RCI 69 base

[nomadradio]

Fifty-Watt peaks are the very hardest I have ever seen a pair of this size switchmode MOSFET transistors run. Magnum radios from a few years back did this in part with beefed-up ground circuits. This radio does it by adding a "pre" driver transistor ahead of the driver transistor.

But 100 Watts? From two RT-1s? Color me skeptical.

73

 

[BJ radionut]

But 100 Watts? From two RT-1s? Color me skeptical.

You would know NOMAD...
However one "Dealer" says "his" Tune-up yields 130 watts PEP

 

[nomadradio]

Had one of these come through here. Just wish I could remember the power we saw from it. Can't find the repair bill. Makes me think I gave him a freebie in exchange for using it as the photo model.

Just reminds me of putting an enormous turbo on a 2-liter four-banger.

73

 

[Riverman]

how about 0-50 = (2x) power??? 50 on dial=100w
25 on dial = 50w

Well shoot, guess I’ll have to break out my multiplication tables. I needed them when getting my ham license but thought I’d be safe in CB Land without them.

 

[AudioShockwav]

Had one of these come through here. Just wish I could remember the power we saw from it. Can't find the repair bill. Makes me think I gave him a freebie in exchange for using it as the photo model.

Just reminds me of putting an enormous turbo on a 2-liter four-banger.

Just looking at the RT1 has put me off buying anymore Ranger built radios for now.
It's a crap move to sand the number off a device to hide what it is.
They should have just used the off the shelf part number and be done with it.

They are not the first, and surely not the last but it just stinks like ebay counterfeit transistors do.

73
Jeff

 

[nomadradio]

They are not the first

Eric/Magnum's ERF-2030? Max-Mod?

RM Italy's MS1307?

Palomar linears with "TX75" and "TX100" RF transistors? Those were also the model numbers on the front panel.

Solid-state Varmint amplifiers had "SSL100" transistors. Oddly enough, this was the amplifier's model number.

Some old tricks never die.

73

 

[Rogerbird1]

OK.. all the before said..
I ran across one of these, with a blown power trace to the mosfets (rail) It had 2 blown Mosfets of the 4 . from a helpful other post, I have the replacement Mosfets installed, I did all 4 with the closest switching matches.
So, now how do you set the Bias current / Voltage?
Where do you measure it.. there is no TP7,8,9 buss board..

Anyone have a place to start..?

 

[Handy Andy]

https://www.worldwidedx.com/threads/to-anyone-who-has-adjusted-the-bias-on-an-anytone-6666.258304/

It may help.

Your problem is with the jumpers and lack of ability for flexible individual adjustment.

The jumper to one section handles ALL the MOSFET's in that section.

Look at @nomadradio post showing the pre-pre-driver.

It's a Bipolar - linear device driving a set of MOSFET's in a high gain set of stages - each stage needs to be tuned/Bias set from the Finals' BACK to the one just before the Bipolar - that Bipolar is pre set - so once your carrier balance and any offsets are tuned, adjusted and set for, the bias of the rest of the stages starts at the back, adjust for your mA draw - disconnect that stages jumper, jumper the next one - set that stages' draw, and so on, disconnecting the following stage first then reapplying the mA Ammeter as the jumper for the next stage back towards the Pre-Pre-Driver

First start by pulling all those jumpers - keep the TX from engaging a signal before your ready to measure the mA draw needed.

The Final Stage, may not have a jumper - you can set it's trim using the radios own power lead input at the power connector - with all other jumpers removed - and set your mA trim between 60 to 85mA INCREASE in power draw - for the twin in TX mode and using a 50W Dummy Load installed at the antenna connector.

mA reading from TX - stable with no audio, no signal - gives you so much mA power consumption as your set baseline - I've done this both ways - using the ammeter on the power connector - and the jumpers - the Finals may be soldered in and receive power rail thru a soldered jumper wire (there are two) but it's adjustment is summed into one GATE trimmer for that stages bias - doing the mA adjust AFTER the Final mA - Adjust - use the jumper for the stage as the best and most accurate way to trim the mA reading you need to have.

So you sum in the Draw from the Finals AS A DIFFERENCE from the radios initial no jumper TX DRAW for mA - see link for a way to set your trimmer pot to not excite the Finals (all of these trimmers need to be set low) and turn them on Finals first - one at a time.

Once you understand the process - keep all trimmers in their lowest setting - then view your TX draw on the Ammeter - it's value - that is a set value baseline - you trim your Finals to 60mA to 85mA HIGHER than that setting, once set - you're done with Finals!

Then reconnect your Ammeter to the jumpers in the radio - work on Driver stage next - and keep working back using the mA draw thru the JUMPER of that stage...

