Ranger made radios RT1 invasion

[Nowurtalkin222]

While you could use a heavier choke to provide more headroom, it's still just like putting a bigger Band-Aid on the problem. Changing the existing relay is not really necessary, since it's able to do two of the three switching jobs just fine. If I had one today, I would just add another small single pole relay coil in parallel with the existing relay. Lift the side of L2 that connects to R30 and the output combiner, from the board. Use the normally open contacts on the relay to supply 12 volts to the lifted side of L2, so it gets 12 volts applied only when the mic is keyed. This breaks one problematic connection, to the output RF, through the choke. However, from what I recall, you'll also want to remove L1 so that the second path back to the input side, is also disconnected.

The TS does use negative feedback on each transistor through a .1uf cap and 39 ohm resistor. This is good practice but cannot be relied upon to compensate for RF getting into the bias or a poor ground plane surface area around the PA circuit. There are very high RF currents flowing through the ground plane surface of the PC board around the transistors and output transformers. Sharing an unbroken large copper connection area between these points and all output transistors, reduces circuit inductance and provides the greatest stability. That issue in not really fixable in the TS but it's also not its weakest link.

The bias problems are fixable and if you add the relay, you should also consider some basic regulation for the bias so if it ever gets more than 13.8 volts applied, the higher bias current, doesn't force the thing into thermal runaway. Just add 1N4001 diodes across the 1.8 ohm resistors (R16 & R23) With the cathode (banded side) towards ground. Go one step further and add some thermal tracking by sticking those diodes on top of the nearest output transistor, with some thermal compound.

We can keep going... The bias voltage used here is often not enough to produce true class AB. The use of the 1.8 ohm (or 1.6 ohm) resistor is to hold that bias voltage down to a safe level. Since the vehicle electrical system can fluctuate between 12.6 and 13.8, TS had to compromise towards the low side, to put safety in front of spectral purity. Now if you feed an adjustable, regulated bias voltage into L2 through a 3 terminal regulator like the LM-317, you can remove the 1.8 ohm resistors (replaced with diodes) and precisely set the idling current with the pot connected to the 3 terminal regulator.

Make sure the pot is set for minimum voltage first and then ease it up until the desired idling current is reached. This part is critical because if you start too high, you can kill all transistors instantly. Don't even connect the output of the LM-317 regulator to L2, until you test what that voltage is first. Without the 1.6 ohm resistors, I'd be comfortable starting with a voltage around 6, before connecting to L2 and dialing up the correct idling current. That's 100 ma. of collector current, per transistor with no RF applied.

One last thing I forgot is to check the torque on all of those hex screws holding the boards, transistors, SO-239 connectors and case to the heatsink. Ones that got used in vehicles, can loosen up over time and cause havoc without any defective parts starting the problems.

Thanks for your patience with my critical comments. If that's not a deal stopper for you, I am able to answer questions.

So 1) have you done all the above mods and seen a stable, long lasting box w/o issues? Do the above procedures need to be done in all the 2 & 4 pill boxes? Was I totally off base with regard to my question about hooking up a seperate "amp keyer switch"? Don't ham amps (some) employ something like that?

 

[Shockwave]

So 1) have you done all the above mods and seen a stable, long lasting box w/o issues?

With respect to TS amps, I don't think I've gone beyond adding the dedicated relay contact and diodes since that was all it took to stop the chokes from cooking and the amp from oscillating. I have designed many amps around that LM-317 bias regulator with excellent stability and no failures due to instable bias voltage. Other members on this forum like Bob85 have contributed greatly on the use of this bias regulator and posted complete schematics of proven circuits.

Do the above procedures need to be done in all the 2 & 4 pill boxes?

Since the same 10uh chokes are used, operation at lower power levels, does become acceptable at some point. I've never seen the older two transistor models cook that choke. It only seemed to become an issue when the four transistor units where driven "well" or when the 5th driver got added. That put the L2, 10uh choke under stress. How long you key and how much carrier you use, determines the life of the choke.

Was I totally off base with regard to my question about hooking up a seperate "amp keyer switch"? Don't ham amps (some) employ something like that?

You're not off base at all. In fact, that removes all of the stress from "hot switching" the RF relay under load, when done correctly. All HF ham amps are required to be keyed externally by the exciter. There is a simple way to get any CB to do this if you use a microphone that has a receive control wire.

The black microphone receive wire is used to keep a small added relay, keyed during receive. If your radio needs the mic plugged in to receive, this relay will need to be DPDT. In that case, one set of contacts (NO) will be used to replace the radios receive control wire, that the relay now uses. The other set of contacts (NC) are used to key your amp. Because this relay is normally keyed, the functions of the contacts are reversed. Do not use the relay to key the radio, let the microphone still perform this function.

