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Adding an rfx75 to Cobra 29 XLR

Harley3315

Harley3315

Well-Known Member
Oct 22, 2015
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Anyone got any ideas for how to make this happen I know on the 29 ltds and such you tie it in at the final just
was hoping maybe someone had an idea how to pull this one off since the radio has extra channels and stuff already.
 

It can probably be done. But first someone would need to "translate" the procedure for later "29" radio models, and write directions with the exact part locations where connections get changed for the circuit board layout in the XLR model.

I'm not volunteering.

Those were made for only one model year that I know, 1978. The "XLR" models were replaced by the "GTL" models in 1979. Story was the FCC wanted a locked-out channel chip and channel selector for that model. The XLR was too easy to hack for non-legal channels. The 1979 "29GTL" radio is almost identical to the "LTD" that has been around since the mid-1980s.

73
 
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Yep I'm aware of all that Nomad this was the thought either the rfx75 to pick up some out put or mosfet conversion don't seem much info in the way of that on these old 858 non ssb rigs. My locals around here all run lower channels on am so great radio for that but not much out put for these old girls even after a full recap and changes that have been suggested like on the Honest Abe IE same radio.
If you have an idea how to do that maybe that would be a better way to go?
 
Adding a KL-203 would be a simple cost effective way to get more power.

RM Italy KL 203 Mobile Linear Amplifier (20-30 mhz)

RM KL 203 Linear Amplifier for Ham and CB
www.88radio.com www.88radio.com

If the radio transmits fine I would not do a mosfet conversion/mod. The only time that makes sense is if you have a blown final and the original finals cannot be found or cost a fortune.
 
Sadly the radio doesn't transmit I don't have any 1969s or 2166s or original 2029
left around here just mosfets.
 
AudioShockwav said:
HG is making 1969 transistors, I have used them and they work fine in standard replacement use.

73
Jeff
Click to expand...
Tried them in my 29's before with not so great results doing the standard tip120 variable power mod they seemed to go poof pretty quick.
 
AudioShockwav said:
I just recently used one in a TRC 448 to replace a 1307 for a friend and it worked fine.
With just a minor touch up it produced 18 watts on SSB with the original 1306 driver.
It was other wise a stock radio with no hot rod mods.

I got them here.

2SC1969

2SC1969, transistors, transistor
www.icamanufacturing.com www.icamanufacturing.com

73
Jeff
Click to expand...
I think they would likely work just fine in an ssb radio like that yes where we aren't doing a bunch of forward swing like on the 29's. I know the fet can handle it on the 29's which is why I was hoping someone could point me the right direction for those on this or help with adding the rfx75 would be even better!
 
There are a handful of type numbers that will serve just fine in the 29XLR. At least one of them was still being made, since Cobra 29 radios still had 2SC2078 finals all the time since the lead-free fraud kicked in 16 years ago.

Final transistors meant for AM-only radios are cheaper and more plentiful. Somebody should make a master list of type numbers.

73
 
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nomadradio said:
There are a handful of type numbers that will serve just fine in the 29XLR. At least one of them was still being made, since Cobra 29 radios still had 2SC2078 finals all the time since the lead-free fraud kicked in 16 years ago.

Final transistors meant for AM-only radios are cheaper and more plentiful. Somebody should make a master list of type numbers.

73
Click to expand...
Yeah I'm aware of that I used an hg1969 in a cobra 21xlr a few years actually and there was a ceramic cap removal or change I found trolling the net on that to change and with it and the newer 1957 driver and might have changed the predriver to 941 also. soon as I did whatever it was on the cap that radio perked right up was swing like 25 watts with the hg1969 only one I ever did that it held up in to be honest. Wish I could find it again but I haven't
 

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