Tuesday, 2 August 2016

Clansman Manpacks for Amateur Use - Part 5b

PRC-320 HF Antennas

No mucking aboot, straight into it! For HF, were talking wire! At least, mostly...

SO, you have spent your hard earned shekles on a PRC-320, but been slightly taken in and its body only. You've collected up a battery, and a handset, now you need an antenna,

The basic starting point is the whip. This is an interlocking sectional antenna 2.4m long. However, it cannot be used directly with the radio, instead it requires an antenna gooseneck adapter. This is a hefty spring with a circlip secured hole for the whip, and a rod for the antenna socket of the radio.

PRC-320 Antenna Gooseneck adapter
Just like the one above, which incidentally im selling on ebay [eBay item number: 272308793412] for a very competitive price. This allows you to position the whip at various angles as required.

All well and good, but you wont get very far on just the whip. Thats not to say you cant make contacts - I had a QSO with a German station on just the whip on 40m from my workshop, and Bob M1BBV did rather well into the States on it on 10m. But, there are ways to make it better - Groundplanes!

The top one is the cheapest, but also a bit fiddly to use. A short wire connects to the -320's ground stud, and the four 9m long wires are unwound and laid out in a cross around the radio. The lower spool is a more up to date version and each wire is on its own little spool.

Now, you cant help but have noticed, unless your set hasnt got one, that theres a tuning chart on the radio. This tells you the settings of the built in TURF (ATU) for various antenna configurations. You will notice it gives values for the 2.4m whip, but also 5.5m and 7m verticals, end fed wires, and dipoles. Ah, dipoles, so now you understand why theres a removable coax link on the back of the rig!

Lets stick for now with the verticals. Remember that odd bit of wire with the 5.4m mast kit? Pop it on top of the mast, and thread it through the little hole in each of the guy plates. Now, look just below the antenna socket on the radio, theres a little spring terminal. Press it, and stick the pin on the end of the wire in the little hole - voila! You now have a 5.5m vertical antenna! You should, of course, be doing this with the above groundplane also attached.

So, whats the 7m vertical mentioned? Well, before putting the mast up, stick the 2.4m whip into the hole in the little tube that the wire is attached to on the top of the mast- 5.5 + 2.4 = er, about 7m!

With your PRC-320, you should also have obtained for yourself a 20m coax lead, a dipole center, and two spools of Clansman braided antenna wire. From these, come your end fed and dipole options. Notice that the wire on the spools has various colours and numbers of tie-wraps on it - these are length markers! Unwind the amount of wire needed according to the tuning chart, pass the end through the hole on the dipole center and into the terminal (or direct into the radio terminal if an end fed), pass the wire at the spool end through one of the tight slots on the spool, to stop it unravelling. Thats your antenna element. Do the same with enough of the cord to pull the wire up over whatever support your using (if that the 5.4m mast, then thread the cord through the guy plate holes and around the tie-off plate).
Antenna wire spool
I wont go into all the dipole and end fed antenna variations possible, as these are all in the back of the PRC-320 user manual, which surely you have downloaded and read by now? No? well why not?

For most of the antenna systems mentioned in these posts, if you trawl back through this blog you will find example pictures. There are also 8m and 12m masts available, but those are getting a bit too unweidly to be classed as man portable!

And, really, thats about it! From this short series of posts, hopefully ive explained the basics of getting set up to use these fine green machines for amateur purposes.  I dont intend any specifc posts about actually operating them though! Working that out for yourself is part of the fun! I will however, do one last post, no. 6, if you have the stomach for any more, and just mention a few of the other little bits and bobs you'll find you cant live without!

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