Single part draw in mA in each stage should not need more that 50mA to obtain good results with any and all modes.

 

[Rogerbird1]

https://www.worldwidedx.com/threads/to-anyone-who-has-adjusted-the-bias-on-an-anytone-6666.258304/

It may help.

Your problem is with the jumpers and lack of ability for flexible individual adjustment.

The jumper to one section handles ALL the MOSFET's in that section.

Look at @nomadradio post showing the pre-pre-driver.

It's a Bipolar - linear device driving a set of MOSFET's in a high gain set of stages - each stage needs to be tuned/Bias set from the Finals' BACK to the one just before the Bipolar - that Bipolar is pre set - so once your carrier balance and any offsets are tuned, adjusted and set for, the bias of the rest of the stages starts at the back, adjust for your mA draw - disconnect that stages jumper, jumper the next one - set that stages' draw, and so on, disconnecting the following stage first then reapplying the mA Ammeter as the jumper for the next stage back towards the Pre-Pre-Driver

First start by pulling all those jumpers - keep the TX from engaging a signal before your ready to measure the mA draw needed.

The Final Stage, may not have a jumper - you can set it's trim using the radios own power lead input at the power connector - with all other jumpers removed - and set your mA trim between 60 to 85mA INCREASE in power draw - for the twin in TX mode and using a 50W Dummy Load installed at the antenna connector.

mA reading from TX - stable with no audio, no signal - gives you so much mA power consumption as your set baseline - I've done this both ways - using the ammeter on the power connector - and the jumpers - the Finals may be soldered in and receive power rail thru a soldered jumper wire (there are two) but it's adjustment is summed into one GATE trimmer for that stages bias - doing the mA adjust AFTER the Final mA - Adjust - use the jumper for the stage as the best and most accurate way to trim the mA reading you need to have.

So you sum in the Draw from the Finals AS A DIFFERENCE from the radios initial no jumper TX DRAW for mA - see link for a way to set your trimmer pot to not excite the Finals (all of these trimmers need to be set low) and turn them on Finals first - one at a time.

Once you understand the process - keep all trimmers in their lowest setting - then view your TX draw on the Ammeter - it's value - that is a set value baseline - you trim your Finals to 60mA to 85mA HIGHER than that setting, once set - you're done with Finals!

Then reconnect your Ammeter to the jumpers in the radio - work on Driver stage next - and keep working back using the mA draw thru the JUMPER of that stage...

Single part draw in mA in each stage should not need more that 50mA to obtain good results with any and all modes.

I am gonna have to read that through a few times..
The pre-driver and driver are both RT1s. The voltage to these are controlled by the RF Power control through the 2SB827Q power transistor, the 2 output RF1s are at 13.8v.
I can only assume someone cranked up VR10 (its maxed right now), which is probably why the outputs popped..
I will need to figure out which jumpers to pull. and I just now noticed there is a TP8 with a jumper cap on it.

 

[Handy Andy]

Which is why the process to retrim the Finals needs to be done as the first step.

Because of the LACK of a jumper - the current demand and efficiency suffers, so they SOLDERED them with solid wire jumpers for the Finals. they're in your shots above.

You don't need to "unsolder" them, just pull all the other jumpers and set idle current with the timmers - all of them, turned down - you'll need to probe Gate voltage to see which way to trim them,

OR

This is why it matters...

This is NOT your board,
Close but no; it's not...
For Demonstration only!
​

If you're knowledgeable about the construction of the trimmers, look at the foil trace underneath the trimmers, it should tell you which side of the fixed part of the pots feed into - and exit from the trimmers either variable and opposite side, or straight fixed to variable - knowing which side - you turn the trimmer the opposite way to force the substrate to maximum resistance across to the wiper (variable)

Once all the trimmers are turned (set) to turn off gate voltages, the idle current for the finals can be set .- simply by keying up the radio and adjust per the test jig of ammeter at the power cord input positive lead and jumper to power connector positive.

The TX mode will draw some current - in mA - you set the Ammeter to measure first at 2A to make sure you don't blow the meters fuse if there is something soldered wrong. Then turn meter to show mA reading to see the initial draw, and you set your Final trimmer to 60 to 85mA above that figure - then once set - you can use the jumper headers of the stages for the rest of the adjustments.

If you trust your work - you can stop here and don't need to reset all the stages mA draws - that is your call.

But I wouldn't - for what ever surge or catastrophic impact caused this, you might want to double check each stages' operation to make sure they didn't, won't, and don't, destroy that work you just did.

