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View Full Version : Is this a low or hi drive amp?



stealth
03-01-2013, 07:15 AM
I picked up a no name amp (looks like a Boomer/Palomar though) with four SD1446 pills in it. Wondering if this would be considered low or high drive? How many watts from the radio should these be fed for longevity?

94ct
03-01-2013, 07:20 AM
pictures help but 4 watts tops i bet

Beavis
03-01-2013, 08:48 AM
A 4 pill amp is a high drive amp. Like 94CT said, a 4 watt deadkey would be about the most I would put into it & let it swing from there. Below is the datasheet for the SD1446 pill, you can judge for yourself.
http://www.bellscb.com/products/Parts/images/SD1446.pdf

543
03-01-2013, 08:56 AM
Why is everyone always concerned with how many watts to put into an amp and not what's coming out the other end?

Big Nasty
03-01-2013, 08:59 AM
Why is everyone always concerned with how many watts to put into an amp and not what's coming out the other end?
Because putting too many watts into an amp can get expensive.

skidrow
03-01-2013, 09:23 AM
drive it with say 50 watts and see how ya sound....

king cobra
03-01-2013, 10:01 AM
Why is everyone always concerned with how many watts to put into an amp and not what's coming out the other end?

YOU CAN'T BE THAT DUMB!


Sent from my RDX iPhone

543
03-01-2013, 02:49 PM
Because putting too many watts into an amp can get expensive.

Blindly running an amp without knowing what its doing can get expensive too. Just because it has certain transistors doesn't mean it needs x amount of drive. The circuit design and biasing make a big difference. If you drive a 4 pill TX star like you would cruise a 4 pill comp box the deadkey out of the TX star will be way high.

king cobra
03-01-2013, 03:04 PM
Blindly running an amp without knowing what its doing can get expensive too. Just because it has certain transistors doesn't mean it needs x amount of drive. The circuit design and biasing make a big difference. If you drive a 4 pill TX star like you would cruise a 4 pill comp box the deadkey out of the TX star will be way high.

Uuummmmmm. And what controls the dead key coming out of the box?



I will answer my own question since you seam to have NO FUCKING CLUE. The dead key coming from the radio into the amp is what controls the dead key out of the amp.


Sent from my RDX iPhone

king cobra
03-01-2013, 03:08 PM
Just because it has certain transistors doesn't mean it needs x amount of drive.

That is where your wrong. The transistors in that box need less to drive it than just for say a 2890


Sent from my RDX iPhone

stealth
03-01-2013, 10:27 PM
I have pics f the amp but they're on my phone and I've yet to figure how to get them on here, albeit me having a smart phone. Perhaps there's an app I need to do this....?

94ct
03-01-2013, 10:33 PM
upload to free picture host tiny pic or photo bucket you can tether you phone to comp to upload load pictures or can pay for talptalk

543
03-01-2013, 10:42 PM
Uuummmmmm. And what controls the dead key coming out of the box?



I will answer my own question since you seam to have NO FUCKING CLUE. The dead key coming from the radio into the amp is what controls the dead key out of the amp.


Sent from my RDX iPhone

Very good. And how those little parts between the in and out connectors make a difference too. Take a 4 pill (2879 not 2890s or whatever you're talking about)... deadkey 5 watts into the Texas star and see what deadkey comes out of the amp. Write that down and then throw the davemade inline. Deadkey that same 4 watts into it and see what comes out.

They have the same pills, both are 4 pill amps but for some strange reason the davemade doesn't deadkey as much as the 500. Then take the Texas star and disconnect the bias supply and ground the base of the pills so its a class c amp....now it deadkeys less with the same amount of input.

Did we just misunderstand one another or do you want to explain why I'm wrong?

