Mag Loop – Part 2

Well got the 28mm pipe from Plumbase Ely (01354 663711), excellent service and very reasonable delivery charge, spent £2.99 at Argos for children’s play sand, filled the pipe and sealed the ends with insulating tape.

The Bending Rig (link) worked ok, the grooves were designed for 37mm pipe so the 28mm flared slightly due to the high walls, also as the spacing of the rollers was quite wide, the bend started at a fixed point set back from the end of the pipe which means the circle can’t be fully formed this might make connecting difficult if I decide on a dual loop configuration.

The pipe has a number of compression creases which is a shame, the crease at the bottom of the bend was due to me thinking that I could close the last few inches by pulling the loop together – WRONG!!, but as this was the very first one I’ve ever done, it turned out ok, I do have a spare length of 28mm, so next time I will try not to rush the bending process and I might even try and heat and anneal the pipe so as to make even more malleable.

SAM_5300 (Medium) Loop held by my very able other half.

Mag Loop Bender Rig

Made the pipe bender for the magnetic loop today, the idea is that by slowly bringing the pinch roller closer to the static rollers after each pass of the copper pipe, a bend will be introduced, repeating this with slightly more pressure will ultimately form a loop.

I thought how best to engineer the screw mechanism to apply pressure to the pinch roller against the static rollers and decided it was time to dust off my old trusty Workmate bench.

SAM_5296 (Medium)

The wood grooved rollers were made locally after I put a shout out on ‘Streetlife’ a local community website, these were made to accommodate 37mm pipe as that will be the maximum I will ever be able to afford!

In order to make the rollers, freely rotate I fitted bearings with a 10mm shaft size (10off 25mm x 8mm shielded bearings for £5.12 Ebay).

SAM_5292 (Medium)

I drilled three 10mm holes through the Workmate top (I did look at using the existing holes on the Workmate top and sleeving them, but their was no benefit over drilling relatively small holes), using 10mm threaded rod I passed this through the worktop (2off 10mm x 500mm £3.00 Wicks).

SAM_5293 (Medium)

Made up a cheap and cheerful handle (Flat bar 1m x 25mm x 5mm £7.12 Wicks) for the pinch roller and bolted this through the worktop using 10mm threaded rod.

SAM_5294 (Medium)

SAM_5295 (Medium)

The next step is to get some lengths of 28mm copper pipe and see if it works, I’ll be using sand inside the pipe in the hope of avoiding any creasing,(fingers crossed).

Link to my first result of bending 28mm pipe.

Replacement Anti-Virus Installed

I originally used Norton Anti-Virus across 5 PC’s in the house but the annual renewal costs were getting a bit silly, especially as I want to buy radio stuff so savings have to be made!

The family bank with Barclays and they offer each account holder FREE Kaspersky Anti-Virus software with two PC licences, I have downloaded the program and linked the accounts to a centralized web based dashboard and everything is working just fine, as I have three PCs including the weather PC, it costs an additional £9.95 for 5 PC licensing which is a great offer in my view, (I did try the free AVG Anti-Virus program but was plagued with ‘buy now’ and ‘upgrade’ messages).

Kaspersky Total Security is free if you bank with Barclays, the link is at the bottom of your online banking page.

Added Daily Records Page

Added a new Daily Records page to Chatteris Weather, this compares previous daily records to current, this information is all on one page per month, it is quite interesting to see what the readings were then and now.

A drop down month selector is at the top of the web page with records going back to December 2013, the page can be accessed via the Daily Records link above or from the Chatteris home page, ‘Almanac’ on the menubar and select ‘Daily Records’.

Mag Loop Vacuum Capacitor

The mag loop build project is getting nearer, I have the MFJ antenna analyzer, the control method is being worked through and the grooved rollers have been made so I can bend the copper pipe into a loop, the most expensive item required for the loop to work effectively is the tuning capacitor.

