Erf 2030 ?

[Scott45]

I would like to try this to get a higher dead key.

1) Add a 4.7K ohm resistor (1/4 watt) from the positive side of C116 to the gate of the ERF-2030 (this is the left-most leg when looking at the face of the ERF-2030).

2) Remove the capacitor at C62, and replace it with a 390pF capacitor. Also, make sure that there are no additional capacitors tacked on the solder side of the PCB (sometimes Cobra adds additional capacitance at this part to get everything to tune-up correctly). If there is an additional capacitor on the solder side at C62, then remove it.

3) Remove diode at D8, and replace it with a jumper. Or, just add a jumper wire across D8.

We have had good success with these additional steps and it gives everyone the carrier level that they are looking for."

My Question is when you Remove the capacitor at C62, and replace it with a 390pF capacitor. The new Capacitor is 390pf but how many volts.

 

[Space Cadet]

Should be a ceramic, 50V or better should be fine.

 

[speedracer6g]

Hey guys i just wanted to chime in here i would recomend not jumpering d8 it can cause your radio alot of problems. if you remove the antispiking diode it can blow out you audio chip and fry your mod transformer. i have seen it too many times. besides i get just as good of results without doing it anyway.

MIKE

dont mean to step on any toes but just a warning for the guy who ownes the radio. it will only gain you a watt anyways. and is a extra watt worth blowing the radio???

 

[speedracer6g]

4.7k resistor change.

just found out that you will want to change the 4.7k oum to a 10k pot. you will want to set the Vgs voltage to about 2.7 to 3.0 max. if you do the 4.7k it runs between 3.2 and 3.6 and the final runs too hot. i blew a couple erf2030s the other way and now it seems to work fine with the lower bias voltage you will loose some power but it is more stable. At least you wont be changing parts every couple of days. I used a 4.7k and a 5k pot to set mine but that is what i had laying around You can use whatever combination you want i just used the 4.7 to keep the bias voltage set to a min level until i got it dialed in.

MIKE

 

[seedkey]

so what did your dead key end up being?

 

[speedracer6g]

Well the higher the bias voltage is the higher your deadkey but you should not go any farther than 3.0 volts if you do it runs too hot. and we know what happens next. mine runs around 5 watts deadkey and swings to 16 rms dont know what the pep is waiting on my bird 43p to show up. i am guessing around 40-50 in that range radio sounds good and i get out almost as good as my kl-200p linear. so for what it is worth i would not worry too much about the deadkey as long as the power with the audio is good and dont overmodulate the final with a swing kit they are junk. if you know someone with a good scope set your mod with it the waveform should be smooth no jagged edges or anything like that here is a good website with some pictures that will show you what your waveform should look like.

http://www.icycolors.com/nu9n/scope_your_audio.html

hope this helps

MIKE

 

[bettyeboop]

I have a uniden 66 with the 520 final added as to the instructions.....i have almost no dead key and only 8 watts swing on my bird 43.


where is c116 please.......

also the c 62 disk cap


I have tried the deprom super swing kit that uses a 510 transistor some parts and a pot to adjust dead key........I put the jumper back and it did not change anything other than in the min pos it killed what little i had.


Question:

can i change the pre driver out with a 510 transistor....or something stronger.

 

[bettyeboop]

I meant to say that with the super mod setup i get a little more power.....with the jumper put back to its original posistion I lose some of the little bit of swing i have.

 

[AudioShockwav]

Well the higher the bias voltage is the higher your deadkey but you should not go any farther than 3.0 volts if you do it runs too hot. and we know what happens next

It is called
EXPLODE ! !

Thanks to Nomad for the photos.

73
Jeff

 

[KC2OST]

It is called
EXPLODE ! !

Thanks to Nomad for the photos.

73
Jeff

thats wild..

 

[Crusher]

LOL I did that to a several sets of 520's, when I was working on a project awhile back. LOL I bet that thing was smoking.

 

[ElectrikTec]

Thats a kewl pic. I have seen some 2sc1969's with a huge hole in them, and TA7222AP audio amps with giant parts of them missing.. and some 2sc2879's that had the tops blown right off them ! it's amazing what a semiconductor will do when the fuses are jumped out and the conditions are right !! lol....

 

[AudioShockwav]

I can not take credit for the picture, chris ( nomad radio ) shot the picture from a Magnum radio that he repaired.....


From Nomad Posted At CBTricks.com:


.

As for the "TGM", I just recommend turning it off. They DID put it on a switch, after all.

Best I can tell, the TGM is good for blowing up finals in radios using MOSFETs. This guy kept putting in larger fuses when they would blow out in his Magnum.