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Blew my 503

Just started running a 503hd behind my Stryker 955hpc. So far I'm liking it and they seem to play well with each other. This is my 1st amp and figured I'd go with the hd since I'd only be running it with exports. I really like the adjustable output,although if you read the instructions that's not really what it is.


Living dangerously: remember to let the blue smoke out at 70-mph while trying to keep 77,000-lbs corralled. While smoking. Drinking coffee. Yakking over telephone headset with another driver. In traffic. With a 20-knot crosswind. And a half-eaten McSandwich on the dash. In other words, a snapshot out of a typical morning.

And you reach for the radio volume to turn up a report, hit a bump and grasp the wrong knob . . .



I went with a 30A fused RM ITALY KL7505v. After a Galaxy 99v2.

Amp has three position power switch. Radio has variable power.

On the bench, with radio at lowest setting, and amp in lowest it’s:

2.25w, keying 15
into
40w, keying 180

A “better” radio someday (though it was a distinct step up from before). Was simply glad this (and the rest) was working to spec (on frequency).

Wouldn’t hurt to check numbers on yours, is thought.

Which reminds me. Ran across a post about ARRL procedure to tune both to a 1:4 ratio. Worth opening them up?

.
 
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Living dangerously: ... [ ... ] ... a half-eaten McSandwich on the dash.

In other words, a snapshot out of a typical morning.
And you reach for the radio volume to turn up a report, hit a bump and grasp the wrong knob . . .

It sounds like it's not even safe to run the full power of the 955 through that amp. I wonder what happens to the amp if you do?

Your McSandwich develops Grill marks from laying on the amp - with it's wrap smoking - slowly filling the cab with an odor. And the smell? It's not McDonalds French Fries...
 
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Your McSandwich develops Grill marks from laying on the amp - with it's wrap smoking - slowly filling the cab with an odor. And the smell? It's not McDonalds French Fries...
That was a serious question. Does the amp just arc out and fry everything? I have ran well over 100 watts passing through a ts350 and a ts500 with no ill effects. Why can't the 503 handle 100 watts with the amp turned off?
 
I was not being facetious - I was being serious too.

Full power with that amp off? The capacity of the relay is the limit.

So it won't heat the parts bonded to the heat sink...but there may be RF heating...

My post was referring to what the OP did, and re-creating it in a cab environment.

The things got fuses, yes, but turning up the power on the radio with the amp on will recreate the scenario above easily enough - and the smell others referred to in the thread will mix with the smell of the latest meal - if not re-start the cooking process.
 
I was not being facetious - I was being serious too.

Full power with that amp off? The capacity of the relay is the limit.

So it won't heat the parts bonded to the heat sink...but there may be RF heating...

My post was referring to what the OP did, and re-creating it in a cab environment.

The things got fuses, yes, but turning up the power on the radio with the amp on will recreate the scenario above easily enough - and the smell others referred to in the thread will mix with the smell of the latest meal - if not re-start the cooking process.
Which relay is this? This is the first amp I have seen a pass through wattage limit advertised. I wonder what the pass through capabilities are of Texas stars and ham amps are.
 
IF you run with the amp off - bypass it's fine...

The problem lies in throwing power - either dynamic or straight carrier - into that thing turned on.

It will heat up and I do not see any thermal limiters anywhere in that amp.

If you don't believe me, get an Infra-red thermometer reader, install the amp into the system and aim the unit at it and start the process - keying up at various power levels and hold it.

It (those fins) can approach at times 180 degrees F - enough to kill most bacteria. And reheat a simple French fry caught in the fins.

This kinda thing happens all the time at key downs - there are amps out there that have their anodizing change color after a battle. The repeated cycle of heat to cool to heat can fatigue the heat sink until it can't do it's job anymore - cheap alloyed alumina remelts from old rims is what some would call it...the metal itself looks "Crazed" with tiny cracks especially where the flanges and their screws meet/held them to the spreader.

The "HD" part just repositions the loss onto another spot with a composition resistor array - go back and see the 503 component side, that's the resistor array to force the driver to run in various levels of drive - the rest is in the combiners to the left of the Driver.
 
There are two - black on the bottom left, White on top left...

Black handles the antenna switching - but note the ratings...
Goodsky.jpg

The Relay is "Goodsky" brand - so 2 amps but if you're running RF that's different...

You haven't seen this yet?
kl503schematicmod_zpsb6355ddf.jpg

You can find it here...
KL503 junk

But it does bypass...
 

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  • RelayGSEC-S-A0000328308-1.pdf
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IF you run with the amp off - bypass it's fine...

The problem lies in throwing power - either dynamic or straight carrier - into that thing turned on.

It will heat up and I do not see any thermal limiters anywhere in that amp.

If you don't believe me, get an Infra-red thermometer reader, install the amp into the system and aim the unit at it and start the process - keying up at various power levels and hold it.

It (those fins) can approach at times 180 degrees F - enough to kill most bacteria. And reheat a simple French fry caught in the fins.

This kinda thing happens all the time at key downs - there are amps out there that have their anodizing change color after a battle. The repeated cycle of heat to cool to heat can fatigue the heat sink until it can't do it's job anymore - cheap alloyed alumina remelts from old rims is what some would call it...the metal itself looks "Crazed" with tiny cracks especially where the flanges and their screws meet/held them to the spreader.

The "HD" part just repositions the loss onto another spot with a composition resistor array - go back and see the 503 component side, that's the resistor array to force the driver to run in various levels of drive - the rest is in the combiners to the left of the Driver.
ok, maybe it is just misinformation. I can't find an actual manual for this amp. According to this site it has a maximum pass through of 50 watts. I wonder where they got that?

http://www.88radio.com/index.php?route=product/product&product_id=85
 
AT-6666. Even on high, the Anytone is supposed to be 45w SSB. I figure that is what did it.


OK,so it was NOT the receiver that was the issue it is a Transceiver & you turned the Transmit power UP. You made me scratch my head when it was the receivers fault since any amount of receiver power should not have affected the transmit output.Now I get it.

SIX-SHOOTER
 
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OK,so it was NOT the receiver that was the issue it is a Transceiver & you turned the Transmit power UP. You made me scratch my head when it was the receivers fault since any amount of receiver power should not have affected the transmit output.Now I get it.

SIX-SHOOTER
No worries, brother! Took me a whole day to figure out what I did wrong!
 
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