UHF sets - Optimum tuning???

Hi Tony - I was speaking of the operating frequency, not the antenna. I've had this unit checked by a reputable organisation who couldn't find anything wrong with it. (They must have been reputable - they charged me only a minimal fee!) I doubt though that they checked the actual operating frequency. I don't have the calibration resources (and I doubt that many repairers do either) to check the operating frequency accurately.

Thank you for your thoughts

John

John

Go back to the people you took it to and ask if they checked the operating frequency.

As Mike suggested in Answer3, It could be overloading in the input of your receiver from close up transmitters. Another cause of this distortion can be caused by people winding up the transmitter deviation in the belief that they can make their signals louder - all they do in this case is make their signals too wide for the receiver to accept - are these sets owned by people who fiddle?

PeterD

Hi Peter,

I got fed up with this thing while visiting Alice recently and had it checked out there. I'm now home in Canberra, so, while I'd like very much to go back to Alice where it's warm, it's a bit far to go just to sort this one out!

Mike's point is of course valid, but distance doesn't seem to make any difference, so it's not as simple as overload in the RX. The problem is also bidirectional - if reception is distorted, so is transmission. This tends to rule out excessive deviation. (I'd like to put an oscilloscope on the audio - symmetrical clipping might well support yoiur suggestion. Not sure if asymmetrical clipping wouldn't point to slightly off-frequency rf.)

Are the sets owned by fiddlers? No

Thank you for your input.

John

Jim. Mike,
Thank you for your suggestions. I haven't made my origional post too clear!

This is something which has bugged me for a long time, and with several antennas, leadins etc. This weekend I've been in a convoy with a number of other vehicles, all with UHF, so had the opportunity to check out just which combinations of sets produced good, bad and fair comms.

From some transceivers I receive very distorted signals, regardless of range - equally bad at 50m, 1km and more. My transmissions to these same units were similarly distorted. With other units, I had very low audio distortion on both Tx and Rx. Generally, lower distortion is coupled with better range. Interestingly, within this group there were other combinations which showed a similar performance spread though none as extreme as mine.

I'll try to narrow it down as suggested by swapping components. I'll check (again!) the operating voltage, earthing, etc as Footloose has suggested.

Regards

John

Emmm... given the further info my guess (and that's all it is) is that your set is a little off frequency - as Tony suggested.

However because you have good comms with some sets but not with others it suggest they either have a wide front-end or are also a bit off frequency - neither scenario is unreasonable with CBs but it doesn't "feel" quite right to me - if you know what I mean :)

I suggest you bypass the dealers and ask GME to have a close look at your set.

Mike Harding

John

As you are in the ACT contact the ACMA district office at Belconnen (1300 850 115) and see if they can do a quick check on your transmitter frequency. This will check your receiver frequency as well because the two are locked together.

Failing tat you may try Watts Communications.

PeterD

Thanks Peter - I'll see what ACMA can do, and if that doesn't provide an answer, GME can have a go as Mike has suggested.

John

John
I forgot to add that I've been down this track many times here on EO with people who think they know when they have not had the oppertunity to do the tests as I have with many Truckies and other motorists, and as for any feed back other than yours I am not interested in the BS that is about to be let forth

Hi Doug,

I recall reading your Uniden comments a while back and since then I've noticed that many Unidens are horribly distorted. My issue isn't confined to them though - in the last few days my GME has communicated with quite a range of manufacturers stuff. The single most obvious effect is that if my set sounds distorted on TX to another unit, my reception from that unit will also be distorted, even though others listening in may get a good, or at least fair, copy.
John