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RF Power knob on DaveMade 2X4

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RF Power knob on DaveMade 2X4

Post by Runaway » Tuesday, 11 April 2017, 18:38 PM

Can someone explain just exactly what all the power knob on the amp is for? I've always heard to run it wide open so that's what I've always done, but now I'm having a hard time getting my General Lee to set a low deadkey into the box. When I try to set it for about a 200 watt carrier (less than a watt DK on low) it just won't swing up, have to set it about 300 for it to ever DK. Isn't that a little too much for the driver in this amp? And I noticed it will go down when I turn the RF power knob on the amp. Any info would be a big help.

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Re: RF Power knob on DaveMade 2X4

Post by jessejamesdallas » Tuesday, 11 April 2017, 18:56 PM

General Lee is too much radio for a 2x4 for starters...

You can turn the variable on the amp down like you did, but your over driving the amp with that radio...That amp would be better suited for something like a Cobra 19 or Uniden 510 or 520xl...something with little swing.


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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Tuesday, 11 April 2017, 20:12 PM

jessejamesdallas wrote:
Tuesday, 11 April 2017, 18:56 PM
General Lee is too much radio for a 2x4 for starters...

You can turn the variable on the amp down like you did, but your over driving the amp with that radio...That amp would be better suited for something like a Cobra 19 or Uniden 510 or 520xl...something with little swing.
Been doing it for 10 years. I know you remember when Mike from radioactive was selling these General Lee's and practically everybody on this forum was promoting this 2x4 back in those days. What has changed after after all these years?

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Tuesday, 11 April 2017, 20:50 PM

You're not the only one I've seen say that though, Mr. Jessie..

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Re: RF Power knob on DaveMade 2X4

Post by Crusher » Wednesday, 12 April 2017, 1:32 AM

A 2x4 should only be ran with a single final radio. They worked great back in the day for like a Cobra 148GTL. They don't need nothing for drive. Even a Cobra 29 peaked doing 30w is too much.

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Re: RF Power knob on DaveMade 2X4

Post by Bozo » Wednesday, 12 April 2017, 2:23 AM

jessejamesdallas wrote:
Tuesday, 11 April 2017, 18:56 PM
General Lee is too much radio for a 2x4 for starters...

You can turn the variable on the amp down like you did, but your over driving the amp with that radio...That amp would be better suited for something like a Cobra 19 or Uniden 510 or 520xl...something with little swing.
I run a General Lee myself. How did this sound to you Jesse? Remember this?


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Re: RF Power knob on DaveMade 2X4

Post by sonoma » Wednesday, 12 April 2017, 2:58 AM

that setup should work with a 2 watt feed into the amp. how much does the radio swing to with out the amp hooked up from a 2 watt dead key. the radio may not be swinging much depends on how it is set up. if it only swings to about 20 watts with a good loud audio into the mic it should work fine. is the amp a new or old unit. it may have a problem. put the amp on high when you try it with the radio. do not remember just how much the dave amps put out with a 2x4 but you want about 1/4 of what the amp should do . if it is rated for 600 watts you would only want about a 150 watt out put with just a dead key.

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Wednesday, 12 April 2017, 3:08 AM

Crusher wrote:
Wednesday, 12 April 2017, 1:32 AM
A 2x4 should only be ran with a single final radio. They worked great back in the day for like a Cobra 148GTL. They don't need nothing for drive. Even a Cobra 29 peaked doing 30w is too much.

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I have a General A.P Hill. Remember those radios? It's a single final radio, but strong radio. Would it be good to run the 2x4 with? It swings close to 30watts itself.

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Re: RF Power knob on DaveMade 2X4

Post by jessejamesdallas » Wednesday, 12 April 2017, 3:34 AM

Bozo wrote:
Wednesday, 12 April 2017, 2:23 AM
jessejamesdallas wrote:
Tuesday, 11 April 2017, 18:56 PM
General Lee is too much radio for a 2x4 for starters...

You can turn the variable on the amp down like you did, but your over driving the amp with that radio...That amp would be better suited for something like a Cobra 19 or Uniden 510 or 520xl...something with little swing.
I run a General Lee myself. How did this sound to you Jesse? Remember this?
Didn't say "it wont work", Just allot of drive for a 2x4...


