When looking at running a random wire of any length the question of if to use a balun or not always comes up. Since they appeared in the early 90’s people have raved that feeding a random wire with a balun and coax is much better than bringing the feed line into the house where the QRM is much higher. Remembering back in the 90’s when there was not that many noisy plasma TVs or switched mode laptop PSUs or even the dreaded PLT using a random wire and bringing it into the shack via the window frame never seemed an issue. Fast forward to 2009 and with all the noise generated in a modern shack means that a coax fed antenna does have many advantages.  I am not going to enter into the variable resistance of random wires across HF and is 4:1 better than 9:1 – there are many sites on Google that cover this subject with much greater flair in technical depth that I could ever hope to.

Going back 15 years I was at a rally where the RF systems HF balun was for sale – and after reading some “spin” about the product and then seeing that in the very noisy hall signals were in fact not so masked by noise as at other stands where the antennas were directly fed into the radio. This stand was using a balun and a direct feed side by side where you could switch between them. Most interesting to me at the time! I had my first HOKA Code30 and a PC and a very nice (at the time) 17” screen – all which generated a larger amount of QRM than I really wanted. Enter the RF systems balun. A quick £40.00 later and I was the owner of a very small round item that would cure my shack noise on HF, wonderful!

A quick change in antenna layout at the QTH meant now my 40meter wire was fed with the balun and at the time some pretty decent double screened RG58. Quick tests showed that it was better, and yes the noises that splattered about HF were in fact gone! Well worth that hard earned £40.00. And has ever since then worked very well from QTH to QTH my trusty balun has always fed the random wire into the shack. 

This brings about today’s thinking - is my RF systems balun the best there is? Are there better baluns? Could I change it and notice a difference? Well they are some very good questions I asked myself! And you too should be asking yourself! Could my balun be good but could it be better?

A Google for baluns and peoples comments led me to have a look at the Wellbrook UMB. Now these are just a little more money than the RF systems balun but and it is a big but. I am so impressed with my Wellbrook ALA330S that I was already convinced that if they can make a loop that good surely they could make a better balun?

A quick search on eBay and volia! I was the proud owner of a Wellbrook UMB. Comparing the two physically the RF systems balun has an SO239 one end and a twisty on pole/stud the other end for the antenna, the UMB has a BNC (ugggh) coax connector and two twisty pole/studs for earth and the antenna.

Swapping the first balun out for the other was easy, I already had an earth running up to the body of the SO239 on the RF systems balun which was unwound from the coax and then connected to one pole of the UMB and the antenna swapped over to the other connector. The coax was terminated with a PL259 and not wishing to unsolder this I used a SO239 to BNC adaptor – I know not ideal but it was a test ok!

Before the change over I took three screenshots from Perseus with a spread of signals around LF and MF which I always find are a good test. I’ve added the screenshots in order which are before and after. Have a look and see what you think. I’ll do some more tests later on with the HF bands when there are actually some signals to test against. QRM wise I am pretty lucky that a quick sweep of HF shows they are more or less identical in the reduction of the local noises I have here.

Medium wave 1.6Mhz spread RF systems balun. (fullsize in the gallery)

Medium wave 1.6Mhz spread Wellbrook balun. (fullsize in the gallery)

If you check the qallery you'll see the rest of the screenshots taken this morning.

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Since the wider bandwidth recordings for Perseus have been available there have been users who have suffered the dreaded "Audio Stutter" during playback. This either sounds like the audio has stuck in a very quick loop or the audio pauses for awhile then resumes.

So; let's see how we can tackle this. First off we need to ensure that we are really looking for a problem. Check to see if you can record lower bandwidths without issues. Let's assume anything up to 800 KHz is fine. Yes/No if no then you're going to have to look at issues like is the PC up-to making recordings and playing them back - A 800Mhz PIII with an old IDE drive is probably never going to do the job you want it to! Perseus LIKES modern hardware, remember here the software eats CPU cycles and disk IO when playing back very large files, you'll need your PC in tip top shape to work well.

So a check list of the PC "newbie’s", Is your CPU single or dual core? Dual is better. Is the CPU speed above 1.6Ghz?. Does the PC have IDE or SATA drives? SATA are much better at reading large files, IDE is *ok* but really you need to ensure your recording to and reading from a SATA drive if you have one. Are you using a laptop? Remember a laptop from the "box" is designed to give the longest battery life not best performance.

You'll need to delve into the BIOS settings and make sure that any power saving options are "Off" or "Minimal" AND if there are options for the speed then set these to "Fast" or "Performance". Once you've got those pesky battery saving options off you'll want to tell Windows that you’re a power user and not worried about battery life!

