The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

TR33 must have been change at some time for the wrong one, as NPN would be switch on all the time and RX/TX would be in conflict. I have seen the TR33 fitted in the wrong way round a few times, after the transistor as failed. I use a 2SA1282 in most radios, which use this form of RX/TX switching. A ...

His the B+ supply to the PLL and VCO free of noise and at the right voltage?

What is the voltage at Pin 8 of the PLL (IC5)?
What happens if you unhook one end of R171?

Has R104 a cold solder joint or o/c?.
Has C91 a cold solder joint or bad?

What is the voltage at Pin 10 of IC2 on channel 19?
Cold solder joint around IC2?
Is the down mix at TP 10 the right frequency?
So Pin 1 of IC2 is noisy Yes?
Is there any noise on the supply line to Pin 1 of the PLL?
Has the VCO coil L19 unstable?

If you inject 3.00 volts in to TP9 with one end of R207 unhooked, is the frequency stable and free of noise at TP10 or Pin 17 of the PLL?

Is the fault with one of the caps in the low pass filter (PD) C79, C80, or C81?

When ask for any help it is always best to give the PCB number. If the radio is working ok, I would stay with the bipolar transistors as long as you can, it makes no sense just changing them just to gain a few extra watts. I may find the info you need is on http://www.cbtricks.com/miscellaneous/fet...

The Defpom,
Bingo, we have a winner.
It was C105.
On a cap test it show just fine, but with very hi impedance moving coil meter it show just under 1 meg.

Well done Scott.

The Defpom, I did say that all voltage regulators are ok, RX/TX switching is ok, All the components C170, D72, D73, Q35, Q37, C173, R214, R213, R215, R218 are ok. ------------------------------------------------------------------------------------------------------ Timrim, Zener diode D70 is ok, Q30...

The Defpom,
The carrier level shows instable on the spectrum analyzer.
There are no component leads touching each other.
There are no cracked traces.

The DC supply is not very clean at pin 8 (IC2) when viewed on a scope.

Scott, you are getting hot.

If you think, my last post was condescending its only because you do not understand. It is no good asking what the voltage should be, as this would not help you. How would it help you if I told you the voltage was too high or to low? It would be better if can tell me the voltages and then I can hope...

It is no good just replacing a component until you have tested them, this will not help you find the fault . To find out how to test component, do a Google search that may help you. I do not wish to be rude but if you do not know what you are doing, it would be best to take the radio to so one how c...

The Defpom,
Inject a clean 4.00 volt into TP2 did not help the signal at pin 10 of IC2 it was still noisy.
L15 alignment was ok.

I advised you the components to test on my 10th November post.

The Defpom, You called this one a "Medium" level problem, you may want to change it to a "Tricky" instead Well I thought the fault was easy to sort out. I found the fault in less than 10 minutes with the aid of a scope, and the total job was 20 minutes, which included check and s...

The KEPC-225D is the PCB number, the PLL is at the front of the radio near the channel switch and will have a number like uPD2816. As the S/RF meter is not working in RX and TX, would suggest that you have a common wire broken or you have the SWR/CAL switch in the in the SWR or CAL position and not ...

Check the meter with a DVM on a diode test, and the meter should move. If the meter is ok then check you do not a cold solder joint or broken wire. If all is ok check the components, I would tell which components to check but you have not given the PCB number. It maybe a good idea to read www.radiom...

If your radio has a 2SC2166 driver then set the bias for 50mA using TP9 and TP8.
If your radio has a 2SC1969 final then set the bias for 100mA using TP9 and TP7.
Both bias are setup USB mode with no modulation in TX

The Defpom,
The fault is still there with the frequency counter unplugged from J22.

I have check out a new 158EDX and R124 is indeed 10M and JP237 100R.

I think the Sch you have is for the ETP6900010Z, which was only in production for 4 years and is now some 10 year old.

The Defpom, C99, R129, D42, D146, R130, and L47 are all ok. Lifting R126 makes no change the amount of noise at pin 2 of IC3. Scott, Thanks for pointing out my errors. I am not sure about (R124) I will need to check in a working radio. No early EPT690010Z diagram IC2 was marked with a part name (IC0...

Well this all made me chuckle. About setup using a receiver and a telephone. TP6 is only used to setup the carrier osc in SSB and only in TX mode. The AM carrier test point is TP5, which is the output of the Balance Mod IC6. Ranger has not fitted a TP6 for many years now, and you use the resistor R1...

That is why I told you it was best to check the current being drawn.

It maybe the driver has a base emitter leak but I would check R258 and D92, R258 should be 2R2 or for people in the USA 2.2 ohms.

If R258 has gone hi also change C264 and C292.

I have seen R258 go up to 70 plus ohms.

Euhara, C95, C116, and C117 are all ok. ----------------------------------------------------------------------------------------- The Defpom, The signal at pin 10 of IC2 is noisy. RA3 and D149 are ok. R140 is the correct value. ------------------------------------------------------------------------...

Ramblingman,
The 10.695 MHz crystal filter is ok.
Even if the 10.695 MHz crystal filter was bad it would not explain, why the FM TX sounds off frequency, as the crystal filter is not used in FM.

Bob,
The crystal in your radio should be just fine.
It should be a 10.24000 MHz, term I used 10.240 MHz in my last is just a general term for the 10.24000 MHz xtal.