[Yaesu] help with qrm/qrn

2003年1月17日 23:51:37 -0600

Hart,
Here are some of my recommendations and comments:
I understand your tinnitus. I have a slight case of it myself, but
certainly not as severe as yours. I don't get the headaches.
Noise is a problem on HF, particularly because of the atmospheric problems.
1.) Yes, VHF/UHF FM is certainly quiet. FM is a very quiet mode.
2.) Yes, a crystal rig does tend to be quieter than a PLL synthesized rig
3.) Yes, 160 and 80 are noisier than 10, etc.
OK, how do we correct some of this:
1.) Purchase a good HF rig. The better the rig, the more immune it is to
some of the QRM products, particularly receiver IMD. That's what really
separates the low end from the top end. My recommendations would be an
FT-1000D, but that's $$$. A lower cost option, but still a good rig would
be an FT-920 or even a used FT-990. In my opinion, never buy the entry
level rigs if you care about noise.
2.) Fill the rig with good filters. International Radio (Inrad) sells some
excellent products. Expensive, but they cut down on the noise.
3.) Purchase a DSP filter. These can do amazing things. In particular,
there is a product called the "Clear Speech" speaker. It comes as both a
speaker, and you can get a stand alone unit that you can plug into your own
speaker or headphones. I played with a Clear Speech unit last year at
Dayton. Unbelievable how much the noise is cleared up and how much more
comfortable the audio is. These cost about 170ドル US. You can also get more
expensive and elaborate models such as the Timewave DSP-599zx. I have one
of those and it's excellent, but it's pricey. The Clear Speech is an
excellent value for the money and what you get.
4.) Purchase some other external audio processor. There's a number of these
out now.
In my mind if you combine #s 1 and 3, you'll probably do fine. You can get
a decent rig such as an FT-990, TS440 or similar and you'll do well. You
can even go to some of the older rigs with Permeability Tuned Oscillators
(PTOs) that don't have the PLL loops in them. Some of these include the
TS-830, Drake C-Line (VERY quiet radio), and the FT-101. These are old and
don't have all the bells and whistles, but they have very low phase noise.
I hope this helps. 
73,
Jon
NA9D
on 1/17/03 3:01 PM, Hart Engel at [email protected] wrote:
> Here is my problem, and I hope you can shed some light on it.
>> I want to get back into HF radio [phone mode] but I need to know what type of
> rig I should be looking for. I live in the city of toronto and I can't put up
> a dipole or beam so the only other antenna is a vertical one, due to the limit
> space that is available to me. I have a medical problem called tinnitus [or
> ringing of the ears] and after listening or trying to tune out the hash or
> what I call the fried egg sound [after 5min of listening] I get sevier
> headaches. So I abandoned HF all together and sold my rig.
> I'm currently on 2m/70cm and I don't seem to any problems with qrm/qrn do in
> part with the squelch on the rig. And i'm glad for that.
>> A few years ago I got into 20M qrp'ing and found the radio [mfj model] had a
> built in crystal which seemed to get rid of or lesson the background noise.
>> So I figure it may not be line noise at all but just atmospheric noise. I
> remember that the higher the freq the less the noise was. e.g. On 10M it was
> around 1-3 S units and on 160M it was around 5-9 S units.
>> I need to know what type of rig or equipment I can buy that isn't going to put
> me in the poor house or were I don't have to refinance my shorts [if you know
> what I mean]. I ask this because when I got into ham, I made the foolish
> mistake of buying what ever looked good and never even researched the
> products. So you see I don't want to make the same mistake twice.
>> I am looking forward to your thoughts on this matter, and please don't be
> afraid to ask any question that might help me. Please e-mail me off line;
> [email protected] Thanks

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)
Citizen of the People's Democratic Republik of Illinois
Life Member: ARRL, NRA
Member: AMSAT, DXCC
http://www.qsl.net/na9d <- Updated on 1/12/03!!!
"A life lived in fear is a life half lived."