Andy's Tips

 In no particular order !

Tuning an ATU for best efficiency. Simple - use minimum inductance and whatever capacitance is required to achieve an impedance match. This way always obtains the highest Q = max efficiency. In essence, use a Nano VNA or similar and check that you have a deep and narrow S11 or SWR vs BANDWIDTH curve. The deeper and the narrowest represents highest effiency. An SWR etc over a large bandwidth indicates bad losses, don't get caught out !

50Mhz propagation. I've been using the 6m band since about 1987 when we first got a general release in the UK. It's an odd band. When it's open it really works well for QRP and there's a lot of CW too. I've also in recent years observed how openings work on the band using QRSS backed up with my experience from the early days. There seems to be one clear rule. Point to point propagation paths only tend to last about 10 minutes. Please understand point to point! That's totally different from the band being open generally, where it can be a random, but many other point to point openings between stations. Keep your QSO length very short and then move on. And remember the old days of TVDX ? Five or ten minutes of pictures from wherever and then it was gone, confirming the same effect. 

The Twente SDR receiver. A great online SDR with no time limits based in Holland. And it's easy to embed a frequency within the URL for sending links , for example http://websdr.ewi.utwente.nl:8901/?tune=10000am

Electrostatic prevention. Things like Nano VNA's and Spectrum analysers are VERY sensitive to electrostatic discharge. Your antenna could easily be charged with 10,000 volts of static (seriously) and you'd never know. So before connecting it, touch the outer and the inner to a nearby ground to discharge it just in case. Also if you wear what I call "safety boots", you could be charged up too. Discharge yourself in the same manner just in case you end up sending lots of volts up the input.

Browser tips. Use F11 for full screen view to have a much nicer view of a website. Also if you are having trouble viewing some graphics, put the mouse over the picture, right click the mouse and SAVE AS option will save you a nice full fat graphic to view in your favourite viewer.

Ripping a website. Use wget -mpEk https://sites.google.com/view/andy-g0ftd/home Remember that no website lasts forever, grab and save for personal use. Note  - this does not download external links or Google drive files. This is a level on downloader.

Good antenna poles (fishing poles) -  Verified as good, fibreglass, not carbon fibre.  Made by Lineaeffe. Labelled as Called a Lineaffe International Pro Series. The sticker also reads:Super High Fiber Glass Twin Action. And some strange labelling that I don't quite understand. Just says 20-40 NEXT 7007 FGA. Closed length 115cm, 685 grammes. Cost about £25 for  a 7m long pole. They are of the telescopic type, not swaged or "take apart" that can lead to confusion and section sticking errors.

Saving webpages easily. In the old days we used to save webpages that usually included two folders. One with the graphics files and another with the basic textual HTML stuff.  These days you can save the whole page easily to one pdf file by using your browser's save or print to pdf file instead. It makes saving or printing much easier.

Ever tried writing data or something like an image to an SD Card for a Raspberry and had unexplained failures ? So you think you've formatted, usually max 32Gb for a primary partition for Pi3B''s and below. You've cleared the partition data and recreated it and the thing still fails ?  Well I've discovered you're bog standard Android phone seems to know how to do things better (a rarity since it's a such a crappy OS). Throw the iffy SD card in your phone and it will detect the errors and correct them quite nicely. Yep, oddly enough this has been the most consistent method of fixing micro sd cards.

Icom rig support. Icom USA (so I guess that means global outlets too) announced that many Icom rigs are no longer going to be supported due to spare parts issues.  Original announcement here. [Now a dead link August 2024) Or a copy here. [Just as well I saved it].

Using diodes as voltage droppers. Diodes tend to achieve the circa 0.6v drop when they are being run near their max current rating. Shove a 10 amp diode in line when drawing 500ma will usually only drop about 0.3v etc. Or just include a few more diodes than necessary in the circuit to get the right voltage.

Making ATU's and tuned circuits. Best Q is achieved by assuming 1.33pf for every metre of wavelength and then building a coil to achieve the desired resonance, assuming a system impedance of 50 ohms,

Short antennas and losses. By the time you get down to about a 1/8 wave radiator in theory you only lose about 1db. Typical radiation resistance is about 5-10 Ohms. But now you have to consider matching circuit losses especially with the inductance used. This starts to become an appreciable part of the overall circuit, and then the power lost in the inductance can start to take over. Whence why we try to use high Q low resistance coils. A good coil might add 6db loss.  A bad one, or one that is added to an even smaller antenna ends up with an antenna maybe only radiating 1-2% of it's power input ! Thi s is a BASIC explanation to get you readers started.

