Are there any extra steps left out to bring the carrier up on a 29 ? Have one with erf2030 mod with 2-2.5 dk 20-30 watt swing?
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40-45 watt ERF2030 mod for Cobra 25/Uniden 66/68
- Thread starter Moleculo
- Start date
What kind of meter are you gauging that 30 watts with? If it isn't a true peak reading meter; then it won't show that other 10w. IOW - if you aren't using a true peak reading meter; you can't see the other 10w. BTW - A Dosy meter isn't a 'true peak reading' meter. If you are using a Dosy and it is showing 30w; then it is probably in reality putting out an additional 5-10w on top of what the meter shows. Another thing; are you testing the radio with a meter AND a 50 ohm dummy load? If not; then the results will create some variance in the reading too . . .
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The IRF 520 mod
Hello evreyone, I recently preformed the IRF 520 mod to a cobra 25 LTD ( that i just bought ) & I made sure I followed step for step.Long story short (IT DID NOT WORK).Very disipointed.When I was finished ,the radio would key up but had no power.I'm wondering if I got a batch of bad IRF520's or is it that the IRF520 is not copatable with the 470ohm ,3.3k & the 1n4148 bias that I made? Thank you for your time ,yepshoot435 ^^ ab v c^^
Hello evreyone, I recently preformed the IRF 520 mod to a cobra 25 LTD ( that i just bought ) & I made sure I followed step for step.Long story short (IT DID NOT WORK).Very disipointed.When I was finished ,the radio would key up but had no power.I'm wondering if I got a batch of bad IRF520's or is it that the IRF520 is not copatable with the 470ohm ,3.3k & the 1n4148 bias that I made? Thank you for your time ,yepshoot435 ^^ ab v c^^
If you can't double your power as easy as falling down then it ain't worth screwin' with.
If the Smeter was as indicative as the wattmeter it would be worth the time and the money, but it ain't.
If the Smeter was as indicative as the wattmeter it would be worth the time and the money, but it ain't.
Radioman, people don't understand that these mosfet final mods are really more of a final replacement mod then a "high power" mod. If you have a working radio you roll with it. If you smoked your 1969 then you consider a mosfet conversion.
If the radio was doing 35 watts with a 1969 final mod, and after this mosfet mod it does 40-45 your not gonna kick any a$$ with 10 more watts. Heck, I would take a nice Cobra 29, receive mod, audio mod, tune and alignment. Take that 2 watts swinging 20-25, run that into a Texas Star 350 and BAM..............your done.
My example is also assuming that EVERYONE that does a mosfet mod can get 45 watts. I have had several radio that different well known shops did a mosfet mod to, I was told 40 watts for one and 45 for the other. Neither would crack 30 watts on my meter. Maybe on a dummy load at 15 volts sure, we don't talk on dummy loads though.
I agree 100%
If you double your power you really ain't done squat and to think that adding 10 or 15 watts to your already 30 watts is gonna do anything substantial for you is just hopeful thinking and naive.
Hi, I'm still working in my Uniden PC66a (IRF520N Mod).
In order to get a boost from the output, I installed a capacitor in parallel (33 ~ 100pf) at C46. At C42 location, I installed 10pF in parallel.
Greetings from the Caribbean
Thanks for the info.
That is good useful and inciteful information.
Should serve to illustrate that after you have done the mod letter for letter that it will most likely take some adjustment (experimental or trial-and-error tweaking ) of some component values to get it to work well.
Hi, I'm finish my Uniden PC66a (IRF520N Mod).
I used a different values 500 ohms + 1n4148 + 350k, something in between the EN369DR and EN369FN.
At first I was disappointed 3W and 8W modulated, but after some changes (added 330 pF) in parallel at C46 and 10pF in parallel at C42 the output is now 5W and 20W modulated. Limiters, coils and everything else are intact.
As for Moleculo instructions, added 10k resistor at R38, instead of just removing the tuning slug from L10, take a turn off the coil and keep the slug to fine tune the output. Radio is finished now and fine tuned. 6.5W and 30W modulated in my Peterson WM-1.
Greetings from the Caribbean<gotproof>
I used a different values 500 ohms + 1n4148 + 350k, something in between the EN369DR and EN369FN.
At first I was disappointed 3W and 8W modulated, but after some changes (added 330 pF) in parallel at C46 and 10pF in parallel at C42 the output is now 5W and 20W modulated. Limiters, coils and everything else are intact.
As for Moleculo instructions, added 10k resistor at R38, instead of just removing the tuning slug from L10, take a turn off the coil and keep the slug to fine tune the output. Radio is finished now and fine tuned. 6.5W and 30W modulated in my Peterson WM-1.
Greetings from the Caribbean<gotproof>
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I do agree with the one gentleman ,the traditional 1969 fixer upper is the best . I'v had lots of success with it in many radios .The problem being,: The radio came with the stock 2078 and I didn't have any 1969's on hand but I happened to have plenty of IRF520's.That is the only reason why I chose that method. We live & learn
bout to do a mosfet on a 25gtl. just sanded the bezel and hit it with self-etch primer and vht expoxy paint, took magwheel polish to the faceplate to shine it up.
so i find that to do an NPC-RC mod cleanly with a mosfet, i find that biasing is needed. using hard resistors inplace of the companion kits is better. so from the 8vtx point, i ran a 4.7k to the gate, and a 3.9k to ground, 470ohm-1n4148. and the bypass cap to link the driver-final gate needs to get increased to let more juice through. when i tried with the class C layout, the audio was a little rough. i only made that mistake once and now im running bias on them
why is this thread not pinned like the 29 thread is?
so i find that to do an NPC-RC mod cleanly with a mosfet, i find that biasing is needed. using hard resistors inplace of the companion kits is better. so from the 8vtx point, i ran a 4.7k to the gate, and a 3.9k to ground, 470ohm-1n4148. and the bypass cap to link the driver-final gate needs to get increased to let more juice through. when i tried with the class C layout, the audio was a little rough. i only made that mistake once and now im running bias on them
why is this thread not pinned like the 29 thread is?