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.


March 15, 2011

Keeping Frequencies Clear On HF and The Latest On The CC-40

The news from Japan continues to unfold on a daily basis. After reading so many reports from official news channels and reactions in so many personal blogs, it’s hard to know what to say without repeating what others have said. It is difficult to imagine what those affected must be going through right now.  I don’t imagine it’s possible to know what it’s like to have to go from having a house and a decent life to spending nights in near freezing weather with little or no water, food or other possessions.  One lady who spoke to a reporter was even having to borrow a pair of socks from a neighbor. Imagine losing everything; I don’t think we can unless we were to go through that experience.

JARL has requested that amateurs worldwide keep a set of frequencies clear in order to aid emergency communications efforts by amateurs in Japan. Other reports have requested that we keep clear a window of ±5KHz around these spot frequencies and this seems reasonable, given that Japanese amateurs will be using SSB.  Most of the time it’s pretty unlikely that CW QRP signals from US amateurs will interfere with these emergency communications from Japanese hams, but given the magnitude of this disaster and the fact that theirs is definitely the greater need, I’m keeping clear of 7025-7035 when on 40M, the band on which I spend most of my time, and I hope that others will do so too.

Listening to 7030, it’s apparent that not everyone is doing this. Perhaps they’re not too well connected with the internet and didn’t hear about the request from JARL or perhaps they assume that at many times of day, the chances of them interfering with communications in Japan are slight to nil. The interference justification is a valid one during the daytime but I’m staying away from that window anyway just to be sure, and as a measure of respect. Who knew I would miss a 10KHZ slice of band so much – I hadn’t really thought about it, but on looking through the log, the majority of my QSO’s are on or near 7030. Sure, I go up and down the band, and also to other bands, but for me, the meat and potatoes of my QRP CW life is hanging around 7030.

In the past when looking at designs of simple rockbound transceivers, I often felt that I was giving up a lot by opting for the simplicity of rock-bound design and would direct my interest toward more frequency agile circuits.  In the past year since going almost completely 100% CW with VFO-controlled rigs, when on 40M, I leave the rig on 7030 and sit there. I might as well have opted for the crystal-controlled designs!

The point that I’m trying to get to is that I often mentally discount simpler designs because I want a radio that will “do it all”, or at least do quite a lot.  There are two ways of doing a lot though.  You can either do it on all frequencies, modes and bands, or you can pick one simple approach (in this case QRP CW on 7030) and stick with it. For others, their one thing is CW on Top Band, or eme using JT-65.

Talking of 40M CW, Jason NT7S has experienced a few unforeseen challenges with the design of the CC-40 which have all been overcome. The most recent difficulty resulted in him implementing a design change that actually improves the rig’s performance; current consumption was creeping up towards 40mA on receive but is now in the region of 25mA with no loss in performance, due to cleverly switching off the micro-controller when not in use.  I find the prospect of a 40M superhet with a 500Hz filter that only consumes 25mA quite exciting – especially as I plan to power my station from solar eventually. The frequency coverage will be somewhere in the region of 40-50KHz, so I plan on setting it up to cover the bottom 45KHz or so of the band.  If you told me that I could only have a 50KHz slice of amateur spectrum, I’d opt for 7000-7050 without even stopping to think about it twice, so the CC-40 could well represent my ideal basic amateur rig.

Keeping my fingers crossed, I should to be able to report within a week or two on this blog that the CC-40 Beta Kit has been received at AA7EE, and at that point hopefully Jason will be able to take a brief and much deserved break (I bet he’s laughing as he reads this.)

March 9, 2011

“Any Old Piece Of Wire Will Do” or “Why It’s Good To Forget What You’ve Learned”

Filed under: Amateur Radio,Ham Radio,QRP — AA7EE @ 8:23 pm
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I miss making blog posts about building kits.  I think the last major one I did was about building the Tut80, and before that, the Norcal 2N2/40.  It’s been a while since those posts, so I’m looking forward to posting about the building and operating of Etherkit’s new CC-40 QRP CW transceiver.  Many of the blogs I follow are updated on a much more regular basis than mine, and I enjoy reading them, so although I don’t think I’ll be able to offer the content that many of my favorite blogs do, I can at least pass along my rambling ham radio thoughts while I wait for the beta kit of the Etherkit CC-40 to arrive at the AA7EE QTH.

The current antenna here is an inverted vee cut for 40M. The center is supported by a 32 foot fiberglass windsock mast that I bought from The Mast Company.  It’s mounted on the balcony of my house, which is about 15 feet above ground, putting the center of the dipole at about 47 feet.  75 feet of  JSC Mini RG-8/U type 3060 connects the dipole to my Z11 tuner, which is sitting right next to the FT-817. It’s cut for 40, so works great there. It also works on 15 – not sure how well as I haven’t had many QSO’s on 15 yet.

So far so good – a 40M dipole is expected to work on both 40 and 15, so no surprises there. Lately though, with the sunspots becoming postively more sociable, I’ve been wanting to be QRV on other HF bands too. At some point soon I will most likely try feeding a dipole with balanced line for all HF band coverage but right now I don’t want to mess with the coax-fed 40M dipole as it’s working great on 40, and I want it to remain that way for giving the CC-40 it’s on-air testing.

