Dave Richards AA7EE

March 19, 2011

Saved By Powerpoles

My mind is an odd mixture of curiousity and completely disinterest. For a long time now I’ve been aware of Anderson Powerpoles. I knew that they were DC power connectors and that they were part of a system that many hams who use them just love. More than that I didn’t know. Sometimes, just the fact that large numbers of people love something arouses the contrarian spirit in me and encourages me to look the other way.  It’s not a good quality.

When I visited HRO in Oakland a few days ago and bought my first ever pack of Powerpole connectors I wasn’t planning on blogging about it, but conversations with other hams in HRO and on Twitter proved to me that a) hams who use Powerpoles love them and like to talk about them and b) there are hams who still don’t use them and are keen to know about them. I thought I was the last ham on the planet to buy into the Powerpole system but it seems that I’m not, hence this post.

For years I’ve been operating my QRP rigs from battery power with a charger attached. I quite like the fact that if the power goes out, the radio just keeps on running and I can continue to operate.  At first, it was a big old lead-acid battery with a motorcycle battery charger permanently attached.  It put 1A into the 100AH battery,  keeping it topped up. Then came the sealed lead acid batteries – a couple of 12V 5AH ones from Radio Shack, and also a couple of 12V 12AH ones that came out of a portable photographic strobe system made by German company Hensel.  When I sold the strobe (to an Aussie photographer who was on vacation in the US and looking to pick up a decent portable flash system) I installed new batteries and snagged the old ones for the shack.

I have a charger made by ELK – the ELK-P624. It’s primarily intended for use in alarm and CCTV systems – that kind of thing. Connecting it up to one battery and one radio (my FT-817) wasn’t hard.  When I started wanting to connect extra batteries and radios, things started to get a bit confusing.  I was using a combination of RCA phono and Radio Shack crimp-on snap connectors.  It wasn’t exactly a mess, but every time I wanted to add one more component to the system I had to stop and think carefully how I was going to configure the connectors. When thinking about the male/female thing, I had to also keep in mind the ease with which a loose male connector could touch another contact, possibly shorting out the battery – these concerns dictated which end of a particular joint was male and which one female. It doesn’t take too many extra components added to such a system before the tangle of wiring turns into a mess.

One of the useful things about Powerpoles is that they have no gender – any Powerpole connector will mate with any other Powerpole connector. This may not strike you as a particularly useful quality unless you’ve had previously tricky wiring problems (like I did) and then experience how much easier Powerpoles make things.  You can ensure protection against reverse polarity by sliding the 2 connector housings together. 2 connectors once mated together, will not be able to make a reverse polarity connection with a similarly attached pair of connectors.  Also, the metal terminals (silver plated for good conductivity) are recessed in their housings, so the chances of accidental shorts are greatly lessened. This page should make things a bit clearer.

It’s not much to look at, but here’s the setup that powers AA7EE. I took this picture out on my balcony, as the batteries are normally located in a dark corner of the shack (not good for photos):

The batteries are 12V 12AH sealed lead-acids. The charger is on top of the right-hand battery.  It’s fixed to the top by a couple of pairs of velcro pads.  See that distribution block between the two batteries? It’s one of the many different types of distribution blocks utilizing Powerpole connectors that are available from different manufacturers. This particular one is a PS-8 distributed by Powerwerx. It’s great – I can plug in extra batteries which will be placed in parallel with all the others,  so I can add to the capacity of the system as I wish.  I can also unplug the charger and plug in a solar panel and controller when I’m ready.  Powerpole connectors make it very easy for me to remove and add components to the system as I wish. Before anyone mentions it – yes I know I should really fuse the battery leads.  I should have taken care of that already.

The fused lead exiting the picture at the bottom is the power cord for my FT-817.  As the FT-817 doesn’t have it’s own reverse voltage protection, I added a diode, which is under the black shrink-wrap just before the cable leaves the frame. For anyone who wants to add reverse voltage protection to a rig, this is how you do it:

If reverse voltage is applied, the diode conducts and the fuse blows. Simple yet effective.

Here’s a close-up of those batteries and that distribution block.  I’m so jazzed that I can plug and unplug parts of this system at will:

The clear and slightly twisted leads leaving the charger go to the wall-transformer that supplies 16.5V AC to the charger. I wonder if I could remove the wall-transformer and connect a solar panel to that pair of leads to use the charger as a solar charge controller? I don’t see why not.

In other news, I finally solved another connection problem – that of easily switching from external speaker (when I am wandering around the shack and monitoring) to headphones (when I am working someone). A simple box with 3 x 3.5mm jack sockets and a DPDT toggle switch and now I don’t have to fumble around for the headphone lead, unplug the speaker and plug in the headphones every time I answer a CQ.  For the sake of overkill, here are 3 pictures of the project (I’m getting in practice for the CC-40):

Here’s the business end of things. Complex control panel. Perhaps we should go to a menu system?

And the wiring inside. I used RG174U but it’s not important. Shields were grounded at one end only. I always used to scrape the surface of Altoids tins before soldering them, having no idea that it was unnecessary. At least I finally found out.  I have a habit of scraping component ends before soldering them. In the 1970’s when I started building circuits, it was often important to do this, as component leads were often untinned and covered in dirt and oxidation. I just started scraping away at almost everything before soldering it.  It’s a hard habit to break:

Such a simple little project, but it makes operating easier and more enjoyable. 4 small adhesive rubber feet stuck on the bottom of the tin complete the headphone switch.  I’m considering making another one exactly the same for switching between straight key and paddle, but since I began using a paddle, haven’t used the key.