OK. Lets start in Vista. Open power options by simply typing Power Options in the search bar from the start button. Or, go the long way and, click the Start button / Control Panel / Hardware & Sound / Power Options. Click the radio button next to "High Performance" then click "Change plan settings" then click "Change advanced power settings" to continue … Change "USB selective suspend settings" and "Turn off hard disk" to "Disable" and "Never". Once you have made these changes click "OK" to dismiss the dialog box and then close the power settings applet from the control panel.

For laptop and desktop PC users they are probably the most important things to change. You can always have a fiddle with other options if you want to - if you get into a mess you can always choose the "Restore plan default settings" and you'll be back where you started.

For Windows 7 users (I know RTM is not here yet but a-lot of people have RC1 or have access to the RTM from MSDN or TECHNET so you might be using it now as your main OS) the procedure is the same. For Windows XP users click Start, click Control Panel, click Performance and Maintenance, and then click Power Options. In the Power Options dialog box, you set options for a power scheme. Windows XP comes with several preconfigured profiles. From the drop down list choose "Home/Office Desk". That's the one that offers the least power saving and maximum performance, which is what we want for Perseus recording. Don't choose "Minimal Power Management" which is misleading as this leaves the chipset and CPU to decide for you what power scheme they want to use and it is not a minimal power profile!

There are many articles on the web about power management and Google is your friend for XP, Vista or Windows 7.

Right, we have the power management sorted, moving on lets see what else we can tinker with. Under Vista and Windows 7 there are some options to improve the hard drives performance, lets have a look at them.

1. Open the Control Panel.
2. Click on the Device Manager icon.
3. Click Continue button for UAC prompt.
4. Close the Control Panel.
5. Click on Disk drives to expand it.
6. Right click on your hard drive device listing and click Properties
7. Click on the Policies tab.
8. For a ATA (Parallel) or Serial ATA (SATA) Hard Drive -
    A) Check the Enable write caching on the disk box.
    B) Check the Enable Advanced performance box.
9. For an External Hard Drive -
    A) Dot Optimize for performance.
10. Click OK to apply. Windows will require a reboot for this to take effect.

Note there is an increased risk with these options that should your PC or laptop lose power then all the data in memory due to be written to the hard disk will be lost. For a laptop user this may not be an issue. As you have a battery to fallback on but a home PC should be on a UPS (even a small one) if you're going to set these options this way.

You've been warned!

There are however some external options that can be explored. If you want better performance for recording and playback one way is to get an external drive. This can be USB2 or eSATA* it does not really matter the choice is based on what your laptop has for external connections OR what PCI card your desktop PC can take. All modern machines should have a USB2 port - that's want you want to use - in fact if you're using a Perseus YOU must have a USB2 port for it to work properly.

If you're buying an external drive then try and get one that needs its own PSU. They are faster than ones powered off the USB bus. You'll find they are normally a faster drive than the bus powered ones and that they normally have larger caches (which are important) and you get the advantage they are not sucking valuable USB power from your laptop or desktop PCs internal USB hub!

As for choosing an external drive look for these three features. The drive rotation speed needs to be 7200rpm (and not the older slower 5400rpm) make sure you get a cache size that is at least 16mb and most importantly a USB2 interface not 1.1. If you're getting one that is externally powered you should shop about as several do come with linear power supplies and not a switched mode supply and this will help keep shack RFI down.

As for what to get, I'm not going to promote any particular drive or drive maker but the Seagate ST305004FDD2E1-RK works well ;-)

* If you have an eSata interface then the rules are pretty much the same as for USB2 drives. A quick Google shows the 1TB Freecom 29416 would be a very good choice as a starting model to shop about for and good to compare specifications with. IO performance for eSATA should be better than USB2 but this should not be a reason to boycott USB2 in favour of eSATA. eSATA does cost more and you have fewer options in the market place to choose from.

Hopefully we are on our way now to getting reliable playback and recording with your Perseus!

In part 2 I will go over running Perseus in "high" mode, changing some registry settings, checking on what else your PC is running in the background that you may not need and setting up a new login profile with minimal options enabled that will offer a small working memory footprint and run only the most essential Windows services and programs at start up. Stay tuned!

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If you're looking to power the Perseus hardware solely from USB then you've probably come across USBs 500ma power limit and either had the hub shut-down or the Windows error message relating to too much power demanded by the device. Well there may be a way around this. Armed with two semi common items I have found of the 'net it seems that for /M or /P operation you can get away with a laptop and a dual power USB lead.

