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No replies yet? your descriptions go all over the place.
I had fun working on one of these over a year ago.
found trouble in the modulator (replaced Q67).
Then I played around on the 10-meter repeaters
up in New York state and Toronto for days
from down here.
is your main board a 011 or 015...
oh yes, yes, on the 2970. I have a broken 2970N4 here.
The extra 400 W power amp is blown up.
(aren't they all? this N4 amp set-up looks like a potential disaster!)
So bypassed this N4 amp, and now a bare 2970 here. so have the carrier down
to two watts or less and barely turn up the mic...
-- and this advice, that everyone here probably already knows,
being this is the Prepper Forum. with like-minded people here.
Us talking about emergency electrical power with a generator.
You must protect your own property, and family first!
You can't save the world and help all the...
yes, with this set up, nothing to change in the house.
most of the people I know just run generators outside and
have all these long extension cords all over the place,
running through doors and windows sealed off with towels.
and only power their fridge and a window AC.
and that video...
I never uploaded a video here yet.
and down here in southern Louisiana's hurricane and tornado
country. many people have them Generac stand-by generator
set-ups here.
but here is video from Hurricane Francine Sept. 2024
and a few years earlier after Hurricane Ida I did the same thing.
I do...
.
I wanted a little amp, with a bias circuit already in it,
and to be driven by my Cobra 148.
I checked my pile of broken amps that were given to me.
(I got that RM Italy amp working, but no bias, sucks in SSB!)
Took a look at that DYNAMO amp, and recognized the board
as the same as a PALOMAR...
yes, measured just about 2.2 V from MIC 3 to negative.
when keyed up it goes to ground.
should not mess up the 8.4 V line, or radio would not work.
I keep my display on BRT. when changing to DIM and NOR the meter
lamp does not change much, but the channel LEDs get dimmer.
and no...
and one more thing.. if the same China board.
since you are already inside soldering on this board.
another known failure point, from what I have read,
and this happened to this radio I now own.
Resistor R130 to the PLL IC. it needs to be changed to a
bigger wattage, a half watt is good...
.
been reading this post. I have my China made 148 here that had
a few things done to it before it was given to me.
It works great now. Looks like this same main board
as you are working on. So, I just took the covers off to do
some comparisons.
looks like, by the different soldering...
listen to 6850 kHz AM at nights. Liquid Radio is there,
with 10 watts of carrier. homebrew transmitter.
heard around the SE and East coast U.S.A.
He is on the air right now! ! ! !
with the "HP" it may be one of them transmitter
outputs with two IRF520's in parallel, and draws lots of current,
and the series modulation transistor gets very hot,
0015 board.
I recently got rid of My Kenwood TS-450, that has been sitting
around for 20 years, due to not being repairable. The known
"display dot issue" and "UL" in Morse Code being heard.
I believe some of the TS-950's have the same well-known dilemma.
The Carrier Board DDS ASIC's (YM66312 ??) go bad...
first thing you can do, is power the radio up, and measure
the voltage at the PLL MB8719 IC1 at pin-9 "VDD"
it should be over 8 volts. if this voltage is down to
5 to 7 volts and changing around, this is the problem.
on my radio here it went down to 4.5 volts and the PLL failed.
https://www.worldwidedx.com/threads/help-needed-for-cobra-148-nw-st.164900/page-2
read that post. it is the blue wire from that little board as pictured.
it goes to a 10 ohm resistor, to the main board. it needs to be changed to
higher wattage. that resistor fails, and the voltage to the...
hey! hold on, hold on, before you destroy another.....
I was "very quickly" given a nice looking but not working "D" radio
about 2 years ago, after asking a local about getting a CB with SSB mode.
.
.
first problem - no TX modulation, and also receive audio
was scratchy. found that newer...
yes, older rigs! I like older transistorized radios.
I have the Atlas 215x, and sometimes I check into some
vintage radio nets. I power the RF power amplifier section
and the rest of the radio in parallel with a regulated
13.8 VDC supply and use an old Cobra CB mic. I get signal
reports...
on the TDA2003. pin-3 is common ground, and also common with the backside.
no need to insulate. (usually, maybe) I was using these devices in modulators
years ago. I would just bolt it to the chassis with a light coat of heatsink
compound, since I designed it all for the chassis to be RF...
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