• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
  • Notice: You may not use this site to facilitate the unauthorized selling of copyrighted material including, but not limited to, in the public dxForums, dxGallery, dxChat and private messsages. If you get caught doing this, you will be permanently banned with no second chances. A notice will be placed on the site of why you were banned and any information collected by this site about you will be made known to the copyright holder.

Palomar ELITE 400 HD input wattage?

Robb

Yup
Dec 18, 2008
11,433
3,560
323
Silicon Valley CA, Storm Lake IA
Now explain that one more time without all the techno junk. I'm not trying to be funny here I just don't understand all that technological Gobley goo language
In terms you will understand?
Umm; OK

Its like you are trying to put 10 lbs of $#!+ in a 5 lb bag.

Translation:
The second you try put in - for whatever stupid reason, and they are all stupid reasons - any more than the amp was designed to run, crap begins to flow out of it and not going where you intended nor expected it to go . . .

Same goes for radio mods. Real knowledgeable techs (read: 'few') do know how to alter a radio to get better out of them, but they aren't the same hacking crap mods that some forums both provide and pass for truth. Or some are the right mods, but are still improperly adjusted, so that the end result is netting the same five pounds of unwanted crap. Which in turn gets amped and turns in to even more crap.

Making sense yet?
 
Last edited:

Freddy Texidor

New Member
Jun 22, 2021
11
1
3
58
I just picked up a used 400 and 2 watt dk and swinging to 20 watts and I'm only getting about 250 watts on high. Can anyone tell me if something needs to be changed out. By the way it has 4 MRF 455 9245 Malaysia F pills in it. I believe they are 60watts each.
 

nomadradio

Analog Retentive
Apr 3, 2005
5,204
7,385
573
Louisville, KY
www.nomadradio.com
The layout of this amplifier is two push-pull pairs of transistors. A splitter coil divides the driver power in half to each side.

Typical thing to do first is have a look-see at the output combiner. Usually a doughnut-shaped core with wire windings. Called a toroid.

Should be a resistor that's visibly in parallel with this coil. Usually a 2-Watt part.

If it looks burned, or the color bands have faded badly this indicates a loss of balance between the pair of transistors on the left with the pair on the right.

So long as both sides deliver full power that resistor stays cool. It only sees the difference in wattage between one pair and the other.

And if one side mostly shuts down or falls back in wattage, this difference becomes large enough to fry that resistor.

Doesn't tell you which pair of transistors is the weak side, just tells you that one pair is delivering less power than the other.

Not a lot, but a start. And if that resistor looks bright and shiny, this is not the root of the trouble.

73
 

144inBama

Sr. Member
Apr 22, 2020
582
987
103
52
Lower Alabama
I just picked up a used 400 and 2 watt dk and swinging to 20 watts and I'm only getting about 250 watts on high. Can anyone tell me if something needs to be changed out. By the way it has 4 MRF 455 9245 Malaysia F pills in it. I believe they are 60watts each.

Check to make sure your H L M switch is actually working. I've seen them go bad a couple of times. You'll be set on High but Xmitting on Low or Med because the switch internals took a dump. Check you VSWR with just the radio and Ant, record the reading. Then check your reflect to make sure the input tuning is good (meter between radio and amp) and then check your output tuning (meter between amp and antenna). All 3 readings should be fairly close, if not, there's a problem that needs addressing fast. They're small things but have a huge effect. If the input or output tuning is bad, your transistors can be great but component failure in limiting them.
 
  • Like
Reactions: AudioShockwav

Freddy Texidor

New Member
Jun 22, 2021
11
1
3
58
Thank you guys for the information and a place to start.
Fairly new to all this and interested in learning as much as I can.
Thanks again, Have a Great 4th of July and 73s
 

9C1Driver

Sr. Member
Aug 13, 2008
3,635
1,545
173
I think what he is saying is one is a 60 watt device and the other a 70. (@12.5 volts) So an amplifier that's properly driven to spec that has 4 of those finals will be in the 240-280 watt range.
 
  • Like
Reactions: Robb and Ziploc

kc8mob

Active Member
Sep 26, 2017
70
67
48
39
I think what he is saying is one is a 60 watt device and the other a 70. (@12.5 volts) So an amplifier that's properly driven to spec that has 4 of those finals will be in the 240-280 watt range.

This comes up allot. Sd1446s being 70 watt finals at 12.5Vdc. The sheet does say that. But that's also at 70mhz. Or is it 50? Anyhow 27/28 is allot lower then both as far as a transistor is concerned.

When you operate a sd1446 at a more realistic 14Vdc and at 27/28mhz they put out allot more power.

One thing I do like about the 1446 is its ability to withstand swr environments.

A big trick to big output transistors is feeding them all the current they want and the higher your operating voltage, the more efficient it will be.

So you can drive holy hell out of and demand allot of a power transistor so long as you don't starve it for current and can keep it cool.

Harmonics are a factor in everything and many times like guys say here, that big watt meter reading includes a high level of harmonics.


However if you tune and I mean well, tune the input and output stages of the amp. Big splatter can be prevented. Now it'd be more common with a sd1446 based amplifier because the transistor is rated for service at the 2nd harmonic. Vs. Say a Toshiba 2979.

