Hand held radio.

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Trevor Harvey
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Hand held radio.

Post by Trevor Harvey » Wed Apr 26, 2017 12:44 pm

Good afternoon all
Does anyone know if a device exists to boost the transmission power of a hand held radio?
FTA 550L. Preferably something smaller than a portacabin.
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John Clarke
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Re: Hand held radio.

Post by John Clarke » Thu Apr 27, 2017 12:44 am

I suspect this may be rather difficult to do. Any amplifier would have to include switching for changeover between transmit and receive and would probably be quite large due to the large heatsink required for AM power. Could I ask why you need to do this and what power output you require?
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Trevor Harvey
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Re: Hand held radio.

Post by Trevor Harvey » Thu Apr 27, 2017 1:09 am

I just have the feeling that TX range isn't as good as the original Dittel 25khz black and white set was.
Ten miles out "station calling xxx say again" sort of thing.
Not to worry, it was just a thought.
Perhaps have a look at the antenna.
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John Clarke
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Re: Hand held radio.

Post by John Clarke » Thu Apr 27, 2017 9:01 am

That's interesting! I've bought an FTA 750 but I haven't fitted it yet so can't give you any kind of comparison. I'm hoping to fit the radio in the next couple of weeks.

It could be worth checking the power output as well. More or less any power meter capable or reading at airband frequencies will do the trick. If you know any radio amateurs then they may be able to help with a suitable meter. I'll dig out my power meter this afternoon and check the power output of mine.
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mikehallam
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Re: Hand held radio.

Post by mikehallam » Thu Apr 27, 2017 4:59 pm

I replaced my Vertex (Yaesu) 25 Kc's with the Y'aesu 550L at the end of last year.

The Aerial, headsets and PTT unchanged.

Some stations complain now I' "unreadable". Engine off on the ground check to Farnborough East gave '5s', but airborne many don't even complain as they get no signal at all e.g. Henstridge last Sunday and Farnboro' Main !

I'm drawn to conclude the 8.33 narrower bandwidth is either off to one side of the Rx stations (I can hear them perfectly well) or is so feeble as to make me regret dumping the previous model.

I think we've bee taken for suckers into lashing out & installing equipment not fit for purpose & of no possible use in the forseeable future as anything other than the old spacing of 25 Kc's is vanishingly small for GA.

mike hallam.

Ian Law
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Re: Hand held radio.

Post by Ian Law » Thu Apr 27, 2017 7:59 pm

I'm following this with interest, having made and installed a half wave dipole ( following instructions found on the web: http://chrusion.com/BJ7/InvVeeAntenna4ULs.pdf ) and mounted it inside the fuselage woodwork, in the hope of achieving better performance with a handheld.

The antenna uses a "Pawsey Stub Balun". I can't test it for some time, so hope it lives up to expectations. I've had all the problems mentioned with the handheld in a group owned Chief.

Ian

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John Clarke
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Re: Hand held radio.

Post by John Clarke » Thu Apr 27, 2017 11:41 pm

A pattern is emerging, and it isn't a good one!

Mike, are you using the radio in 25 KHz mode or 8.33 KHz mode? I'm curious as to whether this will make a difference. I think that, in theory at least, it shouldn't make any difference as the radio should revert to a 25 KHz bandwidth when used on our current frequencies.

One other suggestion...121.5 will remain as a 25 KHz frequency. Perhaps try a practice pan or training fix and see if D&D can hear you?

I chose the Yaesu as I've used their amateur radio equipment for many years and it's good quality equipment (as is Icom for that matter). The FT 550/750 also has a much better display compared to the 8.33 kHz Icom handheld. If it's any consolation I know of people having compatibility problems with intercoms when using the Icom handheld.

If it's rubbish flying weather next week I'll try to get my radio fitted so I can do some testing.
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Trevor Harvey
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Re: Hand held radio.

Post by Trevor Harvey » Fri Apr 28, 2017 1:13 am

I've been using my FTA550 on 25khz
I tried an A6e and got unreadable when I was on the ground and an aircraft on short final. Which was why I changed it.
At 5 miles range the 550 was 5x5 from ground to airborne both ways.
I've mostly been using the rubber duck antenna because I'm not too sure about the original antenna.
I tried it once at ten miles and got "3x3", swapped it back to the rubber duck and got 5x5, however that must have taken a couple of miles to swap over.
I'm interested in the dipole inside fuselage, may try that too.
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mikehallam
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Re: Hand held radio.