SAM_5285 (Medium)

Details:-
Russian (Soviet) Vacuum Variable Capacitor KP1-12, 10-1200 pF, 4 kV, 50 A, 30 MHz.
Main technical data:
Min. capacity – 10 pF (+/- 10%).
Max. capacity – 1200 pF (+/- 5%).
Nominal operating voltage – 4 kV.
Nominal HF current – 50A.
Frequency range – up to 30 MHz.
Glass body temperature range – up to 140 o F.
Height – 7.87 in. (~200 mm)
Diameter – 3.54 in (~90 mm).
Weight – 3.31 lb. (~1.6 kg.)

The build quality is excellent, with the turning action being very smooth and returning to the home position easily once holding torque has been removed, I haven’t yet tested that the tube is still under vacuum, I will do this further down the project, the method involves putting the capacitor in the fridge for a while, when the capacitor is removed, if condensation is observed within the glass envelope, you know the tube seal has failed, the other more obvious sign is that the copper plates will oxidize and lose the bright and shiny appearance.

This was bought from Ebay at a cost of £103.20 (vendor to my best price offer saving £26) after a lot of research as I wanted the capacitor to have the widest range so as not to limit me too much on the loop sizes and hence the frequencies of interest I may wish to make in the future, station power output was a consideration which influences the Kv operating voltage rating of the capacitor, however, I will tailor the output power to keep below the operating voltage when needed especially as I do not want to buy another one!
The postage was £36.62 which I thought was a bit expensive, however, I have never seen such comprehensive packaging to protect an item and this all adds to the weight, so overall, I’m happy and feel I have value for money.

Arduino Uno

As a licensed listener 🙂 one of the aspects which drew me to radio as a hobby was the huge variety of paths it can take you down, I would like to construct a Mag Loop antenna, Peter M0DCV gave a really interesting and informative talk and demonstration at a club evening, not only was their the construction element which attracted me, but how the loop was controlled and tuned.

Looking on the internet and YouTube shows plenty of mag loops being controlled via an Arduino, this is completely new to me so the best place for me to start was to get a starter kit off Ebay, the kit cost £31 and is an Arduino clone (Sintron) and contains everything to play with, (Servos, leds, LCD displays etc) well everything apart from an instruction book, fortunately after the purchase, the vendor sends you a link to download a whole host of manuals and projects.

I was up and running within about 10 minutes with the first project which was to make the on board led flash, the next project was the make traffic lights following the UK convention and this setup is in the picture, this slowly slowly approach is good for me as I’m learning how the code works and what are the effects when you make changes.

The ultimate aim is to download a program which will control a motor connected to the tuning control on a mag loop.

SAM_5281 (Medium)

Note – The ribbon patch connectors in the picture was bought separately, again from Ebay for £0.99p including free postage!

I have ordered a larger motor, motor interface and rotary enumerator, once configured, the motor will mimic the turns of the manual rotary control. I will post up more when it arrives.

MFJ 269C Pro Analyser

I realised fairly early on that I would need some form of antenna analyser if I was to build my own, the decision was then which one and how much to spend!

mfj269c

I opted to buy the MFJ260C Pro – Link to Manual as this has all the frequency ranges that I will need and a number of very useful, added value features, such as:
Coax Loss measurement
Cable Length
Length (distance) to open or short circuit
Capacitance in pico Farads
Inductance in micro Henries
Frequency Counter

The money to help pay for this came from not having to pay two months of council taxes, I ordered the unit from Ham Radio Outlet, New Hampshire, USA, their was a January promotion of a $50 reduction which eased the pain a bit!

The meter took 4 days to reach the Parcel Force Cambridge depot where it sat until I paid £64 release fee (£54 VAT and £8 handing fee), it would have been nice if I didn’t have to pay this, but I knew when I ordered it that it was a real possibility, nevertheless, I saved over £71.00!

Well I didn’t actually save £71 as the unit needs batteries to be portable, I bought rechargeable ones as I didn’t want to keep opening the case to remove batteries when not in use, also this allows me to regularly keep the batteries charged in-situ, the downside was that these cost nearly £30 – (10 AA 2000mAH batteries bought in packs of 4 from Argos).

I’ll give another write-up once I know how to turn it on 🙂

General information and status updates.