 

[Rogerbird1]

Thanks, the method is understandable.
As the pictures show , there is one Bias pot for the final stage and one for the driver stage. I understand the method of monitoring the radio's input current with the jumper[JP8] pulled, and start with both Bias trimmers at full resistance. VR10's wiper connects to a 47ohm resistor which connects to both of the final Gates. Full clockwise (with the stops) is full ohms.
I will need to check the trimmers, not sure if they have burns on them..
I think they are supposed to be 1k and they are measuring about 300 - 350 ohms..
the markings are '1 3' ..

Thanks again,
Roger

 

[Rogerbird1]

Well, I finally got brave enough to try this.
I found an Isolation transformer with variable power and a current meter.
(Sencore PR570). Unfortunately the Amp meter only reads 2 decimal places.
I will probably have to use an external meter to get this right.

But, I took a shot, and hit a wall.
With the jumper (JP8) removed, and the replaced Bias 1k trim pots, I have and idle current of 0.13A . the TX current is 0.15A.
Since adding 55mA would be 0.1555A, I guessed at a midrange Cal point between 0.15 and 0.16A - Just as a test before making a better measurement jig.

Then I measured the mA on the jumper pins of JP8 for the drivers -- I am getting no measurable mA reading. With jumper 8 installed I am getting no output power.

So, I am stumped. It is possible i missed an open component in the predriver stage.
I am reading 4.8v on JP8.

I am truly not a fan of this design.

Roger

 

[nomadradio]

I am truly not a fan of this design.

Sometimes a customer will ask "Is this a good radio?"

I'll reply "Good for you? Or good for me? If it's good for me, that's not so good for you."

The total disconnect between the people who make it and those who sell it has brought us firestarters, (98VHP), junior firestarters (2995DX) and now this radio with sideband transmit that sounds like you're gargling, not talking.

Both radios this model I've seen so far were new, and I left the bias trimpots alone. I count four IRF520/RT1s. And two trimpots.

I'll guess the predriver has no trimpot at all. The one nearest the driver is for that stage, and the one between the two finals controls them together.

Simple method to judge idle current in SSB transmit would be to unhook the center pin of the modulator transistor. Clip the positive side of your 10-Amp meter to the loose center pin, and the negative to a wire jumper leading away from that center-pin foil pad.

Key the mike in SSB with the mike gain at zero, then turn each trimpot to its minimum-current extreme.

Best to set final bias first, before the driver can "leak" any carrier and skew the final reading. So long as the Vth of the two finals are a close match, this is probably good enough. But never dare to put two unmatched finals into this radio. Like playing russian roulette but with five chambers full and only one empty. Too many chances to be a winner.

I would not recommend more than 50 or 60 mA increase in the current reading turning up the final trimpot. And about half that much higher on the meter when the driver trimpot is advanced. Can't read finals and driver separately, but setting finals first, and adding the driver current to that reading should serve as well as having separate wires with separate current readings.

Gives you the impression they would rather you not extend the life of the radio and crimp their replacement sales volume.


73

 

[Handy Andy]

What I would have done,

Removed all the Finals and then try to determine the fault.

That "fault" may be what you're having issues with now.

The simple take apart and replace of older days doesn't truly work well with these designs.

The problems - there are several - lie in the multiple layer traces as well as marginal wattage-rated parts.

I'd just remove the finals first, power it up - leave JP8 out - then VERIFY each gate gets an Adjustable drive voltage - set it (all gates votlages) to minimum after you're done - if you miss this step - you might find a trace and several finals blown on power up.

Then Put JP8 in to test, with all Finals removed - are the gates stable and adjustable or did one just rise up? That's the question.

A blown trace - open gate - is just as bad as shorted, no voltage to one, makes you think the other three are also too low and need to be pushed upwards - there lies one condition - set for mA and if not enough - you keep setting for more - that's is why we set up to "idle" on SSB no mod first - just trying to find gate voltages - with the Finals empty.

When you install all the same, the job is easier, for all parts are sourced and gated the same hopefully from the same lot and bin so they are all within the ballpark of turn on.

Once the cause can be determined and repaired, then the install and adjust by power supply current draw is pretty straightforward.

 

[Rogerbird1]

What I would have done,

Removed all the Finals and then try to determine the fault.

I'd just remove the finals first, power it up - leave JP8 out - then VERIFY each gate gets an Adjustable drive voltage - set it (all gates votlages) to minimum after you're done

Then Put JP8 in to test, with all Finals removed - are the gates stable and adjustable or did one just rise up? That's the question.

.

By "adjustable drive voltage.." Do you mean changeable by the bias controls? if so, when you say set all to minimum - meaning no gate voltage - then install JP8 and see if any of the gate voltage rises. Basically the gate pins without the transistors installed should not change. If one changes, there is an issue with that part of the circuit.

Am I following this correctly?

Thanks for your input, and help.