The key to how this method will always prevent a hot switch condition, relies on the way the microphone switch is mechanically designed to disengage the receiver, BEFORE the transmitter is activated. By using the relay in reverse, it forces the amplifier to key as soon as the receiver goes off and before the transmitter is keyed. It also holds the relay keyed until the radio goes back to receive. The only drawback is when power is removed from this relay (by turning the radio off), it will key your amp. If that's any problem, it can be eliminated with a switching transistor, that opens when powered down or, a second relay if you're more comfortable using them.

 

[Nowurtalkin222]

With respect to TS amps, I don't think I've gone beyond adding the dedicated relay contact and diodes since that was all it took to stop the chokes from cooking and the amp from oscillating. I have designed many amps around that LM-317 bias regulator with excellent stability and no failures due to instable bias voltage. Other members on this forum like Bob85 have contributed greatly on the use of this bias regulator and posted complete schematics of proven circuits.


Since the same 10uh chokes are used, operation at lower power levels, does become acceptable at some point. I've never seen the older two transistor models cook that choke. It only seemed to become an issue when the four transistor units where driven "well" or when the 5th driver got added. That put the L2, 10uh choke under stress. How long you key and how much carrier you use, determines the life of the choke.



You're not off base at all. In fact, that removes all of the stress from "hot switching" the RF relay under load, when done correctly. All HF ham amps are required to be keyed externally by the exciter. There is a simple way to get any CB to do this if you use a microphone that has a receive control wire.

The black microphone receive wire is used to keep a small added relay, keyed during receive. If your radio needs the mic plugged in to receive, this relay will need to be DPDT. In that case, one set of contacts (NO) will be used to replace the radios receive control wire, that the relay now uses. The other set of contacts (NC) are used to key your amp. Because this relay is normally keyed, the functions of the contacts are reversed. Do not use the relay to key the radio, let the microphone still perform this function.

The key to how this method will always prevent a hot switch condition, relies on the way the microphone switch is mechanically designed to disengage the receiver, BEFORE the transmitter is activated. By using the relay in reverse, it forces the amplifier to key as soon as the receiver goes off and before the transmitter is keyed. It also holds the relay keyed until the radio goes back to receive. The only drawback is when power is removed from this relay (by turning the radio off), it will key your amp. If that's any problem, it can be eliminated with a switching transistor, that opens when powered down or, a second relay if you're more comfortable using them.

Let's say it's not the right kind of mic or mic circuit per above explanation of how to use a mic to mitigate a hot switch issue. So going back to what I mentiined earlier (I think) can there alternatively be a simple amp relay remote switch be employed? You said all ham rigs worked that way, so isn't there a resistor or a transistor (I forget at the moment) that you can short to ground to key the relay? So couldn't say, a foot sw be added that keys the relay 1st before keying the radio and wouldn't that stop the hot switch condition?

 

[Onelasttime]

They've subbed them in place of the 520 in the superstar ss-36hp3 but only produce about 10 more watts pep. It seems they do better configured as in the rci-39/69 vhp as the output is quite higher with those. They're a relabeled mystery part, seems they're using the same technique as palomar. I ordered a dozen from a supplier just to experiment with them.

When they first arrived on the scene they were simply sanded down and weren't labeled, the more recent are labeled as RT1 but nobody has said what they really are. Pinout is the same as 520's but no spec sheet

Who cares how much power they put out. They invented linear amps for a reason. What we want is a transistor that is designed for RF production that has great gain and can take high swr's.

 

[Nowurtalkin222]

Who cares how much power they put out. They invented linear amps for a reason. What we want is a transistor that is designed for RF production that has great gain and can take high swr's.

Myself and another member here have already previously posted the identity of the RT1.

 

[Onelasttime]

People want what they want. When a product breaks, or finally wears out they just want what they already had before the failure.

Henry Ford famously claimed to know what people needed, and ignored what they want. The quote "If I asked what they want they would have said a faster horse".

Progress has a give-and-take nature. Improving on a 40 year-old design sounds good, but only if the customers will buy it.

73

People are idiots look at the crowed cluttered face on the Stryer 955 you would have to have the hands of a 12 year old girl to work the controls on that radio while driving down the road. Gota love a mobile radio that fails as a mobile radio! Likewise would love to see someone drive through Atlanta on the interstate while trying to navigate the menu on a menu driven radio like the AT-6666.

Practical radio with SSB that can be mounted in a modern 4 door car especialy Japanese or German with out mounting to the dash that can be seen and worked while driving with out taking eye's off the road! Not a pedo van or 1988 Suburban or Big Rig and not an old pick-up truck! No 4 inch meter, no talk back, no echo, no cheap feeling encoder's, no switches that feel like they are made from balsa wood and cheap plastic.

Actual transistors designed and rated for RF production!