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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Wednesday, 12 April 2017, 11:30 AM

sonoma wrote:
Wednesday, 12 April 2017, 2:58 AM
that setup should work with a 2 watt feed into the amp. how much does the radio swing to with out the amp hooked up from a 2 watt dead key. the radio may not be swinging much depends on how it is set up. if it only swings to about 20 watts with a good loud audio into the mic it should work fine. is the amp a new or old unit. it may have a problem. put the amp on high when you try it with the radio. do not remember just how much the dave amps put out with a 2x4 but you want about 1/4 of what the amp should do . if it is rated for 600 watts you would only want about a 150 watt out put with just a dead key.

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I have about 24-25 watt swing into the box. With less than a watt DK into the box it deadkeys about 300 watts. That's the lowest I can get it or it doesn't DK at all.

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Re: RF Power knob on DaveMade 2X4

Post by sonoma » Wednesday, 12 April 2017, 14:04 PM

how does it do with other radios? I do not have a good answer for you as to how Dave made did this amp.

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Re: RF Power knob on DaveMade 2X4

Post by Crusher » Wednesday, 12 April 2017, 14:12 PM

The input to driver stage needs modified. Too much stage gain. If the resistor values are changed to something else. It will work fine.

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Wednesday, 12 April 2017, 15:33 PM

sonoma wrote:
Wednesday, 12 April 2017, 14:04 PM
how does it do with other radios? I do not have a good answer for you as to how Dave made did this amp.

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I know this is going to sound crazy, but it only changes when I change coax. I have some cheap truck stop coax that runs high SWR and it does good, can set the DK as low as I want, but put it on some good Belden RG8X that I just made with Amphenol pl259s with perfect SWR and this is what I get. Go figure.

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Wednesday, 12 April 2017, 15:39 PM

Crusher wrote:
Wednesday, 12 April 2017, 14:12 PM
The input to driver stage needs modified. Too much stage gain. If the resistor values are changed to something else. It will work fine.

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Greek to me.. Wish I just had a straight Toshiba 4 pill and be done with it and not have to worry and babysit.

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Re: RF Power knob on DaveMade 2X4

Post by Crusher » Wednesday, 12 April 2017, 15:57 PM

If that's the case, just disconnect driver. Move coax from Pot to input of 4 pill. Disconnect 2 pill output going to input of 4 pill. I also disconnect the positive lead going to 2pill section. Easy.

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Re: RF Power knob on DaveMade 2X4

Post by jessejamesdallas » Wednesday, 12 April 2017, 16:06 PM

Or you could put a switch on it so you could turn off the driver stage...


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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Wednesday, 12 April 2017, 16:44 PM

Crusher wrote:
Wednesday, 12 April 2017, 15:57 PM
If that's the case, just disconnect driver. Move coax from Pot to input of 4 pill. Disconnect 2 pill output going to input of 4 pill. I also disconnect the positive lead going to 2pill section. Easy.

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I really like the sound of that. But not really that savy on what you are saying. Are you saying it's really easy? Could you maybe walk me through it?

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Wednesday, 12 April 2017, 16:45 PM

jessejamesdallas wrote:
Wednesday, 12 April 2017, 16:06 PM
Or you could put a switch on it so you could turn off the driver stage...
I like the sound of this even more! But sounds more complicated than just disconnecting the driver stage. But would really like to look into it.

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Re: RF Power knob on DaveMade 2X4

Post by Bozo » Wednesday, 12 April 2017, 21:09 PM

jessejamesdallas wrote:
Wednesday, 12 April 2017, 3:34 AM
Bozo wrote:
Wednesday, 12 April 2017, 2:23 AM
jessejamesdallas wrote:
Tuesday, 11 April 2017, 18:56 PM
General Lee is too much radio for a 2x4 for starters...

You can turn the variable on the amp down like you did, but your over driving the amp with that radio...That amp would be better suited for something like a Cobra 19 or Uniden 510 or 520xl...something with little swing.
I run a General Lee myself. How did this sound to you Jesse? Remember this?
Didn't say "it wont work", Just allot of drive for a 2x4...
Too funny. HO HO HO!