Powering old cellphones from 5v USB only. Don't throw away the old battery ! In some phones I discovered that if you totally remove the battery pack then the 5v DC USB supply is stopped from powering the device. You need to keep that old battery in the phone.

Crackle paint finish. Many radio builders like to paint their boxes with old style "crackle paint". It's usually available from auto spares outlets. It's great stuff but don't believe the instructions when it says that no primer is needed. That's a load of rubbish. ALWAYS use a primer / undercoat or it will not work!

A good glue. Ever wanted to give panel sockets a bit more stability from working loose and twisting ? Stick heat sinks onto components ? Fix toroids to PCB's ?  Glue tiles to bathroom walls ? Use a PVA type wood glue. Brilliant stuff. Unlike superglues or Araldite, PVA type wood glue dries CLEAR and without bubbles. And it remains workable for a while, and the excess can be cleaned off easily. It comes out the tube white but dries like clear latex. And it's VERY strong. I use wood glue from the "151" brand. A very large tube cost only a quid, from a Pound shop of course.

A good glue (2). E7000 and T7000 are black or white coloured adhesives of medium strength. They tend to be used for what I call sealing the "crackback" cellphones. Crack backs are where you are required to crack the rear panel off the phone in order to insert a SIM card or SD card. However that leaves the rear panel a bit vulnerable if you do not use a jelly style "condom" as an every day protector against scratches or knocks. That's where this glue come in. Priced a good seal, medioum strength and comes in a tube with an almost syringe style applicator for ensuring accurate deployments and minimal wastage. Perfect for stuff like sticking ferrite toroids together, or small items where so called super glues leave an ugly residue behind. Expect to pay about £5 for a 50g tube delivered on Ebay.

Tell tale signs of hard disk failure.  After some 30 years of observations I found that apart from the usual "click of death",  that slow shutdowns, slow start ups and increased crashes are definately signs that something is up to no good. Scandisk or FSCK is a waste of time in marking bad sectors.  SMART stats are stats, and don't seem to mark bad sectors properly. Reinstalling an operating system appears to work in the short term but rarely works long term. It's not worth the hassle of messing about with software solutions. Just buy a new drive and have done with it. Amazingly, the only drive that failed on me was only a few days over it's warranty period and when I took it apart I could see nothing wrong with it's platter. No scoring or dust. But I also suspect that I had also used the drive in a hotter than usual environment and it roughly coincides with the problems starting to appear.

Got a Wouxun handheld rig ? Nice rigs, but they do tend to have a rather high leakage current when switched off through the electronic on/off switch. (There's no hard on / off as I call it). The result is that if you store these handhelds for a month or two then the battery is depleted. And depleted batteries that don't get charge get knackered ! The solution is to insert a bit of paper to separate the  battery terminals from the input terminals on the back of the rig, and then give it a top up charge maybe every 4 weeks or so.  And anyone, one day it will die of natural death, so invest in an AA cell case and some Eneloop AA's for future proofing the rigs.

Power supply smoothing capacitor values. Rule of thumb (assumes using full wave rectification) is that you need about 1.0 - 1.5uF per milliamp of power drawn. E.g. 1000uF per amp being drawn.  These values should be good enough for both 50/60Hz systems. Too low results in insufficient smoothing. Too high results in large inrush currents that may damage transformer windings or other components. 

Got a slightly low regulator output ? Check that it's not accidentally oscillating somewhere. You may observe some weird crap at a few Mhz or 5Mhz area if there is bad decoupling somewhere etc.

Voltage regulators don't provide reverse polarity protection. A lot of folks forget that these device only regulate and they don't provide reverse polarity protection. In fact, shove 12v the wrong way up a 5v regulator and see 9v   output. Not good if you're trying to preserve sensitive equipment like microprocessors or kits that have not bothered to provide protection.  Make sure you insert a series diode before the input of regulator.

Making LC circuits. When making any LC circuit, from an ATU to a simple receiver then the rule of thumb is to use 1.3pF per metre of wavelength, and then wind a coil to suit and eventually bring to resonance. This rule of thumb preserves a typical working Q of 10 as well as presenting sensible values of components.

