Using Ranger Ranger With Amp

[w8fax]

Hello...I have some questions about using a plate modulated rig into an amplifier. I understand amplifying a CW sig and SSB or "grid" modulated AM, but I am not sure about amplifying a plate modulated sig such as a Ranger. I get the part about head room and so forth. But it seems to me that unless the signal going into the amp was pretty much perfect, all the vagaries will be amplified also. Any distortion, hum, or anything else will be there also. I know it would be with SSB also, but in my meager understanding, it seems that it would be worse when amplifying a hi level modulated signal. Am I all wet here, or does this work pretty well? I would think that an attenuator would also be a requirement, in order to fully load the Ranger and still have enuff head room in the amp. Particularly if it is one of the low drive types that are around. Thanks....AL/W8FAX

[W2VW]

The Ranger can be changed to a lower power rig by a quick change at the accessory connector.

The output will be decreased to on fourth that of a normal Ranger.

Some people insist on attenuators or reducing screen voltage. Both those schemes reduce modulator headroom and can increase distortion.

There's a lot of discussion on Ranger low power mod here which might even be found using the search feature.

Having a way to switch between low and high power makes tuning the linear AMplifier for peak output easier.

[K3ZS]

What is the quick change, is it switchable easily?

[wa3dsp]

An attenuator is a passive device just like a linear amplifier should be. One amplifies the other attenuates without changing the characteristics of the signal. Many have successfully used an attenuator to reduce the drive to the proper value for a linear amplifier. I am not saying it is the best way and it certainly is not the most efficient way but it works.

Changing the screen voltage would work also but you need to get the proper mixture of screen vs. plate modulation. There is discussion  on this here - http://amfone.net/Amforum/index.php?topic=32893.0

Running the final of the Ranger on the low voltage supply - ~300 vs. ~600 volts is a way that some have reduced the power.

You need something like 15-25 watts of AM carrier to drive most linear amplifiers to the maximum they can handle on AM. With a pair of 3-500's you could go the full legal AM limit with a pair of 572B's probably 175-200 watts. The ranger puts out about 45 watts on 75 meters. So it does not take a lot of attenuation. That's about 3-5 db. If you had an old roll of RG58 you could probably use it to get the attenuation!

Often times you here about the "audiophools" on this forum but sometimes it is the pot calling the kettle black! There are "radiophools" also. While it is important to strive for the best possible audio you can go overboard with trivialities for sure. If you have a linear amplifier in mind just load it up to about 1/4 of its SSB output to start and see how it looks on a scope and keep an eye on the heating of the tubes and transformer on prolonged transmissions. 

[W2VW]

While it is important to strive for the best possible audio you can go overboard with trivialities for sure.

Anyone can hear the difference between a Ranger with the low power mod verses factory config. Try it sometime and see.

Throwing away 6dB of dynamic headroom and then amplifying to legal limit is a great way to make friends.

Lowering screen voltage to lower input power works but requires retuning. The plate load impedance and impedance can rise very high at low power.

The low power mod does not alter tank or load impedance to the modulator. The Ranger audio feedback loop was designed with a specific modulator load impedance. So is the RF output network.

Yes EFJ made attenuators. Reminds me of new hams who think they need to buy wire antenna because somehow they must be better than homebrew.

[W2VW]

What is the quick change, is it switchable easily?

Depends on how JS one will go.

Remove the B+ feed to the final amplifier at the accessory plug, hook it to the low B+ pin at same plug and reduce mic gain.

The problem with this is the front panel meter will not measure final plate current with the mod done this way. Some run the low B+ through an external meter.

I once used a good sized open from relay internally to make the switch. Controlled it with a push-pull on/off replacement audio pot in place of the mic gain. Pull out for low power.

[Knightt150]

Hello... I have run a JOHNSON RANGER into a yaesu FL2100B for years, put a 6db pad between the RANGER and the amp load both for max power out and the rig will work great.

John W9BFO

[WA5VGO]

It seems to me that you need to load the ranger and amplifier to maximum output and then place the pad between them. Other wise, how are you going to get the additional head room you need?

Darrell

[WD5JKO]

It seems to me that you need to load the ranger and amplifier to maximum output and then place the pad between them. Other wise, how are you going to get the additional head room you need?

Darrell

    Darrell, you can certainly do that, but running everything full boar is hard on the equipment, and the voltages sag.

    I have been running my Gonset G-76 into the Gonset GSB-201 now for over a year. I use a 6 db attenuator in between the two, and I usually leave it there. Since the G-76 as tweaked can run about 140% positive peaks, it takes some special precautions so as not to overload the amplifier.

