Ok so I ordered the parts to do the receive upgrade that WA4GCH and IDIeselman turned me on to.
1- 2sc2999 High Gain, Low Noise Transistor
4- 1N6263 Schottky Barrier Diodes
Total cost under a buck plus 4 for standard shipping.
Approximate time involved 30 minutes.
Now to me, to gain 1-2 S-units in the receive(carrier signal only, not the noise) AND quiet the radio significantly of that natural hiss and noise, I think this could very well be the best 5 bucks I've spent in quite awhile and certainly worth the time!
Shipping takes a week or 2 with standard shipping but I didn't see any reason to up the cost 20 or 30 bucks to get them in 3 days but I seriously can't wait to get this done and see(hear) the results.
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Can anyone with any knowledge of this mod and my radio confirm the parts that need replacing?
This is what I come up with...
TR7 is the receive rf amp that gets replaced with the 2sc2999 transistor making the receive more sensitive.
AM detector D4 and D6 get replaced with the 1N6263 Schottky Barrier Diodes as does D7 of the ANL/NB circuit and should make this radio virtually noiseless.Last edited: Apr 15, 2011
Well, I'm at least interested in hearing your before and after reports-I've heard that it makes far away signals have a similar volume to close ones, without distorting the close ones, which is definitely desirable in a noisy truck. You've got guts doing it yourself, that's all I can say-soldering a PL-259 on without melting it is about the limit of my soldering skills. Can't help you with the positions though, have you tried CBTricks.com?
Thanks for the cb tricks tip guys. I got the pcb layout for my radio there and the location of the components for this mod on my radio from another cb forum and just want to confirm those locations.
I'm a little nervous doing this to my brand new radio and had I known about this mod sooner I would have had Paul do it before it shipped but I'm also fairly confident with my abilities.
It will be a couple weeks before the transistors and diodes get here from futurlec and I ordered enough to do 2 radios.
I'm going to practice my soldering skills between now and then since I am fairly new to this.
I put that RFX75 on an old 25 that didn't work out cuz the radio was bad to begin with. That process called for removing the c10 capacitor from the RFX75. I've since removed it from that 25 and want to put it on a known good uniden pc68xl I have and it DOESN'T call for removing that capacitor for some odd reason so I picked up a pf100 capacitor from RS yesterday to replace it and that should be interesting to do on the RFX75 while in that heatsink. I think there's just enough room to do it tho without removing it from the heatsink.
Then I'm going to put the RFX75 on that uniden and see how it goes. All this will further sharpen my soldering skills and boost my confidence if it actually works this time. lol
Using a used and removed RFX75 with having to replace that capacitor is no small feat tho and I'll be estatic if it works. I messed up putting it on the radio I did thinking I had fixed the problems with it first. It has some sporadic problem I thought I had fixed but apparently didn't.
Anyway I'm pretty excited about this mod and have read really good things about it. Like JoshC. said, a little boost in receive is something all radios could use. So much emphasis is always put on boosting the transmit. Doing away with most of the noise in a radio is another huge plus imo.
I'll let you guys know how it all goes when the time comes.
Had a delay getting the parts. My card kept getting declined. Futurlec bills thru their main office in Australia and I finally figured out Australia is on my banks fraud list due to too much unchecked fraud. Had them do a 48 hour lift on the fraud ban and my parts just shipped today.
I did not see what radio you are working on with the receive upgrade.
I was looking for receive upgrade instruction for my Galaxy DX949 when I found this topic.
If not a Galaxy DX949, then what radio is this upgrade for?
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