Crusher
03-01-2013, 10:51 PM
Don't forget the wraps on the transformers also affects what drive is needed. The DM style has 3 wraps. While other amps will have 4 some even have 5 wraps. With more wraps on input, less drive is needed to make it get up. And yes, biasing makes a big difference as well. When biased properly, they are already turned on.

stealth
03-01-2013, 10:58 PM
Here's a pic. http://i83.photobucket.com/albums/j312/djw69Nova/2013-03-01_19-08-56_446_zps3fb572f7.jpg

- - - Updated - - -

Here's another http://i83.photobucket.com/albums/j312/djw69Nova/2013-03-01_19-08-04_454_zps38a5ed0a.jpg

- - - Updated - - -

http://i83.photobucket.com/albums/j312/djw69Nova/2013-03-01_19-08-04_454_zps38a5ed0a.jpg

Oh yeah....notice the snipped cap in the back....what's up with that?

Ghost Rider
03-01-2013, 11:18 PM
I picked up a no name amp (looks like a Boomer/Palomar though) with four SD1446 pills in it. Wondering if this would be considered low or high drive? How many watts from the radio should these be fed for longevity?

Well...I'm no radio guru but I looked up that transistor's spec sheet via "Google" and from what I saw....it looks as though at 27Mhz with only 6 watts input, that transistor will produce around 90 watts of output. It is also rated to take an extremely high VSWR with no ill effects. So.....using a little common sense....

I'd say that with four of those type "pills", you could hit them with a PEP of around 24 watts and get appoximately 360 watts of output.

-=PEAKABOO=-
03-02-2013, 01:48 AM
Here's a pic. http://i83.photobucket.com/albums/j312/djw69Nova/2013-03-01_19-08-56_446_zps3fb572f7.jpg

- - - Updated - - -

Here's another http://i83.photobucket.com/albums/j312/djw69Nova/2013-03-01_19-08-04_454_zps38a5ed0a.jpg

- - - Updated - - -

http://i83.photobucket.com/albums/j312/djw69Nova/2013-03-01_19-08-04_454_zps38a5ed0a.jpg

Oh yeah....notice the snipped cap in the back....what's up with that?

What cap is "snipped" I can't see it in the pic, I'm on my phone.

Mudder_Trucker
03-02-2013, 02:31 AM
13347

I imagine its this one, Peak. legs dont look to be soldered.

4-400
03-02-2013, 02:46 AM
looks like the swamp resistor on the low side of the low/high/med power switch has been overheated .....ala over driven ...could be just camera angle

Crusher
03-02-2013, 02:55 AM
That electrolytic was probably parts of SSB delay. Probably kept relay keyed for an extra second or so, its not needed unless you talk sideband. That looks like a boomer 350 or 400. Yup, a 4W carrier and about 20-30 pep is all you need. 350-375 pep is about right for that amp. That would be considered a low drive amp. Also it looks like that amp has unregulated biasing. Class B at best, but poor design so don't think about volting it.

stealth
03-02-2013, 10:55 AM
Thanks. Sounds like this amp might be the ticket. I was looking for one that I could use my stock Uniden PC68LTW to drive, w/o having to go inside and try to find the dead key adjustment.

And yes for those asking, the snipped cap is the one in the 2nd pic that is under the power wires. Look closely, it's the leg closest to the rear of the radio.

stealth
03-04-2013, 01:00 AM
Figured I'd post my findings. Hooked this amp to my 23 ch JC penney base that has a 3 watt carrier and a 10 watt modulation. Used an Astron RS20A to power it.

On low on my meter the amp deadkeyed to 50 watts swinging to 150. Put it to medium it would do 100 watts swinging to 400 but then on high it would show 100 swinging to 500....that doesn't sound right does it? (this was after calibrating the meter)

Also I noticed my SWR was high with the amp on. Turn it off I have a 1.3:1 SWR. My antenna is a Imax 2000. Feeding ti with LMR400 line.

Mudder_Trucker
03-04-2013, 01:36 AM
Figured I'd post my findings. Hooked this amp to my 23 ch JC penney base that has a 3 watt carrier and a 10 watt modulation. Used an Astron RS20A to power it.

On low on my meter the amp deadkeyed to 50 watts swinging to 150. Put it to medium it would do 100 watts swinging to 400 but then on high it would show 100 swinging to 500....that doesn't sound right does it? (this was after calibrating the meter)

Also I noticed my SWR was high with the amp on. Turn it off I have a 1.3:1 SWR. My antenna is a Imax 2000. Feeding ti with LMR400 line.


