I see what you are saying I will check bias of driver and final what should they be set at same as all the others
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Ranger 69ffb4
- Thread starter my2995dx
- Start date
Remember too, your output strip only handles so many watts at any range of power.
IF you got reflections from parts of the strip producing more wattage than the others, that harmonic starts it trek down the strip to the amp - which is set up like a low- pass filter
Now think about this...
The Low-pass filter that should cut-down - still takes in the harmonics ABOVE a set range - it's not nil - it's still there - that amp will still amplify the frequencies due to the wideband range of frequencies it can amplify - it's not truly filtered or even designed to be filtered - it's in an amp. The higher gain of the amp still will develop the power at the higher frequencies too.
What is happening is the low-end range of what the radio produces, is mixing products that form the harmonics above - they are summed - that is going directly to the amplifier in the radio itself.
It's output even with that trap you put on the line - the reflections of the antenna are not able to radiate (well it is but not what you really want - count it all as wasted) is not the condition the system is in, You've proven that. But the output condition of the amplifier is not only producing 27MHz - but well above that too. This affects the SWR because of the power within the radio itself has frequencies the system is not tuned for - so that shows up as those reflections.
Why not all the range? Well, they are there - as an matter of efficiency, only the low-pass attenuation begins closer to 40MHz to handle that 2nd order - not at 27MHz where the main frequencies are produced and tuned for, You're just not seeing the attenuation of those frequencies past (below) a frequency the radios band-trap is set for - so you see "ghosting" of reflected power on the lower end because the harmonics produced are not as sharply attenuated below 52MHz (2nd order) so the higher end harmonics are not causing as much damage as the lower end - which also can contain the radios own main base oscillator frequency (10.240MHz as an example) spiking in there - being the main one back at the mixer in the TX strip - so the whole thing needs a good going over to reset the band pass the strip should amplify not overamplify at one section of the band pass to compensate for a non-equalized response - you'll have to find the culprit - and usually is a cap that either went off tolerance or needs to be resoldered. Let's hope it not that, and just needs a good re-tweaking of coils to re-center the peaking it needs to get the amp to see what it should amplify - not what it can amplify.
Did I mention Bias? Please set them on the conservative side - the amp, the power supply and all the others in the neighborhood - will thank you.
IF you got reflections from parts of the strip producing more wattage than the others, that harmonic starts it trek down the strip to the amp - which is set up like a low- pass filter
Now think about this...
The Low-pass filter that should cut-down - still takes in the harmonics ABOVE a set range - it's not nil - it's still there - that amp will still amplify the frequencies due to the wideband range of frequencies it can amplify - it's not truly filtered or even designed to be filtered - it's in an amp. The higher gain of the amp still will develop the power at the higher frequencies too.
What is happening is the low-end range of what the radio produces, is mixing products that form the harmonics above - they are summed - that is going directly to the amplifier in the radio itself.
It's output even with that trap you put on the line - the reflections of the antenna are not able to radiate (well it is but not what you really want - count it all as wasted) is not the condition the system is in, You've proven that. But the output condition of the amplifier is not only producing 27MHz - but well above that too. This affects the SWR because of the power within the radio itself has frequencies the system is not tuned for - so that shows up as those reflections.
Why not all the range? Well, they are there - as an matter of efficiency, only the low-pass attenuation begins closer to 40MHz to handle that 2nd order - not at 27MHz where the main frequencies are produced and tuned for, You're just not seeing the attenuation of those frequencies past (below) a frequency the radios band-trap is set for - so you see "ghosting" of reflected power on the lower end because the harmonics produced are not as sharply attenuated below 52MHz (2nd order) so the higher end harmonics are not causing as much damage as the lower end - which also can contain the radios own main base oscillator frequency (10.240MHz as an example) spiking in there - being the main one back at the mixer in the TX strip - so the whole thing needs a good going over to reset the band pass the strip should amplify not overamplify at one section of the band pass to compensate for a non-equalized response - you'll have to find the culprit - and usually is a cap that either went off tolerance or needs to be resoldered. Let's hope it not that, and just needs a good re-tweaking of coils to re-center the peaking it needs to get the amp to see what it should amplify - not what it can amplify.
Did I mention Bias? Please set them on the conservative side - the amp, the power supply and all the others in the neighborhood - will thank you.
I unhooked everything started over just to see here just with the 69ffb going into a meter and antenna swr 2 now hooked up this low pass filter it shot up to over 3 so going to check bias see where that's at and set it if needed then check again and if the same going to be looking at the meter it's a older one dee 2000 have a new cn-801 coming.
First thing hooked dummy load to the low pass filter hooked my analyzer to the other end swr shot up to 6 I think that filter is bad
Filter in line and had a bad jumper works fine now my question WTF are these transistors are in these some weird crap DE 26 never seen or heard of them thinking of getting them changed out to 2879 but don't know what that would costSomething like this would probably do the trick:
RM ITALY Low Pass Filter 27/586 (500 Watts, 3-30Mhz)
RM ITALY Low Pass Filter 27/586 (500 Watts, 3-30Mhz)88radio.com
Did you take some pictures? You've got to show us this DE26 you speak of!
Glad you got it back up and running.
My mistake RT28
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I have not heard of those before, but if it's working, I would run it. Someday if it has a problem, then replace them with HG 2879. They are probably not a direct swap, and the input and output transformer tuning would have to be changed.
Wow that's interesting! Wonder if that's what they're now using in all the 4 pill amp sections to replace the blacked out pills they'd been using.
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