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Improving handheld antennas

There was a small article in SPRAT, the G-QRP club magazine this quarter that is both devilishly simple and also appears to work well.

The addition of a 1/4wave counterpoise to a handheld does improve the performance of the rubber duck quite noticeably. This consists of nothing more than 1/4 wavelength of wire connected to the earthy side of the antenna connector and is allowed to simply hang down. The article suggests an 1 to 1.5 S point improvement.

I’ve tried it on my VX170 from home using GB3CS as a reference signal. It’s about S3-S4 using the rubber duck and it’s S5 with a counterpoise. Switching to a 1/4wave telescopic antenna and no counterpoise results in S4-5 as the reading is bouncing about. Using the 1/4wave antenna and counterpoise resulted in the signal spending most of its time around S6.

Myself and Brian G4ZRP used such a counterpoise along with a telescopic 1/4wave on my FT817 from Fair Snape Fell and Longridge Fell the other week as someone (me) forgot the proper 2m antenna.

For the time it takes to make and deploy and for the cost and weight penalty this is really something that everyone who uses a handheld should have with them. Easy to fit when needed and if you have a softcase for your handheld you can coil up the wire and slip inside the case so it’s always with you.

Andy
MM0FMF

In reply to MM0FMF:

I tried this trick on High Street (G/LD-011) a couple of weeks’ ago after receiving my copy of SPRAT. My VX-150 seemed a bit better on receive. The only problem was that I lost my ‘tiger tail’ on the descent!

I used some RG-174 and a large crimp connector with the two prongs (like a tuning fork). The prongs just fit around the SMA socket on the rig, with the antenna itself clamping the ‘tiger tail’ to the radio.

I must make another one and screw the antenna on more tightly this time!

73
Colin

In reply to M0CGH:

RG174 is being posh. I have a bit of PVC covered hookup wire. You can use a ring terminal of about 6mm ID (I think). Lift the rubber gasket off the SMA on the VX170 (VX150), slip the ring over the socket and refit the gasket. Then when you screw the antenna on you can make a proper contact.

Andy
MM0FMF

In reply to MM0FMF:
Hi Andy,

It’s a good mod! I have carried one from the 1st days of SOTA just in case the external 2m-FM aerial failed but never had to use it.

In the last 2 or 3 years I have started using one on 4m FM. Similar to you - I use a large ring crimp to fit the SMA and some extra-flexible silicone rubber insulated ‘mega’ multi-strand. This stuff, which I have seen used for multimeter leads, has no memory even in neg temps and will always deploy vertically without curling up.

The addition of a socket at the remote end allows the fitting of a ground spike (1/16" stainless welding rod) for when the excitement gets electric. I have an aversion to those conditions having wrecked my best handheld on Skiddaw a few years ago - to say little of nasty shocks on numerous ocassions.

In my book, to be worthy of inclusion every bit of SOTA gear should preferably have more than one use. The third use for the counterpoise is to lash the battery to the handheld when it’s unconnected. Like many other modern rigs, a connected battery on an IC-E90 starts to discharge into the rig at a low rate so I leave it off until the activation. Overnight, that could represent an extra QSO!

In thoery the counterpoise should increase the efficiency of a handheld without placing total reliance on the rig’s meagre chassis added to the capacitively coupled ‘random bag of salt’ holding it! What we need now are some tests with and without.

On another subject Andy: I read that you work with Munro experts. What a good feature to have handy. I remember when I was taking the RAE; I worked with a fellow engineer who taught the RAE course at York Tech. Added to that a professional across the road (Roy G4SSH) who could teach me Morse. Knowledge on tap. Value not to be underestimated!

73, John.

In reply to MM0FMF:

This is an idea that occurred to me but I never got around to trying it. It last came up in conversation when I was talking with someone about the trailing counterpoise that comes for use with some of the military HF sets. You have a reasonably large whip off the back of the set and trail the counterpoise behind you as you walk. It can be configured as an off centre fed dipole or a dipole depending on the band and size of the whip.

One further improvement to most handheld radios these days is to properly tune the whip using an analyser and a pair of snips. Most radios these days are wide band receive and the Chinese handies particularly may have their rubber ducks resonant anywhere between 130 and 170 MHz.

I would suggest if you intend using a counterpoise that you tune both antenna and counterpoise together using an analyser if possible.

One reason for expressing a little caution is remembering back to the old MkI Yaesu FT290 where if the telescopic antenna was removed completely then the PL-259 circuit became detuned, as one or two of my pals found to their peril when they replaced the telescopic with a BNC socket. Note: There was a BNC mod that came with a metal tube that screwed in place of the telescopic so it did not detune the circuitry, but they have been like hens teeth for years.

73 Steve GW7AAV

In reply to MM0FMF:

Yaesu VX-6E into GB3VM with stock rubber duck: 5/9 Small amount of smooth noise in the background.

Same condx with “tiger tail” (what an annoyance of a name!): 5/9++ (well, two more bars after 9 (“end stopping”) on the guess meter. Smooth noise almost eliminated.

The only problem is the raised rubber seating around the SMA this submersible handie - makes it hard to connect a wire, and even worse to use a forked connector - perhaps some careful bending with the pliers might help!

73,
Dave M0MYA.

In reply to M0MYA:

I’ve just looked at a VX6 picture. The gasket looks identical to the VX170. Lift it up, slip ring/fork over SMA, refit gasket. Gasket should hold counterpoise in position and contact with SMA.

Job done.

Andy
MM0FMF

In reply to MM0FMF:

I made one of these last week for my Yaesu VX7-R & tried it out today while on Pendle Hill & it does make quite a difference. I was using a 38cm flexible dual 2/70 whip with 1/4 wave counterpoise for 145MHz.

After I had descended I came across M3ZKU/P on 145.550MHz walking over G/NP-008 Great Whernside working Mike G4BLH & he was also experimenting with a very similar setup to mine. At one point he dropped his TX power down to 0.5 Watts & was a readable but scratchy 51, with the counterpoise attached he was much clearer with the white noise much less, although the meter on my VX7-R didn’t indicate much difference. With his power at 2 Watts the difference was an improvement from 53 to 56. I was stood at the side of the road in the usual parking spot on Barley Lane for G/SP-005 Pendle Hill.

I will be certainly be using the counterpoise again next time I am out & about.

Best 73,

Mark G0VOF