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

Switch Kit

Active Member
Apr 6, 2005
3,580
99
48
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
 

kc8mob

Active Member
Sep 26, 2017
89
90
48
40
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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9C1Driver

Sr. Member
Aug 13, 2008
3,724
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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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Switch Kit

Active Member
Apr 6, 2005
3,580
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48
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
 

Switch Kit

Active Member
Apr 6, 2005
3,580
99
48
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
 

SIX-SHOOTER

Sr. Member
Oct 2, 2010
1,050
1,373
173
Macclenny,Fla.
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
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
 

Switch Kit

Active Member
Apr 6, 2005
3,580
99
48
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
 

Shockwave

Sr. Member
Sep 19, 2009
3,785
3,286
273
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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Woody-202

Sr. Member
Sep 5, 2018
587
947
103
66
www.cbdaze.blogspot.com
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.
Even with my new eyes I missed that one!
 

338_MtRushmore

Sr. Member
Jun 17, 2012
1,639
1,141
193
The Dakotas
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
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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