Galaxy dx949 SSB SWR ?

[BammBamm]

O.K. let me explain I tuned the SWR on my DX949 on AM channels 1 and 40 and have a 1.1 on both ends and AM works great ....BUT when I go to SSB my SWR light comes on when I key and SWR shows 3 but drops as I modulate to flat nothing? If I whistle in mic on SSB the SWR stay flat but the second I stop modulation it shoots back to 3 and the SWR light comes back on. I was told you can't read SWR on SSB and I understand this but why is my warning light coming on now and is this going to damage my radio? I know the 949 is known for SWR light issues should I get this into a shop ASAP? My external meter is showing the same results also but if I hook up my other radio it doesn't do this it shows no SWR on SSB until modulated then goes to about 1.2. I'm bald so I have no hair to pull out while worrying about this!

 

[loosecannon]

you are right that you cant really read your SWR in SSB mode, but your issue does seem a bit strange.

logically, in SSB mode, there is 0 watts out until you speak into the mic, and therefore, when you key your mic on SSB with no modulation, you should see 0 watts reflected back at the radio right?

the fact that your external SWR meter agrees with the internal meter in the radio certainly points to a problem somewhere, but im not completely certain yet that you actually have a problem that would hurt your radio.

try this, just so that everyone who reads this will be on the same page:
(i realize that you've basically already done most of this)

set your radio to either USB or LSB, doesnt matter which.
turn the mic gain all the way down.

hook up your external meter, set it to the CAL position, and turn the CALIBRATE knob all the way to the right. (all the way up)

now key the mic and note the reading on the external meter.
you should not see the needle move at all aside from a tiny bump and return when you first key the mic.

with the way you have the meter set, it is as sensitive as it gets to the power output of the radio.

if you get needle movement here, with a "SSB deadkey", then you are generating a carrier in SSB mode, and need to make an internal adjustment.
its easy and you can do it yourself.

what does your external meter read as far as WATTS out with your "SSB deadkey"?

what does it read with a fully modulated SSB signal?

LC

 

[BammBamm]

OK with external meter on CAL and mic gain turned down the meter still goes to 3 . This is very confusing. I am getting great reports from everyone though? Like I said the SWR is perfect on AM and only does this on SSB but I mainly use 38LSB. I think I'm going to take it to my local shop. But if it is in the antenna I'm Kind of screwed due to it being a base. The coax is LMR-400 and it checks good with ohm meter. It does this with both antennas I have here a Protron P-99 and a sirio s-2016. I disconnected my antenna switch box and went straight from radio to each antenna with same results.

 

[BammBamm]

OK I tried adjusting the SSB carrier and it made no difference. But I also found that if the swr meter on radio is set to pwr when I dead ket in ssb mode it goes to about 6 and swings off the scale when modulated with the mic gain off it sits at 6 when keyed. I'm going to take it in when I can and will post the findings but until then I will be using my other radio. It may be a couple weeks until I get paid and can get a day to go to the shop. I hate bi-weekly paydays

 

[BammBamm]

By the way the external meter is showing 5-6 watts on dead key and swings to about 30 when modulated.

 

[unit248]

You said:

"with external meter on CAL and mic gain turned down the meter still goes to 3."

With a properly functioning radio set to SSB (either USB or LSB), you should never have any RF output (or at least none that you can easily measure) until there's audio at the mic. That means with the mic gain all the way down, there should be 0 watts out, and neither your wattmeter or SWR meter should ever show any deflection (either in CALibrate mode or SWR mode).

So if you are seeing RF out of the radio in SSB mode (and you're sure your mic gain control isn't broken), then I'd say there's something wrong with your radio.

Is this behavior new? That is, did the radio work ok on SSB before and only recently started doing this, or has it been like this all along?

Did you by any chance have the radio "peaked and tuned?" If so, then it's possible that whatever was done improved AM but broke SSB. I vaguely remember reading that some forms of negative peak compression (NPC) mods designed to provide increased modulation on AM can actually be detrimental to SSB operation. It could also be that someone turned the wrong trimmer pot inside the radio by mistake.

-Bill

 

[loosecannon]

when i asked for the wattage readings, i meant in SSB mode, so im assuming that the 5-6 watt deadkey and 30 watts of modulation are in SSB mode.

is that the case or did you give me the wattage readings for AM mode?

if it was in SSB that you measured a 5-6 watt carrier, then you definitely have a problem with the radio.

the only thing i cant figure out is how you are getting good signal reports on SSB when you are generating a carrier.
those who hear you should be telling you that they are hearing a heterodyne (tone) with your audio.

are you sure you are getting good signal reports on SSB?

make sure that VR13 isnt maxed out. it should be set for no more than 20 watts PEP on SSB. if its the MOSFET version, you can go for 25 watts, but no one will notice the difference.

also make sure VR17 isnt maxed out.

VR6 is the SSB carrier balance control, and the way to adjust it is to set your radio to either USB or LSB mode and turn the mic gain all the way down.
key the mic and adjust VR6 for minimum needle movement.
it really shouldnt move at all when you key the mic.

if none of this gets you anywhere, its time to send it to a good shop, as there is something strange going on inside that radio.

good luck,
LC

 

[BammBamm]

I have disconnected this radio and put it on a shelf and yes all readings where in SSB. I will get it in by the end of this month and see what is going on. It worked fine and I still get great reports from the locals but became afraid of destroying it so it got put up. Sure is quite in the mobile without it as it is the only radio in the mobile. I guess I could sing to myself Money is a little tight right now so I have to wait for a while. This radio is from Sparky's and was a refurb. I got it shortly after Christmas and they did the peak and tune along with unlock the clarifier before I got it. It worked great and still seems to but we will find out. Just so nobody gets any ideas by no means am I blaming Sparky's and I would send it back to him but by the time I pay shipping and wait for it I can take it to my local shop who also has a lifetime warranty and they will tell me what they find. I would buy another from sparky in a heartbeat but I am hoping I don't have to.