 

[Nowurtalkin222]

People are idiots look at the crowed cluttered face on the Stryer 955 you would have to have the hands of a 12 year old girl to work the controls on that radio while driving down the road. Gota love a mobile radio that fails as a mobile radio! Likewise would love to see someone drive through Atlanta on the interstate while trying to navigate the menu on a menu driven radio like the AT-6666.

Practical radio with SSB that can be mounted in a modern 4 door car especialy Japanese or German with out mounting to the dash that can be seen and worked while driving with out taking eye's off the road! Not a pedo van or 1988 Suburban or Big Rig and not an old pick-up truck! No 4 inch meter, no talk back, no echo, no cheap feeling encoder's, no switches that feel like they are made from balsa wood and cheap plastic.

Actual transistors designed and rated for RF production!

I totally disagree re: the 955. I worked with those radios for 2 years and I think it's laid out beautifully. I had no issue whatsoever using the controls once you get used to the way its laid out. Loved it. Very easy to operate I found it. Big screen. Good angle on the screen. It tell you what is going on, on the screen when you choose something. Your not supposed to be fooling around with the buttons on a sophisticated radio like thst while driving anyway. Same as texting. Bad idea. You should never, I repeat never touch anything on a transceiver except maybe on/off/volume and/or the PTT. NO EXCUSES

 

[Handy Andy]

This is for those whom are new or trying to obtain information about RT1...

Please study this cover sheet for the IRFZ24NPBF...

See those Red arrows?​

Not to throw a lot more stuff in here to Wade thru, but please study and know that the part RT1 is proposed as being, is doomed from the start.

The typical CB generates a signal output from the Final (where this RT1 is mounted) at about 40 volts Peak-to-Peak - with some rise and fall - one of it's main limitations is the inherent - intrinsic - resistance across the junctions of the transistor - so it can only give you so much power per volt because of a Resistive element - to the output impedance the transistor has.

The RT1 has a bit less intrinsic resistance (Siemens factor) so it doesn't look like a large resistor when it's fully on, It looks more like a dead short - low ohmic impedance - low opposition to current flow and voltage drop across it's terminals.

For many this is the most ideal part to have, a switch that when you turn it on, not only can be made linear, it also is highly efficient.

There's a catch.

To attain this factor, requires it to be designed in such a way that the multi-layer sandwich the part uses to make the switch work - are thin - on top of the fact that they form a secondary part in the way the mask, layers and doping used, combine together and form.

It has a built-in function, a part often used as a form of regulation for power supplies.​

• - it also is there to protect the part from transient surges
  • - that can spike and puncture these layers making the part useless afterwards
  • - things like the reverse EMF from a Relay - can possibly damage this part.

Look at the part straddling the Drain And Source - that symbol is not arbitrary - it's real - it's a Zener

In a CB, you don't put ZENERS on the output of a radio - if you do, you'll lose the Final in the radio because of the CLAMPING action the Zener puts across the line it's used in, when its' working reverse breakdown voltage is exceeded.

And on top of that, STAYS Clamped (Engaged in operation) until all the power is removed.

If you don't understand this factor, or it's function, on the MOSFET part in question - there is part of the answer to your problem - many don't realize the NEED to keep the voltages used in radios operating with this part - stable and below a threshold - so that when an SWR tuning issue would ever occur, the part doesn't self-destruct trying to protect the 2 cent fuse

 

[Nowurtalkin222]

This is for those whom are new or trying to obtain information about RT1...

Please study this cover sheet for the IRFZ24NPBF...

View attachment 44489

See those Red arrows?​

Not to throw a lot more stuff in here to Wade thru, but please study and know that the part RT1 is proposed as being, is doomed from the start.

The typical CB generates a signal output from the Final (where this RT1 is mounted) at about 40 volts Peak-to-Peak - with some rise and fall - one of it's main limitations is the inherent - intrinsic - resistance across the junctions of the transistor - so it can only give you so much power per volt because of a Resistive element - to the output impedance the transistor has.

The RT1 has a bit less intrinsic resistance (Siemens factor) so it doesn't look like a large resistor when it's fully on, It looks more like a dead short - low ohmic impedance - low opposition to current flow and voltage drop across it's terminals.

For many this is the most ideal part to have, a switch that when you turn it on, not only can be made linear, it also is highly efficient.

There's a catch.

To attain this factor, requires it to be designed in such a way that the multi-layer sandwich the part uses to make the switch work - are thin - on top of the fact that they form a secondary part in the way the mask, layers and doping used, combine together and form.

It has a built-in function, a part often used as a form of regulation for power supplies.​

• - it also is there to protect the part from transient surges
  • - that can spike and puncture these layers making the part useless afterwards
  • - things like the reverse EMF from s Relay - can possibly damage this part.

Look at the part straddling the Drain And Source - that symbol is not arbitrary - it's real - it's a Zener

If a CB, you don't put ZENERS on the output of a radio - if you do, you'll lose the Final in the radio because of the CLAMPING action the Zener puts across the line it's used in, when its' working reverse breakdown voltage is exceeded.

