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TX Star 250 dx SWR ? (Something lost it's value ?)

Switch Kit

Switch Kit

Well-Known Member
Apr 6, 2005
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The amp has very good SWR's on low and medium power on both antenna and dummy load , the problem is when it's on the high side SWR is in the red ! both on dummy load and antenna ? It's weird because it's very good on the other settings ? Thanks . Switch
IMG_20220715_023752741[1].jpg
 

So what is this toggle switch with purple wires that is attached to the medium? Power switch supposed to do?

RF travels through those switches on the input side of the amp. Those wires are not conducive RF and will for sure throw the input tune of the amp off and if the input is thrown out of resonance, the output will be to.

Start with unsoldering those purple wires being careful not to drip solder down in the switch. They are a PITA to sort out once fouled up.
 
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Agreed. Someone added this delay so full power output can be obtained on SSB. I think in stock trim on SSB there are only two stages of power.
 
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Sorry I didn't explain myself better . The SWR bridge was after the amplifer and antenna and dummy load from there , and yes the switch was a mod to open the relays for full power on SSB and to switch off if I were to use AM without a slight delay there after which seemed to work well..........like I said SWR's are fine on medium and low , in the red on High ..........thought maybe the amp itself went out of tune but why would SWR be OK on all the other settings ? ........You may be right KC8mob ? but why not on the other settings ? .....if a kidney bean went bad , wouldn't the SWR go bad on all settings ? ...........There were two ways of doing the SSB mod for full power use on SSB ........... you could just jump pins 2&3 on the switch , I chose to use a toggle because they said you would get a slight delay when you unkeyed on AM after you did the mod .........I will certainly try your suggestion KC8 ..........Thank you all for your input on this . News at a 11 ! Switch
 
Well , disconnected Sideband mod completely , same SWR results on the High side Grrrrr ! even tried different sized coax jumpers and still the same ! Could it be a kidney bean in the tuning section ? but like I said , why would all the lower power settings work great ? I'm guessing this amps at least 20 years old .......What was Texas Star thinking only to be able to use this particular box half power on the sidebind side only to have major delay problems on the high ? Gets a little harder for me these days in the parts department , the last electronics store in my area closed down a few years back ........oh well , back to the drawing board. Thanks again guys and I always appreciate your know hows. Switch
 
Switch Kit said:
Sorry I didn't explain myself better . The SWR bridge was after the amplifer and antenna and dummy load from there , and yes the switch was a mod to open the relays for full power on SSB and to switch off if I were to use AM without a slight delay there after which seemed to work well..........like I said SWR's are fine on medium and low , in the red on High ..........thought maybe the amp itself went out of tune but why would SWR be OK on all the other settings ? ........You may be right KC8mob ? but why not on the other settings ? .....if a kidney bean went bad , wouldn't the SWR go bad on all settings ? ...........There were two ways of doing the SSB mod for full power use on SSB ........... you could just jump pins 2&3 on the switch , I chose to use a toggle because they said you would get a slight delay when you unkeyed on AM after you did the mod .........I will certainly try your suggestion KC8 ..........Thank you all for your input on this . News at a 11 ! Switch
Click to expand...
Only ONE SWR on ONE Antenna.No SWR's it's Singular not Plural.I have never ever seen an SWR's Meter just SWR Meters.

SIX-SHOOTER
W4KVW
WRMX520
 
Thank you for clearing that up for me on the SWR , now if I could just figure out how to fix my problem because it would be nice to use the high side of the amplifier. Thanks
 
You're not going to like the answer. Your amplifier is oscillating. That is a typical problem with smaller Texas Star amplifiers, due to their bias circuit design, sharing an RF contact on the relay.
 
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kc8mob said:
So what is this toggle switch with purple wires that is attached to the medium? Power switch supposed to do?

RF travels through those switches on the input side of the amp. Those wires are not conducive RF and will for sure throw the input tune of the amp off and if the input is thrown out of resonance, the output will be to.

Start with unsoldering those purple wires being careful not to drip solder down in the switch. They are a PITA to sort out once fouled up.
Click to expand...
Even with my new eyes I missed that one!
 
338_MtRushmore said:
I have a pretty long end fed, and it has many different swr's depending on the frequency. I can see how it could be annoying though.
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Do you understand what Standing Wave Ratio stands for? It's why they sell SWR Meters & Not SWR's meters.No such thing as Standing Wave Ratios. {:>)

SIX-SHOOTER
W4KVW
W4MX520
 
SIX-SHOOTER said:
Do you understand what Standing Wave Ratio stands for? It's why they sell SWR Meters & Not SWR's meters.No such thing as Standing Wave Ratios. {:>)

SIX-SHOOTER
W4KVW
W4MX520
Click to expand...
I'm just giving you a hard time, but now I am curious... If my swr meter reads 1.1 on 20 meters, and 1.4 on 40 meters... is my singular swr 1.25?
 

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