How long is a piece of wire ... for SSB antenna?

Hello Shy Talk,

Do you know of any pocket pc software that will allow weatherfaxes to be read via SSB ?.

Thanks
 
a quaterwave forget!No good at all!

You are asking about a receiver much easier than a transmitter!!The antenna for a receiver had other needs!! If its to long youll pick up all the crackel and pop!If its too short poor reception!So how long should it be?

Good question!IF your new receiver has DPS then as long as possiable!!If not buy a DPS filter. I was useing one this weekend i bought it about 10 years ago!And only just discovered how to use it! I read the instructions!!!

Its easy! Just set the controls as in instruction book then push notch or dynamic peaking filter,then take them out and try the the noise reduction knob
untill theres a good signal!

I was makeing a test i asked one station to tune(send a carrier) and another to speak! when i notches and adjusted the carrier went then with the dyna peak the static went!What was left was a clear signal!!

I pressed my TX and went QRT. Now i need a new rig but it was becouse mine was very very old and very very rusty!

You can find a NIR-12 from jps communications.inc for a couple of British pounds second hand.Most rigs have DPS today and the NIR-12 wasent popular becouse it you had to read the instructions first!!!???

To be fair it can take out the signal but you have to adjust it the rig i had was so good it dident really need it!It was a luxury!
 
The formulae is 300 divided by the frequency in MHz and the result is in meters for each full wave.If you want a quarter wave aerial then this would be a quarter of that length (obviously). This is the speed of radio waves (300,000,000 Meters each second), divided by the frequency in Hertz and the answer is conviently in Meters .
 
(all freqs approx)
Problem is that its not going to be used on a single frequency. You are going to want 2 Mhz for CG, 4 8 11 Mhz for wxfax and rtty, 5.5 for shannon, 12 for herb (god knows how long for the swmbo to listen to R4 on 198k). I spent ages trying to work out a length that would suit all these. Finally gave up and said to the rigger "just stop 3m short of the mast so it doesn't get struct by lightening, and 2m up from the deck so I don't get fried" and I take up the slack with a tuner.
 
For receive only use the longest and highest length of wire you can.

Connect it to your receiver via a tuning unit.

You can get a simple atu for receive only for about £25

People will tell you not to use an atu for a receiver and they will be wrong.

They will be even wronger if you use the set for digital reception such as RTTY, Metfax etc.
 
I've been lurking on this one since I've also been thinking of fitting a Nasa receiver for weatherfax etc. Do you think that simply connecting to the uninsulated rigging (via a atu) would be satisfactory, or would a "proper" insulated backstay as per TX be required? I presume that taping a long insulated wire up the backstay or a shroud wouldn't do - or would it?
 
OK agree with the atu but it can reduce the signal strength?Cant it? Sounds less loud when tunes to 1:1 than before on receive.

Why??
They will be even wronger if you use the set for digital reception such as RTTY, Metfax etc.??

I dont know the nasa i thought they were sold to get RTTY WX?
 
Yes

It does sound quieter that is because you are presenting a 50 ohm source to the input of the rx.

Without tuner you present a higher voltage because of the reactive source. It sounds louder because of the higher voltage but most of the extra voltage is actually noise.

You also have a better chance of avoiding image reception. Most receivers today have little or no selectivity in the front end and so present a broad band of frequencies to the mixer(s) before the IF filtering - all this contributes to noise.

Including an ATU means you put a selective stage in front of the mixer(s) which reduces the noise power being presented to the selective stage.

What this means is that you get a better signal/noise ratio I did some checks last year with a 35ft length of wire and my atu (MFJ) produced an improvement in S/N ratio of 6-8 dB measured on the S Meter of my Yaesu. That is a significant improvement.

With any digital system the S/N ratio limits the rate of flow of information. With a bi directional system this will result in the xmission speed being reduced by the error handling system. With a one way fixed speed radio system the result is a loss of information. If the S/N ratio is bad enough the error rate will be bad enough to cause a loss of synchronisation and the received "picture" being illegible.

The NASA is a relatively low cost receiver - I have never used one and I suspect with your experience you would be looking for a more sophisticated piece of kit, but it does come with a good reputation.

To Dave:

For reception that will work fine.
 
Thanks for the reply. I fear I have confused myself, however, by actually posing 2 options! Am I right in thinking that your view is that my first suggestion, i.e. connecting directly to a shroud or stay, would be OK?
 
I've never tried connecting directly to the rigging.

Assuming it has a degree of insulation from the sea it should work although my gut reaction would be to use a separate length of wire.

Perhaps try both - see which works the best - my bet would be little difference.
 
I used the chain plate to conect the antenna to a lowe the Sony SW 55 woorked really well

Understood! Would you prefer a kenwood 440s or Icom 706 mk2?

Im useing a 30 foot whip with a base coil which is 13 feet of wire around a 2 1/2 inch PVC former. (I think i wound 13 feet??We were wine tasting at the same time the length was right i cant remember if i was told 13 feet! I asked someone if they could calculate the winding for base loading)

On another boat i lashed with tared thread a wire on the back stay it looked well done, which was the antenna to my old sailor receiver that got BBC! and many other statins really well.

On my last post i hadent understood the answer as i was standing outside a hotel with wi-fi and saveing to firefox scrapebook to read abaord.I should have waited untill i read it properly to answer as he ment "You better have an ATU for RTTY & digital" but the nasa would do that. And as i see an ATU be better added!

My antennas set for 3500mhz

Once again im standing outside sending this!! I missed a post!

Yes to both! A wire up the back stay works and the chain plate or backstay fitting better!

That was on a Hillyard with a wooden mast so side stays were conected at the mast head to back and fore stays!You will have to try both and see which gives the best reception on your boat! Good luck!

Oh and if theres thunder about the energy can do your front end a power of harm even when off!!Better remove the antenna form the radio during thunder
 
thanks for all the answers.

Based on the old engineers adage - if all else fails read the instructions - I just checked the Nasa website.

The destruction manual for the radio says it comes with 30feet (about 9m) of antenna cable which is a good compromise.
 
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