And on top of that, STAYS Clamped (Engaged in operation) until all the power is removed.

If you don't understand this factor, or it's function, on the MOSFET part in question - there is part of the answer to your problem - many don't realize the NEED to keep the voltages used in radios operating with this part - stable and below a threshold - so that when an SWR tuning issue would ever occur, the part doesn't self-destruct trying to protect the 2 cent fuse

I don't know how much it matters but I think i should add...
The part you listed above has a PbF suffix. The part that I posted about here, some time ago, as being the correct usable part, as per direct word from Ranger, has a bpf suffix. Offhand I don't the difference but I know both parts exist. Someone else here, a few weeks ago, did list 2 different part numbers (per the suffix only) and showed, from the specs, that one was suitable & the other was not (and was quite different. I didn't look into that any further and I don't recall if the differences he showed were indeed between PbF & bpf, or if it was something else (that post should be in here somewhere). So, since I remembered that, I thought I should mention that it's at least possible that THE IRFZ24NPBF is what is needed to be used. And again, that part number comes directly from someone at Ranger (as being an RT1 or at least suitable).

 

[Handy Andy]

Where this gets interesting - the AGE of the suffix or when the part was produced is different.

International Rectifier merged with Infineon - so the related parts are then brought, revised - to the new corporation holdings. So naturally the merger will have problems galore until both sides are set into one.

 

[AudioShockwav]

Andy, that pdf is from 2004, and it states fifth generation .
Wonder what they are up to now?
And did they make improvements since then that might be good for switching devices, and even less desirable for rf is a good question.

73

 

[Handy Andy]

Wonder what they are up to now?

This what our problem is, every new next gen device has the profile of the parent, but the sibling it is, can operate and exhibit characteristics VASTLY different from the parent.

You raise a cautionary tale of two types of representation that anyone digging thru the Datasheets - if unaware - will run into the SAME problem under a different characteristic...

Look here, Vishay...

Ok, Non-Pb (Free) the symbol though shows a DIODE but...
NOTE THE DUT symbols and the data on the Recovery Diode...


It's still a Zener by function...
​

It's not wise to ignore the data -

What is the one MAIN thing a CB, RF amp or any transmitter uses to attain, and contain - the RF within the Tank Circuit and the Power to it...

A Coil - an Inductor...

Hence another aspect many are not looking into...

See the VDD curve?​

The inductive part of this generates a spike in both current and voltage...

The Z in the part numbering - is significant - the device is sandwiched, formed like a Zener - which means if you are running high incident voltages (like RF Audio Envelope peaks) the voltage PEP can force the device to clip, clamp and in some instances, self destruct due to the current pulsing thru the device is greater than the expected device dissipation.

Sorry, interrupted...

To add, the IAS figure of merit shows the current pulse thru the device - why is VDD 1/2 the VDS AFTER the pulse? Note it's 1/2 value during GDS the turn on to turn off holding on curve - VDD can still sink current due to the latch effect the Zener Clamping is...

There is more data in the Datasheet than what I can provide easily without lengthy response, so I recommend those looking into the IRFZ24N / PBF parts - review the data and address the power conditions you're putting this in, and work accordingly.

It may have great turn on to turn off rates and times, but the overall events you need to consider is how the device handles itself in conditions a Bipolar can work with relatively easier than the MOSFET that is replacing it - being it's own demon.

The Datasheet is attached, REV C 2016...

You think NFB was a loop that you didn't need, better think again - it can be an expensive and time consuming - mistake...

 

[Enterprise312ok]

Ok to revive this thread I blew the finals out of my lincoln 2 plus last sunday and while looking for replacements I happend uppon six star's listing for rf27zx mosfets. I purchased 10 and instaled 2.

I AM GETTING 80 PEAK ON SSB!

They are stamped Irfz24n. They work going to put one in my roadking next to see what it will do.

 

[Low_Boy]

Ok to revive this thread I blew the finals out of my lincoln 2 plus last sunday and while looking for replacements I happend uppon six star's listing for rf27zx mosfets. I purchased 10 and instaled 2.

I AM GETTING 80 PEAK ON SSB!View attachment 60550

They are stamped Irfz24n. They work going to put one in my roadking next to see what it will do.

How many watts did the radio do with I imagine 13N10 or IRF520 or what ever came in it from the factory from the factory?

 

[Enterprise312ok]

How many watts did the radio do with I imagine 13N10 or IRF520 or what ever came in it from the factory from the factory?

It did about 40 before Maybe 45. with the old finals dk on am low was 2 watts high was 15 watts, after the new finals dk on low was 15 high was 40, and it had no trouble holding that dead key. I turned down the am power but I am still putting out 80peak on ssb and 50w on fm. we will see how long they last.