Lithium Ion batteries in AA format. They are called LC-14500 size. Useful for making small QRP rig batteries when physical size matters, and can be put into a standard AA cell case. My own interest in them came about through VHF/UHF handhelds. Some older handhelds where it's impossible to obtain or repack and old battery pack often came with cells case, BUT, some of these cell cases only allowed maybe 3 x AA's in them. Reduced voltage = reduced RF output. A 5w handled typically becomes maybe a 2w output, or less. And besides, AA cells with constant current being drawn are utterly hopeless. (They have current capacity, but drawing even a measly 200ma soon dips the voltage badly). Enter the LC-14500, stuff those in place, volts are back up and current can be drawn without the terminal voltage going down the pan in 60 seconds.

Eneloop Ni-Mh cells. Throw away you old style Ni-Mh cells because they are redundant. Eneloop cells are brilliant. For once something real has come along that improves upon rechargable cells. They keep their charge for up to 10 years, like an alkaline style battery, great for keeping on standby. Normal Ni-Mh's lose charge after about one month. Like ALL other cells, they MUST Be kept in a charged state, or charged shortly after discharge otherwise they never recover full capacity - fact ! Same goes for just about any other rechargable cell, including lead acid car batteries, Nicads etc. Note - these cells appear to retain a high terminal voltage circa 1.5v but very quickly settle to about 1.3 volts after a VERY short space of time, usually about 10 mins after load. This could confuse anyone who watches battery indicators with fervour ! It's nothing to  worry about. Some equipment has a menu option to switch the characteristics of the battery monitor function. If in doubt, use the NiCad or NiMh option and NOT the alkaline option. Eneloops are still Ni-Mh technology, but with a much lower self discharge chemistry. I recently did a test of some 1900mA AA cells after 6 months. They only lost 55ma per month.

Drilling through foam. What you say ? Well sometimes if you want to make holes in foam, maybe as spacers for projects, as I have sometimes needed to, then you'll know how difficult it is to make a neat hole.  Try using a cone cutter or step drill by hand to make the hole. Not perfect but still much neater than other methods.

Gel or sealed lead acid battery's. Over the years I've gained some experience with these. Firstly the useful lifetime of these battery's is at best five years. That's what the typical manufacturers data says. I usually find that it's more like four years regardless of use, but assumes no abuse. Keep them on a trickle charge, never store them un-charged. They WILL fail within a few months ! Limit the initial charge current to no more than about 20% of capacity. High initial charge current will destroy them. Tell tale signs of failure are a warm battery when on trickle charge, and an offload terminal voltage that is lower than the charge voltage. Example, if charging at 14 volts then when you initially take of the charger, you should see a healthy 13.5-14 volts. If it's more like 12.5 volts then throw it away, don't waste time with it all !

Lithium Ion charging. Plenty of bad info on the internet. Chargers don't need to be special. Li-Ion's are charged typically at 0.5 - 1.0 of capacity according to manufacturers data. A 1000ma cell should have a maximum charging current of 1 amp and a minimum of 500ma. The critical bit is the terminal voltage. NEVER more than 4.3000000 volts ! 4.20 - 4.25v is best. Never allow the cell to reduce to 2.5v - 3.0v. Higher is better, but you have to choose between usability of the device that they are fitted into, and long term cell longevity. NEVER short circuit or puncture them. Major fire hazard. Useful links https://web.archive.org/web/20210506193027/https://batteryuniversity.com/index.php/learn/article/charging_lithium_ion_batteries and https://batteryuniversity.com/articles

Battery life in years. 5 Years max regardless of how you treat them, store them or use them.  (Lots of experience with Li-Ion's and gel cell type). That's pretty much what manufacturers data sheets say too. Good info for you walkie talky users. That's why when purchasing a handheld radio that I check that they offer a proper empty cell case or at least a 12v dc input socket.

Storing of all batteries types.  One rule - never ever ever ever ever store them uncharged or partially charged. It's guaranteed to ruin them. Also remember that it's no good at all to simple charge a battery and then assume that you can put them away for months or years and they will still be charged BECAUSE THEY WILL NOT BE ! All batteries have a self discharge rate. You must still give them a top up charge perhaps after one month. Exceptions are the Eneloops and to a certain degree Li-Ion types. That latter can still be good after 6 months depending upon exact quality and chemistry. 

ISP filtering. The world is full of some batshit rules. I came across this  little problem recently. I changed ISP and soon after that I discovered that I was unable to download QRSS grabs from Dropbox sites, or reach archive.org amongst some others. Turns our that they get caught up in the .xxx ISP filters and you need to get it turned off. I am grateful to the works of John Jonik - http://wafreepress.org/cartoons/jonik-archive.php   who expresses the situation quite nicely. Here's the modified UK based version. Updated for  the Rishi Sunak regime .