I have a Yaesu 550 which has never been great, but wasn’t as bad when I got it as it seems to be now. I sent it back to the factory at one point shortly after I bought it: they were helpful and sent me back a ferrite to install on the adapter which helped a bit, but if truth be told I was never entirely happy with it.
Once, early on, I managed to raise Hawarden and they could clearly hear me well and vector me through their airspace – so it must have been working relatively well when I bought it. A little later I flew to Blackbushe and whilst it worked OK within the circuit, by the time I was a few miles away I lost contact. I couldn’t even change over to Farnborough.
Right now, I seem to manage to get reasonable reception, but the transmission is awful to the extent that I think it is a safety issue. People can’t hear me clearly even from the circuit. I hear myself OK, so I think my headset and the connectors are working properly.
I don’t think that even at the outset it ever worked well enough to transmit clearly from the far end of the runway (800m), though there is a metal fence in the line-of-sight. My aircraft is wooden.
Things that have changed:
I have changed my ignition wires from Carbon to copper core, which is meant to be kinder to the mags and I think helps with starting. However, it does make more noise. I would have thought this should affect reception more than transmission.
The charger has gone AWOL so I have been using the AA battery pack rather than the Lithium pack that came with it. I have tried Ever-Ready Energiser Max batteries which are meant to work better in low temperatures. This might have helped slightly.
I have done a fair amount of work trying to make an external antenna in an attempt to gain a longer range. At some points and some frequencies, it wasn’t very well matched to the transmitter. I might even have pressed ‘transmit’ once or twice with it disconnected. Still not ready to install. I suppose it’s possible that I’ve broken the radio whilst playing.
I bought it slightly before we changed to 8.33khz channel spacing, so originally I would have been using it in a different mode.
It has knocked about in my bag for a fair bit and the stub antenna is slightly bent.
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As I see it, my options are to play around and see if I can make it work better by trying the lithium ion battery again, or by buying a new antenna. All of these options involve spending money, and as my suspicion is that the problem is with the radio its self, I don’t want to throw good money after bad. Perhaps relevant, I shopped around for the radio and it arrived with an Euro plug, so I think I probably got a ‘grey market’ version – perhaps it had already been returned.
Am I right in suspecting that the radio has never worked as well as it should have? Is there anything else I can try before splashing out on a replacement? I think I may have been too forgiving of it, as I never expected it to perform as well as the installed higher-power radios I was used to previously. What should I be able to expect from a radio with a stub antenna?
Yes, I have one, works ok but don’t expect much on tx with the provided stubby antenna. I have a fixed external antenna( disused ELT) and it works reasonably well. The power output is, of course, much less than a “proper” installed radio.
The range of handhelds is limited unless using a rooftop antenna. You might get 10-20nm but it will depend heavily on the aircraft – same as the performance of GPS receivers in phones and tablets depend heavily on the same.
I used to have a “loop” in the COM2 antenna connection and a means of connecting the Yaesu (previously ICOM) radio into that. Recently removed due to lack of space for two RF connectors.
Interesting about carbon ignition leads. Didn’t know they existed. Probably, as you say, not much good to the magneto because the magneto ends up producing a higher voltage before the spark gap breaks down, so stressing its insulation more.
kwlf wrote:
The charger has gone AWOL so I have been using the AA battery pack rather than the Lithium pack that came with it.
I believe the Yaesu will charge the lithium battery pack via the “ext DC” port on the side of the radio. Slower than the base, but still.
All handhelds used on our club field seem to have aftermarket antennas installed (instructor watching student solo, parachute control person), or are hooked up to a fixed base antenna (eg. glider control trailer).
Yes you can charge it. Needs something funny like 10.7v which I guess is easy enough but involves ordering connectors. For the cost of my time I figured it would be easier to order a new charger but got sent the base station instead!
Do you mean that you replace the short stub antennae with a longer directly attached antenna, or a larger installed antenna? Is there any in particular that you would recommend? Could be useful with a new radio even if it didn’t work out in the short term.
A 1.5 Watt radio with a rubber duck is not likely to acheive any more than you are getting. Connect it to a proper quarter wave antenna with a ground plane and you might get somewhere.
Larger installed antenna connected via coax and BNC connector
kwlf wrote:
I have done a fair amount of work trying to make an external antenna in an attempt to gain a longer range. At some points and some frequencies, it wasn’t very well matched to the transmitter. I might even have pressed ‘transmit’ once or twice with it disconnected. Still not ready to install. I suppose it’s possible that I’ve broken the radio whilst playing.
Some of the Yaesu amateur band radios are notorious for frying their transmitter finals if a badly matched antenna or worse, no antenna at all when the transmitter is keyed up.
However, if you know any radio hams, they’ll usually have a power meter which can be used to make sure the transmitter is indeed transmitting at rated power.
Hmm…
Bought myself a cheap SWR / power meter and built a ‘bazooka’ antenna that gives me an SWR of 1.5-2 across the band and a power reading of about 1.5 watts.
The SWR reading on the rubber duck antenna that came with the radio is about 25-30. I wonder whether that’s how it normally is, or whether there is something wrong with it e.g. a wire broken inside.
I don’t think I can fit the bazooka antenna in the aircraft, but next time I’m at the airfield I’ll walk to the far end of the runway and see whether it works better than the inbuilt one. It will tell me whether I’m on the right track, at least, and might save me from needing to buy a new radio.
I have been wrestling with 4NEC2 to design something that will fit in my aircraft and have the bandwidth required for airband radio. All I have managed so far is to give myself a headache.
SWR of 25-30 means something is certainly broken in that antenna.
It becomes a bit clearer if instead of SWR you think in terms of return loss (where high values are good – return loss means that for a given input, how much of it comes back. A perfect match (which never happens) would mean an infinite return loss (and a perfect open circuit or short circuit would give 0dB return loss).
An SWR of 1.5 means a return loss of 14dB. In other words, if your transmitter is outputting 1 watt, only ~40mW is being reflected back and not absorbed by the antenna.
An SWR of 30 means a return loss of only 0.5dB. If your transmitter is outputting 1 watt, 900mW is being reflected back (and only 100mW being absorbed by the antenna).
As you can see from this, an antenna with an SWR of 30, or return loss of 0.5dB is most definitely broken.