SWR is always high with an amp on. In most cases. Take the amp out, hardwire from radio to antenna, make sure the SWR is good, then put the amp back in.

MORTIMUSMAXIMUS
03-04-2013, 06:58 PM
My Magic Meter tells me how many watts to drive a box. The meter knows all. He makes sure the Genie stays in the bottle.

stealth
03-24-2013, 10:06 PM
That electrolytic was probably parts of SSB delay. Probably kept relay keyed for an extra second or so, its not needed unless you talk sideband. That looks like a boomer 350 or 400. Yup, a 4W carrier and about 20-30 pep is all you need. 350-375 pep is about right for that amp. That would be considered a low drive amp. Also it looks like that amp has unregulated biasing. Class B at best, but poor design so don't think about volting it.

Hey Crusher,

Any reason why someone would have snipped the cap?

Thinking about using this with an RCI-2950 I picked up unless there's a better amp to use. Plan to do both AM and SSB. The 2950 swings to 25 so hopefully that's not too much.

tfastlane
03-24-2013, 10:30 PM
It's probably like crusher said, it's one of those so called automatic sideband delays witch is nothing but a cap that stays inline all the time and makes it unkey slower. They weren't gonna use it on sideband so they snipped the cap to make it unkey faster. I have to ask this because you always start with the most obvious thing. When you said the SWR goes up when you turn the amp on, did you recalibrate the meter after you turned it on?

Sprinter
03-25-2013, 10:23 AM
All hail king cobra just slap it inline and have at it. It must be so cuz it said so on the Internet. Forget trying to go at it carefully, and adjusting the dead key is way too much trouble or work. Especially when all the directions and close up pictures on the net make it look so difficult. The spec sheets are the word of the gospel. I just hope we know how to interpret the data.

stealth
03-31-2013, 01:37 PM
Thanks fellas.

One other thing I want to ask...how many amps of current do you suppose this amp pulls?

I noticed it has 12 gauge power wire that comes ut of it. The solder joint looks factory. However when I key up this amp I notice it pulls some current, as the lights dim a little and the engine bogs down a little bit.

So now I'm curious as to how much current this needs to work and if I'm feeding it enough....?


When you said the SWR goes up when you turn the amp on, did you recalibrate the meter after you turned it on?

Yes I did. But perhaps the SWR meter was lying to me....I was able to make a contact with this amp in my mobile to another mobile operator at 15 miles....If I'm not mistaken i don't think i could have made that trip on a high SWR...unless there's something I'm missing.

rifleman223
03-31-2013, 02:34 PM
Take a look at the "PCB Layout" of the Palomar 400 here:

http://www.cbtricks.com/Amp/palomar_other/400/index.htm

Looks EXACTLY the same as what you have.

As far as amp pull, I would have to est. 40 amps... What size fuse do you have on it ? You know it is pulling LESS than what the fuse is rated at...

stealth
03-31-2013, 02:54 PM
Yeah I saw that CB tricks write up this morning. I have a 30 amp fuse in line.

central wi 544
03-31-2013, 03:36 PM
you need a way bigger power supply

booger d
04-01-2013, 02:41 AM
I would advise changing the power leads , All the crimp connectors add resistance and isn't very trustworthy. change the wires and add a fuseable link. make sure you use the same gauge wire.

-=PEAKABOO=-
04-01-2013, 02:49 AM
I would advise changing the power leads , All the crimp connectors add resistance and isn't very trustworthy. change the wires and add a fuseable link. make sure you use the same gauge wire.

What gauge wire and where would you suggest adding the fusable link?

stealth
04-06-2013, 11:20 PM
I would advise changing the power leads , All the crimp connectors add resistance and isn't very trustworthy. change the wires and add a fuseable link. make sure you use the same gauge wire.

Thanks. I spent this morning removing the old wiring, which was a 10 gauge for the ground and a 12 gauge for the power. I still don't understand why there were 2 different sized wires or even why there was 12 gauge on the power side.

In it's place I soldered in two 10 gauge wires. Perhaps now this amp will perform a little better. I'm sure it had to be starving for electricity when I'd key up.

I even resoldered back the cap for the auto SSB. Oh and I solder all my connectors too. No crimping here.