Stryker sr94hpc

I connected the stryker sr94hpc to my diy 450watt dummy load (with built in rf reading components) which is more accurate than a bird meter, and read the dead key and peak for this radio.

4watt setting = dead key 4watts, swing to 20
10watt setting = dead key 10 watts, swing to 48 watts.

Transient peaks of 72 watts.
To eliminate distortion simply by turning down power mic.

This mod makes the max mod operate like childs play.

Iceburgh said:

I connected the stryker sr94hpc to my diy 450watt dummy load (with built in rf reading components) which is more accurate than a bird meter, and read the dead key and peak for this radio.

4watt setting = dead key 4watts, swing to 20
10watt setting = dead key 10 watts, swing to 48 watts.

Transient peaks of 72 watts.
To eliminate distortion simply by turning down power mic.

This mod makes the max mod operate like childs play.

Click to expand...

But what does it look like on an O'Scope?

I'm betting something like this...

Because the mod only increases the range of the AMC without disabling it, the radio can easily be set for clean audio and still be noticeably louder than stock. If you do over modulate it, the rig usually hits RF cutoff long before it flat tops at the 10 watt carrier level. If you're using the mic gain to reduce this distortion, chances are the AMC is now set too high. Ideally the AMC should be preventing this distortion and you can keep a little extra mic gain for added compression and talk power. That assumes the background noise is not objectionable. Last bit of advice is do not set the carrier for more than 10 watts. If you're long winded, 8 watts may be better. While the electronics have the headroom to reproduce strong positive peaks, the heatsink does not! It gets hot even stock because of that carrier and small heatsink.

I did this Mod using a 1kohm trimpot and adjusted it using an O-Scope, this mod works great.

what is the motorola pre-amp that shockwave was referring to?
LC

loosecannon said:

what is the motorola pre-amp that shockwave was referring to?
LC

Click to expand...

The needed pre-amp parts are all on the left side of this schematic. They include everything from C1301 to C1308. VR1301 is not used. Amplified audio output comes from the ungrounded side of C1308. That cap is too large at .15uf and attenuates lots of the high end content. As I recall, a .047 worked much better here. C1305 controls how much bass passes through the circuit. Adding a variable resistor in series with C1305 allows adjustment of gain if needed. Q1302 is just a general purpose NPN. The old 2N2222A or equivalent will work fine.

The right hand side of the schematic contains a transmit switching transistor and "Private Line" switch for receive as used in a Motorola radio. They are not needed in other radios. This pre-amp can be built "dead bug" style on the backside of the stock mic board. It can fit if you remove the metal weight in the back of the stock mic and Dremel out a little of the extra plastic ribbing inside the mic. I did have to add a small copper shield made of roof flashing, soldered to the ground on the PC board and covering over the pre-amp to prevent RF feedback.

The stock mic element can be reused in place too. Just cut the circuit trace on the back of the board to insert the pre-amp in between.

thanks for that shockwave, im assuming that MK1301 is the mic element itself, but the schematic symbols are throwing me off a bit.

seems like this circuit could be made super tiny if SMT parts were used.
LC

loosecannon said:

thanks for that shockwave, im assuming that MK1301 is the mic element itself, but the schematic symbols are throwing me off a bit.

seems like this circuit could be made super tiny if SMT parts were used.
LC

Click to expand...

Correct on both accounts.

As an update covered in another thread indicates, I can no longer recommend this radio in any application where impulse noise interference is present. Such as, most vehicles. The radio clearly suffers from no functioning Noise Blanker and that switch, has been deceptively wired to an unadvertised ANL circuit, in a feeble attempt to cover up this deception.

Shockwave said:

As an update covered in another thread indicates, I can no longer recommend this radio in any application where impulse noise interference is present. Such as, most vehicles. The radio clearly suffers from no functioning Noise Blanker and that switch, has been deceptively wired to an unadvertised ANL circuit, in a feeble attempt to cover up this deception.

Click to expand...

What about a capacitor in the DC supply line? (I have not tried to put this in a mobile yet, just got it )

86lidewell said:

Is this the correct place to solder in the 470ohm resistor? Thanks!

Click to expand...

Well, you are pointed at the right transistor but not on the correct solder pad. As your photo is orientated, the part in question has two pins on the left, one over the other and one center pin on the right. You want to connect the new resistor from the lower left pin of that transistor, to the ground screw.

Shockwave said:

Well, you are pointed at the right transistor but not on the correct solder pad. As your photo is orientated, the part in question has two pins on the left, one over the other and one center pin on the right. You want to connect the new resistor from the lower left pin of that transistor, to the ground screw.

Click to expand...

I see. Attention to detail does not go well with ADD.

86lidewell said:

What about a capacitor in the DC supply line? (I have not tried to put this in a mobile yet, just got it )

Click to expand...

Unfortunately there is nothing that can substitute for the missing NB function this radio was falsely advertised as having. The type of interference in question, does not typically come in on the DC line. It is static impulse interference generated by a wide range of things found in every vehicle. They include everything from brushed motors to the electronic ignition system firing your spark plugs. While this type of impulse interference is very easily removed, it must be done with an effective NB circuit within the radio, so that it can mute the interference in the correct stage of the radios receiver.

Shockwave said:

Unfortunately there is nothing that can substitute for the missing NB function this radio was falsely advertised as having. The type of interference in question, does not typically come in on the DC line. It is static impulse inference generated by a wide range of things found in every vehicle. They include everything from brushed DC motors to the electronic ignition system firing your spark plugs. While this type of impulse interference is very easily removed, it must be done with an effective NB circuit within the radio so that it can mute the interference in the correct stage of the radios receiver.

Click to expand...

yes, makes sense. I hear an electric motor sound in my Subaru and the dodge diesel has all kinds of crazy noises plaguing my radios. Nothing has helped in the least so far except the ignition key.

I DID notice the NB on this radio actually quieted the receive some on the bench.

86lidewell said:

yes, makes sense. I hear an electric motor sound in my Subaru and the dodge diesel has all kinds of crazy noises plaguing my radios. Nothing has helped in the least so far except the ignition key.

I DID notice the NB on this radio actually quieted the receive some on the bench.

Click to expand...

What you noticed is the switch has been misused to activate an ANL (Automatic Noise Limiter). What that very cheap ANL does, is clip all sound coming out of the speaker, to one preset level determined by the limiting diode. The end result is the interference is not louder than the normal volume, it's perfectly equal to it. You'll notice when you turn on the lying NB switch, it changes the sound of everything coming through the speaker, due to the distortion the diode creates clipping off all of the peaks.

The true test to determine this radio has no noise blanker function ability whatsoever, is the fact that no matter what type of interference you are receiving, the NB switch will NEVER have any ability to reduce the noise floor, on the signal meter. Any decent NB circuit will have the ability to reduce impulse noise level, by several S-Units, when that interference is strong. Good ones, will remove enough of that interference, so you can't even tell it was ever there and you can hear all of the signals that were underneath that noise level.