Post by mikehallam » Fri Apr 28, 2017 8:33 pm

I may have resolved one source of poor performance on the Yaesu 550L.

The manufacturer's supplied 12 volt reducer to operating voltage device is crude & it produces a lot of noise from (AFIK) chopping the a/c 12 VDC into bits and re-assembling into a crude fuzzy DC.

It's a horrible thing anyway so I chucked it out today & replaced with a proper smooth 8 VDC supply taken from the a/c 12 volts, having done a search for an easy answer on the Net.

A short test flight gave '5' s from Goodwood and Farnboro' East and thirdly a hand held on the ground, the background noise generated by the 'fuzzy' olf input volts has gone so it is much better to use.
[Even so Fanboro' Main weren't able to hear me from 1200 ft near Horsham, Sussex, but come to think of it never could.]

Cost of parts £2.44p and the device provides real 8 Volts - not chopped - DC. It works something like a centre tap potentiometer except the output remains held at a steady 8 Volts & is not load dependent.

E-bay £2.06 for a (post included) Fairchild Semiconductor LM7808CT.
Maplins cost 2 X 19 p for 0.47 uF & 0.1uF capacitors.
Connections:
A/c 12 v in on tag 1), Earth to tag 2), 8 volts out of tag 3). Small capacitor 0.47uF between 1) & 2) & the 0.1uF berween 2) & 3). That's it. Plus I did put an in line fuse and switch

mike hallam.

Seanjd
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Re: Hand held radio.

Post by Seanjd » Fri Apr 28, 2017 9:53 pm

I have the FTA750 used on the AA batteries in the unit. and aerial is external fitted.

Crystal clear RT at 20Nm.

Sean
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John Clarke
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Re: Hand held radio.

Post by John Clarke » Fri Apr 28, 2017 10:57 pm

It's certainly beginning to look as if the supplied 12V to 9.5V power adaptor is part of the problem. Today I've been chatting with someone who has the problem that neither TX or RX works when connected using this. In the next few days I'm hopefully going to visit his airfield with my radio and power adaptor and see if there's any difference. I gather that this adaptor is some sort of switch-mode device. These are well known for producing noise and, as Mike has noted, a rather rubbish output at times. This is probably why Yaesu supply a ferrite core for use with the adaptor as this should help reduce power supply noise.

Mike, it looks like you've done some good work there! If I have a problem when I fit mine I think I'll try your idea.
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mikehallam
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Re: Hand held radio.

Post by mikehallam » Sat Apr 29, 2017 11:39 pm

Did the Popham show today, all RT worked , really indicates the DC needs to be real DC and I'm happy now with the above mentioned method of obtaining it and being able to discard the one that comes with the 550L Yaesu.

mike Hallam.

dmcnicholl
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Re: Hand held radio.

Post by dmcnicholl » Sun Apr 30, 2017 7:45 am

Most interesting, Mike. I have just bought a FTA-550L to replace my old Delcom AIR 960, and this is of interest to me. I had already seen some reference to the 550's need for 8 VDC but the the manual doesn't really go into detail. Your home-brew recipe has been saved for future reference, next project after I have finalised my own home-brewed PTT switch breakout.
Donald McNicholl
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Trevor Harvey
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Re: Hand held radio.

Post by Trevor Harvey » Sun Apr 30, 2017 11:42 am

I got Harry Mendellson to chop the plug off the Yaesu headset adaptor and splice it onto a two place intercom, which has a PTT socket.
I then wired to the back of the PTT socket out through a hole in the back of the box to the original stick switch. No pluggy in cables trailing around.
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dmcnicholl
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Re: Hand held radio.

Post by dmcnicholl » Mon May 01, 2017 8:05 am

Trevor Harvey wrote:I got Harry Mendellson to chop the plug off the Yaesu headset adaptor and splice it onto a two place intercom, which has a PTT socket.
Well this is the LAA so homebuilding is allowed. :wink:
Chopping the plug off the Yaesu lead was an option but I wanted to keep that as a plan B if I cocked it up. Also, mine is a single seater so I have no intercomm, and cockpit space is tight so a custom solution seemed the way to go.
Donald McNicholl
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