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In your opinion....
- Thread starter radioman24
- Start date
I would guess no difference short the variable, mainly because the non-variable 667 is like running the 667v wide open on the variable.
They are both 1x4s, just one has the ability to "turn down" the input from the radio.
Hey Dan, Yeah, especially with an amp that big, you want the variable capability.
I don't mean to dredge up the "swing or not to swing" war of morons again but it should be noted:
Several locals around me have the 667''s. Yes, you certainly can put 4 or 5 watts into them and the amp will dead key around 500 watts and then swing forward with modulation to it's full output, which they say is anywhere from 650 to 800 watts. {high amp dead key with short swing to full output}
BUT, like this, with the high dead key of 500 watts on the amp, the modulation sounds tight and pinched up, kind of distorted.
But if you only imput around 1 & 1/2 or 2 watts dead key from the radio, and you turn the variable down to around 100 or 150 watts or so dead key from the amp, the amp will easily swing forward to it's full output with modulation and will be loud and clean and clear. {much lower dead key from amp with much greater swing range to full output}
Everybody gives the exact same over the air audio reports. High dead key on these pill boxes produces pinched-up distorted modulation. Much lower dead key with full pep swing gives loud - clean - clear audio.
Anyone who says otherwise has been reading too many books and doesn't have any or enough over-the-air experience with these devices.
Good luck!
I don't mean to dredge up the "swing or not to swing" war of morons again but it should be noted:
Several locals around me have the 667''s. Yes, you certainly can put 4 or 5 watts into them and the amp will dead key around 500 watts and then swing forward with modulation to it's full output, which they say is anywhere from 650 to 800 watts. {high amp dead key with short swing to full output}
BUT, like this, with the high dead key of 500 watts on the amp, the modulation sounds tight and pinched up, kind of distorted.
But if you only imput around 1 & 1/2 or 2 watts dead key from the radio, and you turn the variable down to around 100 or 150 watts or so dead key from the amp, the amp will easily swing forward to it's full output with modulation and will be loud and clean and clear. {much lower dead key from amp with much greater swing range to full output}
Everybody gives the exact same over the air audio reports. High dead key on these pill boxes produces pinched-up distorted modulation. Much lower dead key with full pep swing gives loud - clean - clear audio.
Anyone who says otherwise has been reading too many books and doesn't have any or enough over-the-air experience with these devices.
Good luck!
the variable on the amp would be for output from the amp not input from the radio. You can't adjust the dead key or output of the radio from a control on the amplifier.
Wrong on that one dude. The output FROM the radio itself stays the same however the variable changes the drive level FROM THE RADIO going INTO THE AMP and therefore since the drive level changes the output from the amp changes. All the variable is is a simple pot.
Do the variables seem to hold up doing that?
I thought I remembered this being a problem on some amps, the variable burns itself out because it isn't properly sized for the (typical export) radio's output and it gets overloaded.
I have been told by more than one person to run the variable WFO and control the input at the radio...and I always wondered why install a variable in the first place??
Seeing that the input of the radio goes through the variable pot in the amp I would venture to say, no I know that your statement is one of a person who has no clue as to the circuitry of an amplifier.
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i was only talking about the radio itself. I understand that the amplifier attenuates the input signal from the radio which accomplishes the same thing and maybe I misread the post, but I posted what I did because of some guy reading that and saying "I don't need to adjust my dead key, i can just do it with this little knob"
and there are lots and lots of things I don't know and I'm the first one to admit it. that's why I'm here learning
and there are lots and lots of things I don't know and I'm the first one to admit it. that's why I'm here learning
Its my understanding that the variable on the amp does just that, puts some of the radio's input to ground and thereby attenuates the [radio's] input power to the amp.
Instead of having the variable in the radio, its in the amp. Which, by my understanding, is NOT ideal.
Okay, so if you can get full output of the amp on a low variable setting, is your impedence going to change? Aside from the problems related to the switch itself, is this an acceptable way to run a radio/amp setup? I was under the impression that you had to set up the radio to drive the amp not the other way around.
i was only talking about the radio itself. I understand that the amplifier attenuates the input signal from the radio which accomplishes the same thing and maybe I misread the post, but I posted what I did because of some guy reading that and saying "I don't need to adjust my dead key, i can just do it with this little knob"
and there are lots and lots of things I don't know and I'm the first one to admit it. that's why I'm here learning
Well the radios variable does control the radios output but the amps variable controls the radios output into the amp so if you had an amp with a variable pot then your first post would hold true about the radio.
Your best bet is if you have an amp with a variable pot would be to turn the amps variable pot full clockwise and control the amps output with the radios variable pot output.
I think the variable in the amp is a compromise, so that the buyer wouldn't need radio modifications to run said amp.
I prefer to have the deadkey/swing set in the radio for the amp, mainly because knobs can be bumped.
I heard (not sure if its true or not, one of those internet things) that one big amp manufacturer quit installing variables because they were getting burned up by guys trying to tame a power level that exceeded the variable's handling capacity.
the pots used in those variables are only good for several watts at the most and a lot do in fact get burned up. A lot of guys try and run the radio flat out and expect the variable to handle it and they just won't. If the radio has it power turned down, either by doing it internally on a fixed level basis or by using the RF Power control on the front panel, then the poat should be able to handle the few watts from the radio.
In reference to the question about whether the variable will change the driving impedance of the amp; YES as the variable is changed the input impedance and thus the SWR going into the amp will change somewhat. Just how much depends on the basic construction of the amp and value of components used.
In reference to the question about whether the variable will change the driving impedance of the amp; YES as the variable is changed the input impedance and thus the SWR going into the amp will change somewhat. Just how much depends on the basic construction of the amp and value of components used.