   In my case, I MUST use a scope, and when peaking the Gonset G-76 at 150 ma dipped pate current, I adjust the amp for full bore with the attenuator in place. This gives me about 200 watts or a little more. Then I re-dip the driver. Next, and here it is most critical...I advance the GSB-201 Loading control (less 'C') until the amplifier power output is down to 140 watts. Next re-peak the GSB-201 plate tune..set power to 140 again with Loading control. Now I modulate the driver and fine tune the GSB-210 loading control until the positive peaks extend to 140%. Sometimes I need to settle for 130 watts to get there.

   Oh, I never understood the Ranger folks that run the modulators on 600V and the RF at 300v. The first thing that comes to mind is the modulator P-P load impedance is cut in half..unless they dip the 6146 plate real low..not a good thing for low distortion. Then what about the negative peaks that will be violated frequently at > 100%. Sure there are things you can do, but this is a lot more then rewiring the accessory plug.

  But then again, what do I know since there is a '5' in my call letters.  

Jim
WD5JKO

[WA5VGO]

Jim,

I agree that your procedure works well. My point is, you must have the amplifier over coupled under carrier conditions in order create the headroom necessary when audio is applied. This is why the efficiency will be so poor under strictly carrier conditions. As audio is applied, the efficiency will rise.

Darrell

[W2VW]

It seems to me that you need to load the ranger and amplifier to maximum output and then place the pad between them. Other wise, how are you going to get the additional head room you need?

Darrell

   Oh, I never understood the Ranger folks that run the modulators on 600V and the RF at 300v. The first thing that comes to mind is the modulator P-P load impedance is cut in half..unless they dip the 6146 plate real low..not a good thing for low distortion. Then what about the negative peaks that will be violated frequently at > 100%. Sure there are things you can do, but this is a lot more then rewiring the accessory plug.
  

Jim
WD5JKO

A class C final will draw 1/2 the plate current when the voltage is cut in half. If it doesn't for some reason it will also make a very poor high level modulated stage.

The modulator load impedance remains the same.

[WD5JKO]

"Some people insist on attenuators or reducing screen voltage. Both those schemes reduce modulator headroom and can increase distortion."

"Throwing away 6dB of dynamic headroom and then amplifying to legal limit is a great way to make friends."

   Using an attenuator to match the peak output of a driver to be within the peak driving limit of an amplifier is a great way to minimize distortion. Sure alternatively, reducing driver peak output without an attenuator is a perfectly acceptable option as is changing an amplifier to accept higher power..such as using lower gain tubes like the 304TL in G-G.

   My pet peeve is seeing the Central Electronics collector stations that show a 100V driving a 600L linear. Here we have a 100 watt output class transmitter driving a grid driven amplifier that only needs about 8 watts drive. Sure there is a power control on the 100V, but in using it, the built in scope doesn't display much. It seems silly to use a 10-12 db attenuator here, but this works, distortion would be low, and the scope works.

   I don't like the idea of a Ranger w/o a plate meter for the 6146, nor do I like an external plate meter on the B+ line. To me, and I apparently speak alone here, having that big modulator modulating the neutered 6146 is similar to dropping a 350 Chevy into a Vega...most of those conversions ended up wrapped around a telephone pole.

Jim
WD5JKO

[W2VW]

   Using an attenuator to match the peak output of a driver to be within the peak driving limit of an amplifier is a great way to minimize distortion.
Jim
WD5JKO

That scheme only addresses distortion from the final stage being over driven or exciter anomalies arising from load other than 50 ohm j,0 like certain riceboxes.

It does not do anything for the quality of the Ranger's output which can use all the help it can get. Audio headroom is free. So is the reduced distortion. Just click the ruby slippers together. Remember, we are amplifying this signal substantially. It makes sense to keep it as clean as possible.

As for the V8 I believe they usually are hooked to a throttle of some kind.

[Tom WA3KLR]

It does not do anything for the quality of the Ranger's output which can use all the help it can get. 

I didn't realize until 2 weeks ago that the Ranger modulator has negative feedback. Imagine what it sounds like without the feedback.

[WD5JKO]

   Using an attenuator to match the peak output of a driver to be within the peak driving limit of an amplifier is a great way to minimize distortion.
Jim
WD5JKO

That scheme only addresses distortion from the final stage being over driven or exciter anomalies arising from load other than 50 ohm j,0 like certain riceboxes.

It does not do anything for the quality of the Ranger's output which can use all the help it can get. Audio headroom is free. So is the reduced distortion. Just click the ruby slippers together. Remember, we are amplifying this signal substantially. It makes sense to keep it as clean as possible.

As for the V8 I believe they usually are hooked to a throttle of some kind.

Dave, This thread is about "Using Ranger With AMP".  Many folks stumble here, and the result is severe distortion, and splatter...much worse then the driver would be by itself. I have tried to address the original post. So interfacing the two boxes, and tuning properly is important. Your right though, the stock Ranger could use help..but aren't you answering a question that wasn't asked?

