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Thursday, 20 December 2018

An antenna for 10-meters /m

Yesterday I was given an antenna to use on 10-meters by Mac, M0RIE, which he had left unused for a while as he used an ATAS antenna on his car up until recently, though he said this antenna is actually for 11-meters (which would certainly seem to be the case as the antenna is longer than my orbitor/springer type which is also for 11-meters, which I never actually cut down for 10 as I hoped to do as the car it was on was scrapped before I could) it does tune to parts of 10-meters, I can't remember what figures he got for SWR but on my car this is likely to vary.

My current 10-meter rig is the CRT SS9900 (a rebadged AnyTone AT-6666) which I have configured for the last current 10-meter bandplan I saw (though this rig cannot do CW so I can't use the CW part of 10 once I have learned morse code but I can still use SSB, AM and FM).

Looking at Thunderpole's website the antenna in question, which is also taller than me, appears to be one of the Sirio Hi-Power antennas though there is no label on it, it is fitted to a very familiar magmount, a Sirio Mag 145 PL which I already use on the car myself for my Diamond NR770RSP for 2-meters and 70cm.

As I would like to put this on the car in a more permanent fashion I need to figure out next, by looking at the roof, where the antenna could go, it needs to be spaced sufficiently from the existing 2/70 antenna in such a way as that both when driving and when parked the SWR is not upset on both antennas, the antenna whips around as typical of CB antennas of that size, the Diamond antenna for 2 and 70 is more rigid with a spring in the base, looking at the space on the roof of my car I would probably have to sacrifice the broadcast antenna and replace the whip on that with something exceptionally short, another hands free mic would be needed, though the mic part is OK in situ as it appears to be connected using a Phono connector I could use a switch to switch between the FTM-400 and the SS9900, both radios would still have their own PTT switch.

Power to the rig would require another relay, there's an auto parts place in town I could get one from cheaper than Halfords, and I can tap into the same loom, for power I'd have to run yet another power feed from the battery to the SS9900, though Mac did suggest I could run this radio, as he has one, off the cigarette lighter I suspect that I'd have to run it QRP which is fine sometimes but not all the time if I did this.

The height of this antenna introduces new problems, low-hanging tree branches being one, low bridges, car park headroom restrictions, a local petrol station in Richmond where the clearance closer to the shop is lower than it is closer to the road, though I rarely refuel there, and potentially one or two other issues like power lines (though these are generally high enough for HGVs to pass and this antenna would not add that much height to my car, it's about equivalent to a person standing on the roof), and telephone lines, again these usually are high enough for an HGV to clear safely.

My plan is to test the antenna static first, that involves a trip to my usual radio playground in Richmond with the antenna in the boot, a notepad, the Zetagi SWR meter as it is the most reliable one I have for those frequencies, and the dummy load to get the power levels sorted, the radio will be powered by battery, the notepad is to note the SWR curve on the antenna on my car, this does involve sacrificing the broadcast antenna but nothing that a quick trip to Halfords won't fix, I'm going to film this for YouTube as well, and while I'm there, I'll stick a CB on it as well, my trusty President Grant II, and see how it performs on 11-meters, might as well if it's a nice day and that rig can run off the cigar lighter as it's quite low power, I'm obviously not going to run the SS9900 on 11-meters as, after all, that's technically illegal, even if it can be made to work there.

Though I am taking a dedicated 11-meter rig with me the T2LT will not be coming with me because this is a test of this antenna across both bands, any contacts I make on either band will be done using the antenna I have been given.

73 de 2E0EIJ/26CT730

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