That’s all that’s going on here radio-wise, as well as a few QRP QSO’s a day.  I’ve never been one for awards, but it just occurred to me that it wouldn’t be that hard to get QRP WAS, especially with band conditions on the mend.  For most of the time I’ve owned this FT-817 (about 10 years) I’ve worked almost exclusively SSB on HF.  The number of stations who come back to me with 5W of CW as opposed to the 5W of SSB that I used to use is remarkable. The difference is like night and day.  I mention this in case there is anyone reading this who is a new ham or who hasn’t tried CW much before. If you’re new to ham radio and considering a QRP radio, definitely do it if you’re planning on using CW or other digital modes. If the main mode you want to use is SSB, then get yourself a 100W or higher rig. Running 5 or 10W of SSB on the HF bands can prove very discouraging to a newcomer, unless the sunspots are high and you’re on one of the higher bands.

My advice – try CW over SSB. You’ll get a real  feeling of accomplishment from learning and using code on the air. You’ll be able to make a lot of contacts with low power, and if you think 500W of SSB can pack a punch, just think of what a powerhouse of a signal you’ll be if you run 500W of CW!

QRP CW works. John Shannon K3WWP knows this. He has had a minimum of one QRP CW QSO a day for more than 16 years now.

PS – Interesting Powerpole fact – they were developed in the 1960’s for use on the San Francisco Bay Area’s BART train (Bay Area Rapid Transit) system, where they are still in use today.


January 6, 2011

The AA0ZZ Keyer From 4SQRP

As much as I tweet about my fondness for building things in Altoids (or Altoids-type) tins,  I have just 3 projects in these useful and affordable enclosures;

a Softrock 40:

an antenna switch:

and a morse code practice buzzer:

When Altoids first became popular, I saved my tins and ended up with around 15-20 of them, figuring that one day they’d be useful.  Then during a move, I decided to get rid of them and now of  course, wish I hadn’t.  I like the older tins because the top lids are not embossed as the current ones are – better for sticking labels on, if I ever want to do that.

Enter the latest Altoids tin project – the AA0ZZ Keyer, a kit from the 4 States QRP Group, and a Christmas gift from my friend Antoinette:

I haven’t put any labelling on this keyer, as is suggested in the instructions.  They even provide you with artwork in pdf form in many different color schemes, to match the different Altoids tins. Perhaps I’ll get around to it, but I quite the look of leaving the tins as they are.  Construction is straight forward – there are very few parts:

I did have one small challenge, and that was in mounting the 3 small pushbuttons. The manual advises the use of superglue in gel form.  Regular superglue is too runny, and can easily wick up into the actual switch mechanism, gluing it shut. I bought some superglue brand-named “Caliber” that claimed to be a gel.  On squeezing out a little onto the first pushbutton, it proved not to have the consistency of a gel, ran into the switch mechanism and glued it firm. It was at this point I wished that an extra pushbutton had been included for mishaps like this. Luckily, 4SQRP will send you 3 extra pushbuttons for $4 inc shipping.  I put the order through and set about gluing the other 2 pushbuttons, using what had been in my mind to use all along – epoxy. I like using epoxy because you have plenty of time to move things around if they are not right the first time, and when it does set, it sets rock solid.  I don’t mind that you have to wait a few hours for it to set – waiting takes no effort 🙂

The 3 extra pushbuttons arrived in a few days.  I sent the order on Friday afternoon and they arrived the folllowing Wednesday. Here’s a close-up of the pushbuttons fixed firmly in place with epoxy.  It doesn’t look too pretty,  but it’s very functional:

And a complete inside view of the keyer:

So far I’m pretty happy with it, but I have noticed two things.  Firstly, it is not possible to change the ratio of character speed to spacing when sending from the memories.  I like to send characters at a slightly higher speed than the spacing between them.  I learnt the code this way – by learning characters sent at 20 wpm with bigger spaces between them. Then when I wanted to increase my speed I simply closed the gaps between the characters. I like sending this way as it encourages the listener to think of each letter as a particular sound rather than a series of dits and dahs. Ideally I would like to program the memories in this keyer to send with a character speed of 15-18 wpm and a spacing of about 12 wpm.

The other thing, which I’m going to have to find an answer to so that I can use the keyer in the way I’ve been wanting to, and that is that I can’t get the straight key mode to work.  I want to be able to send CQ’s from the keyer memory  (on 7030 most of the time) and then break in with a straight key to answer  calls.  I don’t think I’m doing anything wrong.  The manual says that in straight key mode, either the dit or the dah paddle can be used.  I’m pretty sure I have the dit and dah paddles wired up correctly, as the paddle works fine with the keyer in iambic mode.  All the other commands on the keyer work except the straight key mode.  I wonder if there’s a problem with the PIC programming?

I just joined the 4SQRP e-mail reflector and plan to ask the folks there to see if they can help me out. Otherwise, this is a fun little kit (and it only costs $17 at the time of writing).

Order yours here.

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