-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Texas Star DX500 and high SWR
- Thread starter 2RT307
- Start date
Oh really? So what did they care to mention to you what THEY thought it was? It is funny that they told you this as my conversation with them was totally different. But then again......
The fact that they kept the choke redesign to themselves knowing that the origonal parts go high in resistance and didn't decide to disclose it to me till the last minuite says something.
Changing out the sandbars and the chokes HAD a positive effect on the harmonic infiltration and thus the swr issues. Perhaps there are now issues arising with their "general" input tuning?
It will be interesting to see what they actually find and weather you see a difference that remains "fixed".. as the only two things left would be the 15pf coupling cap for the rf keying circuit and the 1000pf input coupling cap.
This will be interesting nevertheless. Keep us posted.
Oh, by the way. I would not be supprised if you find a 75 ohm resistor(pad) soldered on the input as was suggested to me. You will be able to tell this by a loss of power on the output.
The fact that they kept the choke redesign to themselves knowing that the origonal parts go high in resistance and didn't decide to disclose it to me till the last minuite says something.
Changing out the sandbars and the chokes HAD a positive effect on the harmonic infiltration and thus the swr issues. Perhaps there are now issues arising with their "general" input tuning?
It will be interesting to see what they actually find and weather you see a difference that remains "fixed".. as the only two things left would be the 15pf coupling cap for the rf keying circuit and the 1000pf input coupling cap.
This will be interesting nevertheless. Keep us posted.
Oh, by the way. I would not be supprised if you find a 75 ohm resistor(pad) soldered on the input as was suggested to me. You will be able to tell this by a loss of power on the output.
A Texas Star 500 is a much better choice then the 667 (built in driver). A 667 is very much a low low drive amp, 1-1.75 watt dead key and 20 watts peak er so max input is all it needs.
A 667 is a cranky amp that tends to run hot because most people over drive them. With the 500 you can run many different radio's into it because it can handle a wider range of inputs.
Everyone's agreeing about the 500 being the way to go. The only radios I have so far is the 959,CRE-8900,a TRC-428(bought new in 82')
Make sure that if anyone gets a TS 500 and plans to run an export on it, don't get a V model. High amounts of PEP wattage will burn out the variable pot. Get the 4 button version instead. I've had better than a dozen of the TS 500V's come across my bench in the last 6-8 months with burned out variable pots because the owners were running an export radio into them. 
~Cheers~
~Cheers~
Make sure that if anyone gets a TS 500 and plans to run an export on it, don't get a V model. High amounts of PEP wattage will burn out the variable pot. Get the 4 button version instead. I've had better than a dozen of the TS 500V's come across my bench in the last 6-8 months with burned out variable pots because the owners were running an export radio into them.
~Cheers~
Thank you! I was checking out the v models because I thought it offered me greater tunabilty. Where do you buy yours at?
https://www.gijoesradioelectronics.com/scripts/prodView.asp?idproduct=441
Last edited:
Make sure that if anyone gets a TS 500 and plans to run an export on it, don't get a V model. High amounts of PEP wattage will burn out the variable pot. Get the 4 button version instead. I've had better than a dozen of the TS 500V's come across my bench in the last 6-8 months with burned out variable pots because the owners were running an export radio into them.
~Cheers~
How much power are they running into it?
Running an export radio with a 500v with the variable fully clockwise will not burn out. In my experence this only happens when you use the variable to control your output. If you have a 500v don't panic thinking you will burn it out, if your export rig utilizes an rf power control use that to control your output by varying the input.
Now having said this if you are seeing NEWER models that this is happening to with the variable fully counter clockwise then it is a problem with the pot. I have heard rumors that they were going to change this component to something of the heavier duty veriety in a much lower ohm rating. If in fact these are the newer ones then this is a new issue with them.
These are of various models, from the older ones to the newer ones. While you are correct in saying that you will not burn out the pot with it fully clockwise, people want the variable to be able to adjust output. I usually find the pot burned out about halfway open. I can always tell where people run the TS-500V's by where the pot is burned out at!
High deadkey kills the pots right away (unless the pot is fully clockwise, wide open), high SSB output kills the pots in a few months with constant usage.
The variable is of poor design; they should use at LEAST a 5W variable. Not the 2W or 3W variable they use now. Would make for a far more durable amp when the variable is in use.
~Cheers~
High deadkey kills the pots right away (unless the pot is fully clockwise, wide open), high SSB output kills the pots in a few months with constant usage.
The variable is of poor design; they should use at LEAST a 5W variable. Not the 2W or 3W variable they use now. Would make for a far more durable amp when the variable is in use.
~Cheers~
Is it possible to replace the pot with a higher wattage part to make it a useable feature? If so, what specs should I look for in a suitable replacement? I'm passing my DX500 with a Galaxy 979, just tuned up by DTB.
supposedly that were going to do that with a higher wattage one, However I have heard that it was going to be of a much lower ohm rating that would reduce the adjustment range considerably.
The problem with the variable is you need a non inductive carbon type potentiometer for the circuit. I'm not aware of any company that manufactures one that handles over 1 watt today. Clarostat use to make some heavy duty ones decades ago but I don't think they are even around today. One option may be to gang a pair together on the same shaft and parallel their connections.
Perhaps they could discontinue these variable types knowing there is an issues with using them with modern rigs being that 90%of exports radios utilizes some sort of variable power control on them.
That's correct. And I have no idea why it hasen't been changed. Those that have these amplifiers can disconnect the potentiometer in lieu of a sandbar resistor if they cannot resist the urge to use it.