The two items in question are dual power USB lead/hub and the 2.1mm USB power adaptor. Armed with both leads you can draw 1000ma from two USB ports and power the Perseus hardware without an external supply which means you could then go - truly portable - to a quiet location and DX for as long as the laptops batteries can supply power to both devices. Even then there are about some 13200ma/h external laptop battery cells that would probably give at least a few hours at 125Khz / recording / DXing. I have the 2nd lead on order and will let you know how it works out.

If you're running a PC with Perseus and you want a little extra control over the 'radio' tuning then the Griffin Powermate is a fantastic multimedia USB device to use.

You can set the Powermate to tune up and down and move the tuning steps in the display window in the Perseus software.

Under Vista if you're running as a 'User' with UAC enabled you may need to right click the start-up short cut and choose 'Run As Administrator' for it to work properly. Make sure you also download the latest drivers from the Griffin website. The ones on the CD that come with them (even now) are older and do not work under Vista properly.

To set-up the Griffin to work with Perseus follow these steps:

• Open Perseus.
• Right click the Powermate icon in the taskbar and choose 'Powermate Editor'.
• Click 'Applications' then click 'Add'.
• You will see perseus in the task list, click it once, then click 'Ok'.
• Then highlight perseus in the left hand Applications list and setup the options for the wheel as the below picture shows:

Once you have the same as above just close the Powermate editor window. Your settings will be saved.

Now go to the Perseus software and focus the mouse over the main FFT window. Once done the Powermate wheel should tune up and down in the steps you have chosen as the default for the mode you're using.

To change the step move the mouse cursor over to the frequency display and then hold down the Powermate while tuning the wheel - the mouse will move left or right and that's how you choose the step - release the middle button and then the wheel should tune the digits up and down that you have highlighted.

It tales some getting used to! But is worth the effort if you need the feel of a real knob to tune. In Windows by default the Powermate wheel does the volume up and down, a short press to mute and a longer press to sleep or hibernate.

The latest Powermate (XP/Vista) drivers are located here and there are some listings on eBay here should you fancy getting a hold of one or try your local PC retailer. Note: You can get a black or a silver Powermate - they are both the same just the black one is a little more expensive and MUCH harder to purchase.

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If your like me and have to operate an HF radio near a PC (or PCs) you are always on the look out for things that make noise, either in your shack or around it.

I had noticed a noise that was pretty wideband from 12Mhz up to about 40Mhz which came and went in severity. First off this looked like it was external to me. I had a wonder about the local area with a hand held radio when it was at its peak.

Now this was a 24/7 noise so it was pretty easy to DF ... After a while it seemed to be me causing this to myself - I could not find anything external to the shack so I decided matters needed to be resolved and I was on a mission!

After turning off all non radio devices it was still there, so I moved to the shack - tuned my hand held to 24.650 AM (which was very strong) and moved about the room slowly unplugging things using walwart style mains adaptors - still no change - good!

So deciding it *must* be one of the computers I shut the PCs down one at a time - BINGO! the last machine to power down and unplug stopped the QRN.

Now I thought I would remove all external connections and power it back up - the moment it rang thou the BIOS the noise returns - ok, then it must be this PC and something inside it.

Armed now with the machine and my hand held I probed the antenna about the case - as it neared the PSU the buzz grew, after removing the case and trying again - it was confirmed the PSU was making huge amount of HF and low VHF QRN.

Lucky for me I have a few PC parts about, so a quick change out to a cheap as chips 450w PSU and the result - 0 QRN from the shack PCs again.

Now this *noisy* PSU was not cheap, do not get me wrong it was not a value part by any stretch of the imagination, it was branded and well made and only three weeks old!

So if your being troubled by a strange modulated buzz from 12Mhz onwards every 100Khz then check to see if your PC or a PC near you have a Hyper Type R PSU - if so it may be to blame.

They are black with a silver 12cm fan and the come with CB microphone style output connectors - the old four pin screw up type - very easy to recognise. The picture above is the same as the one I have that was very noisy, it will be interesting to see if others in the same range are as bad as this one.

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If you're in the market for some new speakers for your computer (the one that is running a PERSEUS) you can do no worse than the MS20 monitor speakers from BEHRINGER for just under £75.00 / $100.00 you can improve your all round listening experience in one quick upgrade. These really do make the PERSEUS audio come alive (in fact any audio). And as they are shielded you're not adding to the rooms RFI levels either.

They are small form and suitable for desktop or wall mounting. One of the fantastic features these speakers offer is digital inputs (both coax and toslink) which allows you to feed them from a PC using the SPDIF output. Thus bypassing the D-A and A-D translation that normal speakers require.



This results in a 'cleaner' sound for want of a better way of putting it. You also get normal phone line inputs and individual volume controls per input so you can feed audio in at analog and digital and mix them both from the front mounted controls.