But regarding a Palomar 4 pill sd1446, I just finished upgrading one with big ass power wire. Ground connection brought directly to the center of the board, final arrangement and also tied the output transformers DC supply for the collectors, directly down from the transformer to where the 8awg positive wire is soldered to the board.

This eliminates the lossy, uneaven current consumption by the current having to flow over small PCB traces. Use a choke to tie the input transformers to ground instead of their floating 10 ohm 1/2 watt resistor to ground method and not I don't mean base/emmitter 10 ohm smoke indicators.

Anyway that amp does everything its rated for with a tuned up 28 watt cobra 25. Now if you drive it with a dual final ranger 2950 delivering 45 qatts, after everything done. 600+ watts pep on an active peak reading meter or 175ish average just flows out of it effortlessly.

If you set them up right, you can feed em the onions for sure. Don't starve them for current and keep them under 100c even though they're rated for 150c.

Most dudes can't supply 50 amps at a constant 13.8Vdc even in their vehicle because they have cheese dick power wire installed, crummy in-line fuses and then the all to common 5 or 10 amp at the most, quick disconnect on the power cord of the amp

So with that said. Most guys won't ever see more then 400 out of this level of amp. And then there are those who really do it right and see allot more.

The real way to go is LDMOS but I'm not there yet.
 
  • Like
Reactions: Eldorado828

AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
7,234
4,763
343
Sierras Near Yosemite National Park
crummy in-line fuses and then the all to common 5 or 10 amp at the most, quick disconnect on the power cord of the amp

Those things are worthless, every single one I have torn apart the connector pins are not soldered or crimped, they shove the wire in the connector and mold the plastic around it,
After a few hours the connector gets hot, and becomes worthless.

73
Jeff
 

freecell

BANNED
Apr 6, 2005
1,922
668
65
non-cartesian cyberspace
www.facebook.com
sd1446 transistor device gain and power
multiplication factor relative to frequency

@ 88 mhz. gain = 9.42 dB. or 8.75X
4W input X 8.75 = 35W output

@ 66 mhz. gain = 10.97 dB. or 12.5X
4W input X 12.5 = 50W output

@ 50 mhz. gain = 12.43 dB. or 17.5X
4W input X 17.5 = 70W output

@ 30 mhz. gain = 13.42 dB. or 22X
4W input X 22.0 = 88W output

@ 27 mhz. gain = 13.52 dB. or 22.5X
4W input X 22.5 = 90W output
 

Attachments

  • sd1446_sgs_thomson.pdf
    59.5 KB · Views: 3
Last edited:
  • Like
Reactions: 9C1Driver

144inBama

Sr. Member
Apr 22, 2020
582
987
103
52
Lower Alabama
The 1446 requires scandalously little drive power at 27 MHz. Now and again someone would ask about a box with two or four of these in it, wondering "can I drive it?". As in, drive it with another amplifier.

I would reply "Sure, straight to the junkyard. Will be a short trip".

73
I was running mine (trying) with a couple of different radios. A 29LTD Chrome @ 18 PEP, a 99v2 @ 35 PEP and a 148GTL @ 12 PEP. I was getting close to the same watts (+/- 10) with the only noticeable difference being the heat generated by the box. The 29 and 148 would get it "warm" but the 99v2 would get it hot with little gain. So, I have my 400 in a box with the 29 and a piece of painters tape on the 400 "Only use with this 29LTD Chrome or 20 PEP max radio with 1 watt dead key" In case I croak over and one of the kids get it or it's sold, they don't screw it up on the first key.
 
  • Like
Reactions: freecell

freecell

BANNED
Apr 6, 2005
1,922
668
65
non-cartesian cyberspace
www.facebook.com
16W into 4XSD1446's rated @ 13 dB. gain into a matched load will produce 320W output. (the minimum gain of an sd1446 = 10 dB.) a fairly accurate determination of the gain of the transistors in an amplifier can be made by following the rate of power output compared to power input. using the example above and using a little math you can determine when the gain of the devices begins to drop, in this case the ratio of input power to output power is 1:20, that is, for every watt of input the output increases by 20 watts. as drive is increased a point will be reached where the output power falls off at a faster rate than the input. this reduction in device gain represents the saturation of the input and the onset of output saturation accompanied by excessive levels of (wasted power) heat in the amplifier.

if you operate the devices in an amplifier in their saturation region you'll need fans.

in an example posted earlier where input was 45W and output was 600W+, let's use the 13 dB. gain figure as a reference and calculate the gain of the devices in this scenario.

dB. gain = 10 log (W output / W input)
dB. gain = 10 log (600 / 45)
dB. gain = 10 log (13.33)
dB. gain = 11.249

this is the result of a drop in gain of only 1.751 dB..
the devices in this amplifier are operating in the saturation region.

compared to this

dB. gain = 10 log (W output / W input)
dB. gain = 10 log (320 / 16)
dB. gain = 10 log (20)
dB. gain = 13.000

the devices in this amplifier are not operating in the saturation region.

if the gain of the devices in the first calculation could be maintained @ 13 dB. the output power with 45W input would be 900W but they cant be and it isn't.

the onset of output saturation begins the nanosecond that the gain of the devices begins to drop, primarily due to (input saturation) excessive input drive levels.
 
Last edited:

dxChat
Help Users
  • No one is chatting at the moment.