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   Home   Help Search  
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 41 
 on: Today at 05:06:13 PM 
Started by HAMSTUDY - Last post by G3RZP
there's about 3.5 dB difference between a 75 ohm rx and a 50 ohm rx. What is the input SWR of an rx? Probably under about 3:1 so the difference in reality is pretty negligible. BW is an SSB bandwidth of around 2.5-3.0 kHz. This is another of those areas where tenths of a dB and even halves of a dB are pretty meaningless. The best one can do is look at the spread in a given percentile.....now look up the statistics books to go further into it: I failed math at that that level, having had an awful lecturer who wanted us all to buy the text book he had written.....

I never was good at mathematics: the best lecturer I ever had was one who admitted that he had always had trouble understanding maths himself and so could understand when we had troubles with it......

 42 
 on: Today at 04:47:12 PM 
Started by M6EES - Last post by N6YFM
Thanks again...but it seems I'm not done yet  Undecided

Again everything is totally fine on 20m....

But on 15 meters ....with low power of 5W and on very low speaker volume and very low menu 76 settings I can hear the tones on my other radio coming through fine. But as I slowly edge up the speaker volume and menu 76 settings things start to distort long before my power meter on the 3000 gets anywhere close to indicating 5w. I'd say I get to about 3w output before this 'grating' noise starts and any higher it goes crazy makes horrible noises and HRD shuts down. And it's before the ALC kicks in too.

On 10 meters it's worse....I only get clear tones on the listening station if I have the PC on very very low speaker volume and very low menu 76 settings in the 3000. The PO meter shows zero ( guess milliwatts of output)...any higher on any of the settings and the distortion takes hold.

On either 10 or 15 meters if I try to get the power out up by turning the carrier power up the same thing happens...mega distortion and HRD shut down.

I guess at least I have proved that the soundcard in the radio is working. And given this gets worse at higher frequencies I am starting to think this might be some sort of RF issue....my antenna is just an end fed random wire out the bedroom window, with the balun actually inside the house !



OK, progress is being made.
We have ruled out any further soundcard settings, and can now with reasonable certainty zero in on
high SWR and inadequate common mode choke as causing both power foldback protection in the amp,
as well as stray RF hitting your rig and shack and causing USB disconnect from HRD.

You mentioned an end fed wire antenna with balun.   Are you trying to use the internal tuner in
the Yaesu rig, or do you have an external tuner capable of the more than 3:1 mismatch that an
end fed wire can show?

I am no expert in end fed wires and do not use one, but from what I do read, you will frequently
get common mode RF coming back down the coax shield and hitting the rig.  And they also can
display greater than 3:1 SWR on certain bands, depending upon the design of the wire antenna
and length.

Your remaining symptom has nothing to do with the soundcard.  The fact that it works on 20m
and not another band, tells me that your SWR is climbing on the higher bands.  If it gets above
an SWR of ~3, your internal tuner can't hack it (are you activating your internal tuner?), and you
would want to be looking at an external LDG or (cringe) MFJ tuner (or any other brand you like).

Have you tried connecting an SWR meter and taking a look at where things stand on each band you
wish to use?
When you say that as you turn up audio out and the menu for data mic gain, you start
getting distortion, yup;  The rig does not want to create much power into a high SWR.  
[As Bill Murray said in the Movie GhostBusters;  "That would be bad".]    So if you
adjust the audio input above the top safe limit, it just starts distorting and clipping the signal but not
putting out more RF power.   Even though your RF amp can't create more power given the antenna
mismatch (and built in protection circuits), the over drive of the audio and the distortion will be seen
as RF splatter across the band.

Your Yaesu 3000 has a built in SWR meter.  Using menu settings, you get to see EITHER the
SWR or the ALC, not both :-)

Take a look (either with the internal SWR meter, or an external meter) at your SWR between
your antenna and your Yaesu.    I am guessing you will measure a high SWR on bands other
than 20m?  

So again, in summary, we have two remaining problems I suspect are the likely problems you
are having;

1.   Antenna mismatch causing high SWR on bands other than 20m.

2.   Lack of a common mode choke on the antenna line where it comes into your shack/rig.
http://palomar-engineers.com/antenna-products/1-1-balun-kits/choosing-a-feedline-choke


Let us know.

Cheers,

Neal

 43 
 on: Today at 04:43:14 PM 
Started by KZ7ZUL - Last post by KZ7ZUL
Hmmm ok thanks

 44 
 on: Today at 04:33:55 PM 
Started by KE4XJ - Last post by KD8MJR
Yes I am looking for a SS Amplifier To replace my SS THP 450b. I would like to have legal limit power when I need it.

The SS THP 450b has been very good and interchangeable between HF mobile work and now sourced to my home station.

I was able to simply plug my THP 460 (A Tenma version) power supply into 110vac. the amplifier is impressive and does not pull much more than 7 amps off my AC mains.

So I am shopping.

73

If i didnt own one already I would buy this in a second.  One of the most reliable legal limit SS amps ever made and the form factor is smallest ever made.  Will do 1800-2000W but not recommended to exceed 1500W  .

http://www.ebay.com/itm/TOKYO-HY-POWER-HL-2-5KFX-LEGAL-LIMIT-SOLID-STATE-LINEAR-AMPLIFIER-SUPERB-/222133939488?hash=item33b836ed20:g:1loAAOSw7ehXR2t-

73s
Rob

 45 
 on: Today at 04:32:03 PM 
Started by W9OY - Last post by N0YXB
I was a Flex owner.  Had a 6300 and then a 6500 and got rid of them and glad I did. 

Sure you did. Bet you own a couple of Lamborghinis too.  Roll Eyes

YXB, yes I did own a 6300 then returned it within the 30 day period and upgraded to a 6500 so don't tell me what I owned. Sorry that you cannot afford to buy a Flex but some of us can.
I probably will buy a Flex some day. Still don't believe you though.

 46 
 on: Today at 04:14:08 PM 
Started by W9OY - Last post by K9IUQ
Anyone actually know someone who has taken the challenge?
73
Steve
K9ZW

I actually doubt that no one is that stupid here on the eHam SDR forums. Try asking the question where the truth is censored - Like QRZ or the Official FLex Forums...

Stan K9IUQ

 47 
 on: Today at 04:13:10 PM 
Started by KA4AQM - Last post by KA4AQM
Besides MFJ and Ameritron, does anybody make a very good remote coax switch for up to 4 antennas?

 48 
 on: Today at 04:10:00 PM 
Started by K5TED - Last post by K9IUQ

BTW got some time with a IC-7300
73

Steve
K9ZW

Yeah right, did you have W9OY's "This Buddy" guy let you try one out?   Wink Cheesy Cheesy Cheesy Cheesy Cheesy

BTW I got some time with a Flexradio 6500 and and it did not change my mind. If it requires a computer or $1200 Maestro to operate it ain't gonna be in my shack. YMMV.  Cheesy Cheesy Cheesy Cheesy Cheesy Cheesy

Stan K9IUQ

 49 
 on: Today at 04:04:32 PM 
Started by KC8MWG - Last post by AA4PB
True.

 50 
 on: Today at 04:03:09 PM 
Started by KZ7ZUL - Last post by AA4PB
Maybe someone is just transmitting a carrier (CW - key down) to tune an antenna or something.

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