So what to do? I know that I can use the Z11 tuner (which is located next to the rig) to present an acceptable impedance to the rig so that it will transmit on any HF band, but I also know that on bands other than 40 and 15, the mismatch at the center of the dipole will be great, incurring losses in the coax. In other words, only a bozo who doesn’t know his antenna theory would try to load up a coax-fed 40M dipole on bands other than 40 and 15 with an antenna tuner located at the rig.

So I tried it.

And it gets out.

Amongst the QSO’s I’ve had with this “unwise and inadvisable” antenna (my quote marks) are FG5FR on 30M and LU4FLJ on 12M.  On 30M this morning, I QSO’ed with AB7KT who was running the same power as me – 5 watts (not sure what his antenna was). He gave me a 579 and I gave him a 559.  Also on 30M, WB7NZI was running 83W (odd figure) to a dipole.  He gave me a 559 and I gave him a 589. KD0V was running 100W to a 3 ele beam at 50 feet.  He gave me a 579 and I gave him a 589.  Remember that there is 5W coming out of my transmitter (not sure what the erp is).  There are many other examples, but I have had successful QSO’s on 40, 30, 20, 15 and 12  – all on an antenna system that my understanding of antennas dictates should only work well on 40 and 15.

Does anyone reading this know how I could model or otherwise calculate the theoretical losses for such an antenna on bands other than 40 and 15? I’d love to know what the theoretical losses are on this system on bands other than the one for which it was designed, because going on just signal reports alone, the losses don’t seem to be that great. Although I haven’t had QSO’s on 80 or 10 with it, I have seen my spots on the Reverse Beacon Network, and the SNR figures are quite encouraging.

March 6, 2011

Signalink USB Fried

I live in an old house with equally old wiring.  There is no ground anywhere in the house – all the electrical outlets have just 2 connections. I’ve thought for a while that I should drive a long copper rod into the earth outside for my station ground, and if I had done this, then the following might not have happened.

A week or two ago I noticed that when I touched the metal casing of either my FT-817 or Z11 tuner, I felt a sharp tingling of electricity – the metal cases were no longer at ground potential. If I remember correctly, we had experienced some storms recently, so perhaps there was static buildup on the cases. Shortly afterward, I noticed that the Signalink USB was cycling the FT-817 transmit mode on and off continuously. Turning the delay pot on the Signalink USB fully counterclockwise kept the PTT switched on permanently. On opening it up, I noticed the the chip at the top right-hand side of the board in the following picture (just above the crystal) was very hot:

This was not good.  On calling Tigertronics technical support, they confirmed that the symptoms sounded very much like the unit had suffered damage from static. If I shipped it back to them, they would take out the old board and install a new one with the same case and knobs for $49.95 plus the cost of shipping it back to me.  This sounded reasonable – even if they had opted to fix my board at the component level, the cost of labor would bring the final cost  to the same point (or even more).

The helpful tech gave me an RMA and I was all set to return my Signalink USB for a replacement board when it occurred to me that I haven’t actually used it in a couple of months. The most use I have made of it was when I was doing WSPR last year and the year before. Other than that, it has been useful on the occasion that I decide to fiddle around with a digital mode for fun, which I have done on occasion, but none of the digital modes have held my attention.

The only digital mode I’ve consistently used recently, in fact the only mode I’ve used recently, is CW, and I don’t use a computer to decode it – I use my head. For this reason, I think I’m going to hold back on getting the board in the Signalink USB replaced.  It’s a fair deal, but there are other things I can do with my ham radio dollars right now.

In other news, Jason NT7S hopes to ship the beta kits for the CC-40 transceiver to the beta testers this coming week.  If all goes well, you’ll see pictures and a description of the beta version of the kit on this blog in perhaps 2 – 2 1/2 weeks. I’m furiously trying to improve my sending on the paddle and wondering if my continuous mis-keying is due to operator error, or the fact that my Bencher paddle feels a little springy when set to operate from a light touch. It could well be a case of a bad workman blaming his tools, but I’m wondering what other types of paddle feel like.  I don’t think the Bencher is my ideal paddle and am wondering which other ones to try. What about a single lever paddle – does anyone have thoughts on that? I quite like the idea of the single lever paddle.

I was unable to operate the ARRL CW DX Contest due to an out of town trip. What awful timing!  I’m available almost every weekend except that particular one.  I was home this weekend for the ARRL Phone DX Contest but couldn’t make myself pick up a mic.  I did finally call a couple of stations in the contest, but was privately relieved when they didn’t come back to me, as I really didn’t want to muddy up the log with any phone contacts. Since taking up CW, phone has lost it’s appeal.  I really enjoy the mental exercise of decoding CW, and phone operation just doesn’t offer the same engagement; it seems too easy. That’s my take – I’m sure phone operators will have a different perspective.  I’d be happy to hear from you guys here.

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