A few weeks ago I was listening to 75M AM as the band went long..All those converted BC rigs were still going, but my copy was Q4 at best from all that bassy audio. Then here comes Charlie W5TOP with a stock Ranger and a D-104...barefoot...100% Q5!! They do what they were intended to do quite well.

"I didn't realize until 2 weeks ago that the Ranger modulator has negative feedback. Imagine what it sounds like without the feedback."

Tom,
 OK on the NFB on the Ranger. The Viking I had it as well..I think it was taken out of the Viking II, but I could be wrong. Johnson rigs can be fun.

Jim
WD5JKO

[W2VW]

Jim, you make some good points but go back and read the original post. It addresses minimum distortion of the signal to be amplified.

Throwing precious modulator power away should be outlawed 

[wa3dsp]

"I didn't realize until 2 weeks ago that the Ranger modulator has negative feedback. Imagine what it sounds like without the feedback."


Tom,   It sounds pretty darn good at least in my redesign. When I rebuilt my Ranger changing the mod tubes to 7027A's, and eliminating the driver transformer with a phase splitter I took out the negative feedback. The original circuit would not have made sense in my redesign anyhow. Yes it could be added back in but why argue with success. I have done the same in the Multi-Elmacs (they did not have it to begin with) and I have had very good reports with those also.

[KA2DZT]

It seems to me that you need to load the ranger and amplifier to maximum output and then place the pad between them. Other wise, how are you going to get the additional head room you need?

Darrell

  But then again, what do I know since there is a '5' in my call letters.  

Jim
WD5JKO

Glad that you were able to realize this on your own without us having to point it out to you

Fred, KA2DZT

[K3ZS]

This may seem like a dumb idea but it works.    With my AF-67 driving a GSB-101, I wired a light bulb socket mounted on a metal octagon base.   The bulb is in series and has a bypass switch.  With the light bulb attenuator in the circuit, the amp is heavily loaded past the point of peak carrier output.   I have one light bulb for 40M and one for 80M.  The AF-67 runs its full power and the amp runs its rated AM power.   The flashing light bulb adds more mystic to AM operation for visitors to the shack.

[ke7trp]

The Light bulb idea is really kind of neat.  Maybe some of those decorative filament bulbs on a wooden plank. You can get them at lowes/Homedepot now. 

I run the amp in Class C and then load the ranger to full output.  That works best for rig and amp.
 
C

[KB2WIG]

" The flashing light bulb adds more mystic to AM operation for visitors to the shack."


You need to put it inside an "ON AIR" sign.

klc

[K3ZS]

I am using a 70W bulb on 75M and a 200W clear one on 40M.   The input to my amp is untuned so these values could be different with tuned inputs.    The clear one looks like another big tube with the filament glowing.

[VE3AJM]

I have owned Rangers for years, but have never done this low power mod using the LV power supply on the final with the switch on the rear accessory plug.

I use my Ranger as the RF driver for the Johnson KW, and an outboard audio amplifier to drive the 810 grids.

Are there any known issues with the increased load that performing this mod will put on the LV transformer or choke? ie. possible overheating and failure of those components? I assume that one would also be replacing the 6AX5 rectifier tube for the LV B+, as well as beefing up the amount of filter capacity in that supply along with the other Timtron mods? I was glad to read about the step start mods posted very recently in the forum, especially as most guys will SS the power supplies.

Some guys will also use the LV B+ as the new source for modulator screen voltage, so additional loading on the LV supply. Its probably been discussed  here in the past, but I thought I would put it out there again.

Al VE3AJM

[W2VW]

I have owned Rangers for years, but have never done this low power mod using the LV power supply on the final with the switch on the rear accessory plug.

I use my Ranger as the RF driver for the Johnson KW, and an outboard audio amplifier to drive the 810 grids.

Are there any known issues with the increased load that performing this mod will put on the LV transformer or choke? ie. possible overheating and failure of those components? I assume that one would also be replacing the 6AX5 rectifier tube for the LV B+, as well as beefing up the amount of filter capacity in that supply along with the other Timtron mods? I was glad to read about the step start mods posted very recently in the forum, especially as most guys will SS the power supplies.

Some guys will also use the LV B+ as the new source for modulator screen voltage, so additional loading on the LV supply. Its probably been discussed  here in the past, but I thought I would put it out there again.

Al VE3AJM

Hi Al,

     There is an increased load on the low B+ of about 60 mills. there is also a decreased load from running the modulator at a lower output level. First rig I personally did this to is running fine over 20 years later. It was in regular use for about 5 years. Solid stated the supplies too for the record.

Dave

[VE3AJM]

Hi Dave,

OK, thanks for that information. Thanks OM.

Al