Palomar RFX95HD

[Shadetree Mechanic]

Is this the 86V with the RFX95HD mounted to the back of it? What are you getting out of it for power with it? Thanks.

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Yes, I am getting just under 100w peak on my Autek meter. It is still in my truck, the Ares2 with RFX95HD had a totally different set of problems and has been sidelined for now.

 

[Eldorado828]

I'm on an rfx95hd and a Cobra 29 ltd classic.

The problem goes like this.
Rfx turned off, about 1/2 watt carrier swings to about 18/20 pep. Rfx on I get no carrier at all but swings up to about 70 pep.

This 29 was done by Bell's before I put the rfx95 on it. He did a swing mod which brought down the dk but I'm not 100 percent what his swing consists of. I see jp36 replaced by an electrolytic cap (100uf 25v).

Do I need more drive to get the rfx to give some carrier?

Comments, suggestions welcome

 

[Shadetree Mechanic]

I believe it wants to see about one and a half to two watts carrier from the radio.

 

[Eldorado828]

I believe it wants to see about one and a half to two watts carrier from the radio.

I was hesitant to touch screwdrivers work but I'll attempt to bring the radio carrier up to your suggestion. Tomorrow I'll go back to it and report back.

I don't have much experience on the 29 or cobras, never has been a go to radio for me but I got a deal on this one.

 

[Hawkeye351]

I think it's C62 that you need to apply more capacitance to in order to increase the carrier. It's back in the corner where the driver is at. The following is for an RFX75 on a 29, but the carrier info is the same regardless of which RFX you're using.

In my experience with these RFX95HD amps, don't exceed 18w deadkey out of the amp. I think 15w deadkey sounds better though. And don't get long winded, the thermal protection in the amp will kick in and drop your wattage. The 9530 MOSFETs in them are pretty rugged transistors, I've had a few operators hammering on them, running them hot to the point the amp shuts down, but after cooling off for 15 minutes they would come right back to life. Amazon has some fans that will fit the amp if need be, they're around 12 bucks for 2 fans, and you will be using both.

https://cbtricks.org/miscellaneous/accessories/power_band/rfx_75/graphics/rfx75_cobra_29_carrier_increase.pdf

 

[Eldorado828]

I think it's C62 that you need to apply more capacitance to in order to increase the carrier. It's back in the corner where the driver is at. The following is for an RFX75 on a 29, but the carrier info is the same regardless of which RFX you're using.

In my experience with these RFX95HD amps, don't exceed 18w deadkey out of the amp. I think 15w deadkey sounds better though. And don't get long winded, the thermal protection in the amp will kick in and drop your wattage. The 9530 MOSFETs in them are pretty rugged transistors, I've had a few operators hammering on them, running them hot to the point the amp shuts down, but after cooling off for 15 minutes they would come right back to life. Amazon has some fans that will fit the amp if need be, they're around 12 bucks for 2 fans, and you will be using both.

https://cbtricks.org/miscellaneous/accessories/power_band/rfx_75/graphics/rfx75_cobra_29_carrier_increase.pdf

Thank you sir, you pretty much gave me a cheat sheet for this one. I was going to attack the how to tomorrow but now I'll jump straight into it.

 

[Hawkeye351]

Np eldorado, anytime

 

[Eldorado828]

Well fellas I played with capacitance at c62 for a little while and found that it has very minimal affect. So now, I'm looking over to see what was done by the shop and try to reverse some of what was done. I see the capacitor at jp36 and a resistor on the foil side. What else is done I'll find out shortly.

 

[Shadetree Mechanic]

I believe the resistor value sets the carrier level.

 

[loosecannon]

Eldorado,

yes that resistor added to the solder side of the board is the one to change the value on in order to raise the deadkey.

less resistance equals higher deadkey.
LC

 

[Hawkeye351]

Sorry that didn't help out El. It worked on 2 I did, the others didn't need any change.

 

[Eldorado828]

I'll get back on it later tonight and play with it some more.
I did however lift one leg of that resistor and noticed I lost all the carrier so I tacked it back down.

I'll report back.

 

[Hawkeye351]

The others are correct in telling you to change out that resistor to a lower value.

Try 68 ohm, if still not enough key then try a 33 ohm.

 

[Enterprise312ok]

Try a 68 ohm or around that, usually they end up between 33 and 150 ohms. I do not like that swing mod myself, not much average swing and does not look good on the scope. The better mod uses a tip120 transistor a 220 ohm electrolytic a 100 okm resistor and a 5k to 10k potentiometer to set the dead key.

 

[Eldorado828]

Ok gents I worked all the way down to 33ohms and all is working well now. I only had a 33 ohm in 1/8 or 1/4 watt 5%, the 1/2 watt or 1 watt kits didn't have that value.

I get a carrier both with rfx on or off and will fine tune every when I have a some more time.

Thank you @loosecannon @Shadetree Mechanic @Hawkeye351 you fellas saved me a lot of figure out on this one!