I REMEMBER THAT JESSE

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Re: RF Power knob on DaveMade 2X4

Post by sonoma » Thursday, 13 April 2017, 1:23 AM

after thinking about your problem I wonder if you have some resisters that are going bad from driving them too hard at times. look and see if any are off colored or burnt looking. I have a texas star 5009hdv that at one time the variable was going bad and if it was on low it would work as it should. as soon as I turned it up say 1/2 way it would jump to full out put. after I put a new variable control in it the amp went back to working as it should. I think some one earlier on mentioned possible bad caps ot resisters going bad. if you know how to test it might be worth the try.some where I have a old procedure that a texas star tech had a web site and posted it. only problem Bozo does not let me post it to the web site since the guy is no longer around and not a sponsor.
I had heard he passed away a couple years ago and is site went down shortly after that.

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Thursday, 13 April 2017, 11:30 AM




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Re: RF Power knob on DaveMade 2X4

Post by Crusher » Thursday, 13 April 2017, 16:13 PM

Ugh! Sheet metal screws for SO239's? I hate when they do that.

As to the 2 resistors on pot. Their is 2 of the 47ohm is parallel. I usually do a single 47ohm 3 or 5w metal oxide. This will slow down the drive going into driver. You may be able to carefully cut lead on just one and see if it behaves better. When I built a few of those years back, I did 50 ohms to ground and 50 ohms to input. Or 47 ohm to each. Bleeds off more drive and amp doesn't take off.

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Thursday, 13 April 2017, 16:37 PM

Crusher wrote:
Thursday, 13 April 2017, 16:13 PM
Ugh! Sheet metal screws for SO239's? I hate when they do that.

As to the 2 resistors on pot. Their is 2 of the 47ohm is parallel. I usually do a single 47ohm 3 or 5w metal oxide. This will slow down the drive going into driver. You may be able to carefully cut lead on just one and see if it behaves better. When I built a few of those years back, I did 50 ohms to ground and 50 ohms to input. Or 47 ohm to each. Bleeds off more drive and amp doesn't take off.

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You mean where I put the blue line in the picture?

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Re: RF Power knob on DaveMade 2X4

Post by Crusher » Thursday, 13 April 2017, 17:24 PM

Yes,carefully cut so if u need to, you can solder back

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Re: RF Power knob on DaveMade 2X4

Post by Crusher » Thursday, 13 April 2017, 21:18 PM

Did you try!

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Thursday, 13 April 2017, 22:08 PM

Crusher wrote:
Thursday, 13 April 2017, 21:18 PM
Did you try!

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Working right now. Will try tomorrow. Thank you!

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Friday, 14 April 2017, 10:36 AM

Crusher wrote:
Thursday, 13 April 2017, 21:18 PM
Did you try!

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Didn't really change anything..
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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Friday, 14 April 2017, 10:44 AM

Does the RF PWR knob on the box change the wattage into the driver? When I set the low power of the radio (VR16) TO DK into the box it's so low that it either won't DK, or it pops about 300 watts into the box. But when I turn the variable knob down I can lower it to about 220-250. Is that even really working?

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Re: RF Power knob on DaveMade 2X4

Post by Crusher » Friday, 14 April 2017, 14:52 PM

Too much radio for that amp. I'll try to message you tomorrow see if I can help you convert to just a 4 pill. Been on the roof last 2 days all day working on ACunits. I'm beat

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Re: RF Power knob on DaveMade 2X4

Post by Runaway » Friday, 14 April 2017, 15:38 PM

Crusher wrote:
Friday, 14 April 2017, 14:52 PM
Too much radio for that amp. I'll try to message you tomorrow see if I can help you convert to just a 4 pill. Been on the roof last 2 days all day working on ACunits. I'm beat

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Great.thanks

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Re: RF Power knob on DaveMade 2X4

Post by Bozo » Saturday, 15 April 2017, 9:14 AM

Runaway wrote:
Friday, 14 April 2017, 10:36 AM
Crusher wrote:
Thursday, 13 April 2017, 21:18 PM
Did you try!

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Didn't really change anything..
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