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Cobra 29 High Power mod with 2sc1969 transistor
- Thread starter Moleculo
- Start date
For an in-production equivalent to 2sc1969, you might want to look at the 2ST1480FP
http://www.st.com/stonline/products/literature/ds/16856/2st1480fp.pdf
It has similar specifications.
Perhaps transition frequency of 120MHz is adequate for 27MHz operation?
These days, TO-220 is not a good package. Its easier to find stock of bipolar high frequency power transistors in TO-252. Bit the 2ST1480FP is TO-220.
http://www.st.com/stonline/products/literature/ds/16856/2st1480fp.pdf
It has similar specifications.
Perhaps transition frequency of 120MHz is adequate for 27MHz operation?
These days, TO-220 is not a good package. Its easier to find stock of bipolar high frequency power transistors in TO-252. Bit the 2ST1480FP is TO-220.
Wow old post, sorry for bringing' it up again. Few questions.... just like the post above. CB20w and the eleflow versions. How do you ID correctly. There is a shop called Abel near here that has them.
Those monolythics are hard to find,,,, is there a good online source?
I've read that just upgrading electrolytic caps helps sound quality and stability . Also using high quality components with tighter tolerances.
Those monolythics are hard to find,,,, is there a good online source?
I've read that just upgrading electrolytic caps helps sound quality and stability . Also using high quality components with tighter tolerances.
for monolythics and electrolythics shop on ebay
100 PCS .22UF 50V MONOLYTHIC CERAMIC CAPACITOR, BOX#52 | eBay
Electrolytic capacitor kit for Cobra 2000GTL (PC497AB) | eBay
100 PCS .22UF 50V MONOLYTHIC CERAMIC CAPACITOR, BOX#52 | eBay
Electrolytic capacitor kit for Cobra 2000GTL (PC497AB) | eBay
What is the name of the tuning coil?
Step 4 mentions a tuning coil to remove a turn from. Which coil is this ? If you can tell me which one or how to find it then I would try this mod and post it on youtube. Also I have heard of buying a different slug and inserting it for the same result? anyone know if this works?
Step 4 mentions a tuning coil to remove a turn from. Which coil is this ? If you can tell me which one or how to find it then I would try this mod and post it on youtube. Also I have heard of buying a different slug and inserting it for the same result? anyone know if this works?
they are referring to L14. dont bother with the different tuning slug, removing a turn is the way to do it.
LC
LC
Want a treal easy super-modulation kit to turn it into a Modulator when you move the switch?
1.) Remove JP36 and clean out the holes.
2.) Install a 220-1000uf electrolytic cap(16-25VDC) with negative towards the final. leave the leads long.
3.) Attach jumpers to leads, starting with 60 ohms attach resistor to other end of leads and turn on and key into wattmeter and dummy load. Keep watching and dropping resistance until you get 4 watts deadkey with max swing.
4.) Adjust VR4 for 2.5 watts and turn off radio.
5.) Shorten leads and solder resistor across them.
6.) Install SPST switch in radio and run lines to both sides of resistor. This gibve you a choice between a 2.5watt dead key with monstrous audio to drive a box or about 8 watts or so deadkey with about 20 watts of swing in conjunction with the supertune.
All for educational purposes only.
1.) Remove JP36 and clean out the holes.
2.) Install a 220-1000uf electrolytic cap(16-25VDC) with negative towards the final. leave the leads long.
3.) Attach jumpers to leads, starting with 60 ohms attach resistor to other end of leads and turn on and key into wattmeter and dummy load. Keep watching and dropping resistance until you get 4 watts deadkey with max swing.
4.) Adjust VR4 for 2.5 watts and turn off radio.
5.) Shorten leads and solder resistor across them.
6.) Install SPST switch in radio and run lines to both sides of resistor. This gibve you a choice between a 2.5watt dead key with monstrous audio to drive a box or about 8 watts or so deadkey with about 20 watts of swing in conjunction with the supertune.
All for educational purposes only.
I notice you recommend a 2SC2314 over the OEM's normally pairing a 2SC2166 with the 2SC1969 in SSB radio's. Is this just a matter of preference or is it related to gain at operating bias and voltage? Is it just that it performs better with the other electrical properties of this chassis? When I looked at the Sanyo data sheet for it they did not give the gain at the bias and voltage combo we normally see in a CB. The graphs did not do much good either too blury from years of being copied or scaned. LOL If I remember right the gain was in the 60 at 120ma, 100 at 200ma and 160 at 320ma range 2SC2314 and the gain for the 2SC2166 has gain number's about 1/2 of the 2SC2314 but seems to produce it's gain with less bias current and more total watts out but can not handle as much input bias current. I have a Uniden PC122 clone that someone did this too and was wondering why they chose those parts. Thanks for your time! I had to turn down they had it adjusted so that it was swinging to 26 watt's I turned it down to 15 did not want the thing to destroy the transformer.
