So it goes in line between the radio and the amp instead of between the amp and the antenna? Maybe that's my confusion...
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Need Amp Recommendation
- Thread starter Brian G
- Start date
Brian G,
You don’t need a 750 watt capable tuner. As Brad mentioned, the tuner will go between your Stryker and the amplifier. You would then tune the “Antenna Tuner” so that your Stryker “sees” a low SWR. 100 watts should do the trick.
Another option would be to remove the first driver tube in your Pal 750 and drive the “2nd Stage” ( 2-8950’s) directly with the radio. It would require a coil and trimmer capacitor to the “new” 2 tube input stage but would allow a larger drive input. Since you already have the amplifier (and good tubes in it) this would not be a difficult modification or cost near as much as a Texas Star DX500 and a couple of power supplies.
Food for thought.
73
David
You don’t need a 750 watt capable tuner. As Brad mentioned, the tuner will go between your Stryker and the amplifier. You would then tune the “Antenna Tuner” so that your Stryker “sees” a low SWR. 100 watts should do the trick.
Another option would be to remove the first driver tube in your Pal 750 and drive the “2nd Stage” ( 2-8950’s) directly with the radio. It would require a coil and trimmer capacitor to the “new” 2 tube input stage but would allow a larger drive input. Since you already have the amplifier (and good tubes in it) this would not be a difficult modification or cost near as much as a Texas Star DX500 and a couple of power supplies.
Food for thought.
73
David
Hi Dave. I would do that but honestly I would need to have step by step and parts list. I’m not as knowledgeable to figure all that out the way you all are. ;( I’m pretty good at actually doing the work but not designing it. If that makes sense.
Brian G,
It is not that difficult to add the input tune set up. You would be interrupting the coax feed from the relay to the first driver tube and install a coil of wire between the two points. The coil of wire will be about 1/2” diameter and 6-8 turns long-but the “cut and try” method should be employed for the best result. At on end of the coil you will install a trimmer capacitor to ground. Again the cut and try method to get the best input match should be used.
If you opt to bypass the single driven tube for the 2 tube option, the coax from the relay to the single tube would be removed from the single tube and moved to the location where the single tube feeds the next driven tube section.
It sounds like a lot of work but could be done in an hour or two.
73
David
It is not that difficult to add the input tune set up. You would be interrupting the coax feed from the relay to the first driver tube and install a coil of wire between the two points. The coil of wire will be about 1/2” diameter and 6-8 turns long-but the “cut and try” method should be employed for the best result. At on end of the coil you will install a trimmer capacitor to ground. Again the cut and try method to get the best input match should be used.
If you opt to bypass the single driven tube for the 2 tube option, the coax from the relay to the single tube would be removed from the single tube and moved to the location where the single tube feeds the next driven tube section.
It sounds like a lot of work but could be done in an hour or two.
73
David
what size wire would I use and what size trimmer cap to start with? Doesn't sound to bad otherwise
And this should eliminate the SWR issue if done correctly in addition to allowing a higher drive?
Brian G,
If you add the input tune control to the amplifier as it is, it will allow you tune the input section of the amplifier to a better match to your Stryker. Not unreasonable to expect less than 1.5:1.
If you eliminate the first driven tube and drive the next section (2-8950's) and add a tuning coil* to that section, it will allow a larger drive (since now you would be driving 2-8950's instead of 1-8950) and allow a tunable input to that 2 tube section. It may or may not take the full output power from your Stryker but should make the amplifier less prone to gain issues.
(*The amplifier may include a tunable Pi network for the 2 tube section. I will look at the schematic and see)
A simple tuned input circuit below. The black coax goes too the driver tube (8950 in this case) cathode, the tan coax comes from the relay. There is a $5.00 trimmer capacitor and about 6 inches of 14ga solid wire and 2 wire terminals added.
73
David
If you add the input tune control to the amplifier as it is, it will allow you tune the input section of the amplifier to a better match to your Stryker. Not unreasonable to expect less than 1.5:1.
If you eliminate the first driven tube and drive the next section (2-8950's) and add a tuning coil* to that section, it will allow a larger drive (since now you would be driving 2-8950's instead of 1-8950) and allow a tunable input to that 2 tube section. It may or may not take the full output power from your Stryker but should make the amplifier less prone to gain issues.
(*The amplifier may include a tunable Pi network for the 2 tube section. I will look at the schematic and see)
A simple tuned input circuit below. The black coax goes too the driver tube (8950 in this case) cathode, the tan coax comes from the relay. There is a $5.00 trimmer capacitor and about 6 inches of 14ga solid wire and 2 wire terminals added.
73
David
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Davids solution is valid…I see your eyes lighting up when you say “in addition to allowing a higher drive.” I wouldn’t be thinking more output by doing this. By eliminating the one driver tube you’ll have to increase you input wattage to see the same 750 you’re getting now? David’s solution is simply a way to work around having to use a low drive because you’re eliminating a driver tube. You’re still left with the high SWR issue and therefore the addition of a coil and trimmer capacitor is to match your radio (which is showing high SWR) to the input of the amplifier.
My take is simply this, you amplifier was working just fine prior to changing radios. In fact your amplifier is still working fine it’s the radio that’s not working fine. Put a tuner between your new radio and amplifier and you’ll be back to where you were…happy as a lark everything is working.
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No I realize I won’t get any more out of it and I wouldn’t try. Amp wasn’t designed to do more then what it is. Just trying to figure out now which to try. I’d have to know the suggested wire and cap specs he referenced but I might be willing to try that to save some more money.
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Above post edited to include a picture from the Palomar Skipper I did for a friend a few years ago. You can almost make out the part number on the trimmer capacitor. Looks like "303" I wouldn't swear this is an Arco trimmer but they are available.
Above post edited to include a picture from the Palomar Skipper I did for a friend a few years ago. You can almost make out the part number on the trimmer capacitor. Looks like "303" I wouldn't swear this is an Arco trimmer but they are available.