These, when used with suitable custom drivers and SDR software, are interesting devices allowing for the reception of all manner of signals.

In this case, ive been using mine with the SDRsharp software package to control them (referred to as SDR#), and playing with attempts to receive and decode digital audio and trunked network signals. Ive not had much luck that way yet, but what I have had success with are pager signals.

Some of you reading this (I suspect most of my readers!) will be old enough to remember the period in the mid 1980s to the early 90s when mobile phones were the size of a housebrick, public payphones either vandalised or used as conveniences, and the alternative to a landline the very short lived Rabbit DECT system!

During this telecommunications chaos, those who wished to look like Yuppies but without the budget for a phone, carried a pager. My mate Ian had one - I dont actually recall it ever beeping! ;-) Most people think these legacy devices are obsolete with the coming of GSM phones, but no, they still exist, now used mostly for alerting on-call staff, sending telemetry messages, and are also now a valuable part of the emergency services response systems.

These devices live on the VHF bands around 138MHz and 153MHz. Two protocols are still in general use - POCSAG (Post Office Code Standards Advisory Group) and FLEX, at several baud rates from 512 and 1200 (POCSAG) to 1600 and 3200 (FLEX)

By combining SDR# with a software package called PDW, these signals can be decoded into their numeric or alphanumeric messages.


There are many users of these systems, and it seems different channels carry generally different traffic. The frequency in use in the image above is 153.275MHz. This is a 1200bd POCSAG signal, with timing/test messages (not decodable) every minute. When there is message traffic, it is generally numeric or simple tone alerting. Likewise its apparent sister frequency 153.250MHz. To the right in the waterfall can be seen 153.325MHz (3600bd FLEX) which seems to carry a lot of machinery telemetry and general 'call so and so' messages, and 153.350MHz, 1200bd POCSAG (CH3), which for me is the easiest and generally busiest frequency. To the left of the waterfall can be seen another FLEX channel, 153.025MHz, this also transmits a very regular timing pulse, as can be seen.

For anyone trying the above software combination, I have found that the following settings work for me - RTL gain 38dB (adjust this on yours to get signal peaks around 30dB above the noise), receiver bandwidth 15kHz, SDR# audio out 54dB.

I have spent quite some time exploring the 153MHz channels, so now will move down to 138MHz and try my hand at decoding those.

On a related note, ive taken the plunge today and purchased a Uniden UBC-125xlt handheld scanner. This isnt to replace my venerable Yupiteru MVT-7100, but instead to add to my capabilities with its 'close call' features. Ive also ordered another R820T2 SDR dongle, and a pair of MCX to BNC pigtail cables, as I intend enclosing the dongles into aluminium boxes to help cut down the noise floor.

Tuesday, 7 November 2017

A Plug for Bulb...

My energy supplier (electricity and gas) is Bulb Ltd. They run a referral program for new customers.
The link below ive provided for anyone who is considering switching energy suppliers, to take a look and do your own research into them. Take a look at their reviews online as well.

https://bulb.co.uk/

So, your thinking, all well and good, but how does that help your readers save money?

Well, its simple - If you sign up to change your supplier to them, using a link that I will provide below, they give you a £50 initial credit! And, whats even better - they give me one as well!

Heres the link -

bulb.co.uk/refer/martin7906

Numbers Stations

Many years ago, at the height of the Cold War (mid 1980s - not the mid '60s as the press would have it!) , I used to listen to strange broadcasts consisting of spoken groups of numbers. Much later I discovered these 'numbers' stations, existed all over the world, and were government run covert stations, transmitting operational orders to 'agents in place', what the thriller writers would call spies.

Since the fall of the Berlin Wall, these stations have much decreased in number and activity - but they do still exist!

This morning, I have been listening to one named E11 (these names come from the CONET project, that documented these stations), on 7317kHz USB.

The original Enigma and CONET projects no longer exist, however there is still a group that is documenting these stations -

http://priyom.org/

One great aspect of this projects website, is that on the homepage there is a schedule and a 'next station' timer! This makes tuning these stations in very easy - simply tune to the frequency and mode shown for the 'next station' and wait...