Stryker sr94hpc

[Shockwave]

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

The picture in that post, does show the correct location to install the resistor.

 

[86lidewell]

The picture in that post, does show the correct location to install the resistor.

Thanks! I deleted the prior post to eliminate confusion with the placement.

 

[86lidewell]

Here's a picture of the adjustment pots. I wonder what W3 does. Anyone know?

 

[86lidewell]

WOW! so glad I did the resistor ALC mod mod(sic). on low power, which I set at 1w, the thing swings to 30. Not much test and verification other than a "loud and clear" radio check done yet.

 

[Shockwave]

WOW! so glad I did the resistor ALC mod mod(sic). on low power, which I set at 1w, the thing swings to 30. Not much test and verification other than a "loud and clear" radio check done yet.

That's enough forward swing to insure a good amount of negative peak cutoff. On low power I set the carrier to key 6 watts and set the AMC to peak 25 on the Bird 43P. As you can see, the radio can easily overmodulate now, if the AMC is set too high, or the carrier is set too low.

 

[86lidewell]

I'll keep that in mind. The idea is to see what it will do with a 2 stage amp on each stage.

 

[N9XCR]

Has anyone done a direct inject audio mod to this radio?

 

[Shockwave]

Has anyone done a direct inject audio mod to this radio?

Probably not yet, but the fact it uses a series pass modulator, says you can inject outside audio by driving this stage. Results would just be limited by what you feed into it.

 

[Shockwave]

Just noticed a unique quirk with the volume control on this radio. When turning the volume all the way down, the number just below one, is not zero. It's 59! When you want to turn it all the way down, the normal action to do that, produces the exact opposite effect of full volume. That was like an instant two coffee adrenaline rush late last night. It also explains why the default knob setting is not for volume and why they configured the power switch as a mute button when momentarily pressed. It is the only way to turn the volume all the way down.

 

[Zonie]

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

I've tried that, and a choke. No love. It is a great little radio, but only for stationary use. It picks up too much noise from the vehicle.
Has anyone had any luck correcting this?

 

[Iceburgh]

My SR84HPC Stryker now performs better than all my other radios after the real modulation modification.

 

[Squints]

Removing modulation limiters do not always distort every radio theyre removed from somtimes the removal brings a radio to life like the president ronald

 

[Eldorado828]

My SR84HPC Stryker now performs better than all my other radios after the real modulation modification.

Just curious as what you're calling the "real" modulation mod?

 

[Smack32]

Most modulation limiters prevent distortion. However, the one in the SR-94HPC simply prevents good performance. After reading people rave about this radio "having the strong AM audio Stryker is known for", I bought one. What a disappointment. It has the strongest modulation limiter is more like it.

This lack of strong modulation was not acceptable so I looked around for a schematic to no avail. When that didn't work I pulled the board and tried tracing the circuit from the mic input looking for the attenuation transistor. This board may be three layers because lots of traces disappear from the top of the board to the bottom. Like connections must be happening in the middle.

When that failed, out came the scope to trace the audio from transistor to transistor. Luckily, the desired one is on the top of the board. On the extreme front edge of of the board to the right of the white ribbon cable is a transistor. Two legs face the front edge of the board while one faces the rear. It's the leg on the right front edge of the board we are concerned with.

Solder a 470 ohm resistor to the pin on the bottom, right side of the transistor and ground the other side of the resistor. You could use the screw in the right front corner of the board to ground this side of the resistor. This loads the drive triggering the transistor to conduct and was the safest way I could find to increase the range of both AMC controls without defeating the AMC. It will distort if defeated.

Now the radio screams like 45 watts PEP should. Plenty of range on the controls so they can be set on the scope without distortion. If someone wants to post a detailed picture of this area of the board, I'll point out the location of this transistor a bit better. You should remove the ribbon cable and front panel when installing this resistor otherwise the soldering iron may burn both.

I just pickedup this radio .. Did the 11 meter mod and tingd the vr s for max out.. Would you have a Pic of the transistor in question ? Hate going in blind just looking for a reference ..
Thank You

Attachment is fot the vs I adjusted

 

[Eldorado828]

I just pickedup this radio .. Did the 11 meter mod and tingd the vr s for max out.. Would you have a Pic of the transistor in question ? Hate going in blind just looking for a reference ..
Thank You

Attachment is fot the vs I adjusted

If you just go through this thread you will find everything you need to know.