Johnson Viking Ranger Mods

[n8fvj]

After a month, found a Johnson Ranger. I am going to rebuild this transmitter. Lots of suggestions on the internet, I suspect here is the best place to ask as there is some BS out there. I am doing the following:
6AX5GT will have 33uF on choke output. With 15HY choke AC Ripple is .7 volts.
5R4GYB with have 50uF after the new 4HY choke.
All other electrolytic caps replaced with double original value except the 6AL5 and C33.
Four paper caps replaced with polypropylene caps.
Mic input will use .02uF poly cap installed for 100Hz out using unamplified D-104 mic.
Install shielded wire from mic input to 12AX7 grid input. Shield new cap at mic input jack. Ground at jack only.
Polypropylene type .02uF cap on 12AX7 first plate and .02uF on 12AX7 second plate.
Install .001uF 3KV on audio driver xfmr out and .01uF & .001uF 3KV on mod xfmr output to stop oscillation.
Install 312 volt zener on 1614 tube screens with 10uF replacing .1uF. Adjust R35 a little higher out voltage.
Install Heyboer 50 watt mod transformer and new 4HY choke replacing 10HY choke. (Mod xfmr goes where 10Hy choke was located). This makes 100Hz @ 100% modulation. New choke and new caps has 1/2 original AC ripple with 50uF cap.
Use 6146, 6146A or 6146B tube? (update- 6146 or 6146A is ok).

What am I missing?

[Opcom]

Choice of 6146 - -some have reported instability in when switching between the plain version and the -A/-B versions in RF circuits. I don't know that radio.

Looked at the Heyboer site. No mod iron appears listed, but it does exist. They advertise a wide range of product but seem to show very little unless I'm missing the catalog or something else. I hate to have to call or write just to see product examples other than musician amplifier transformers. Have you had better success?

[n8fvj]

Ranger mod iron is Heyboer model HTS-13267. I installed one in a Ranger but sold it. I have new Ranger now.  Note- read 6146 and 6146A are identical. I purchased new 6146A.

[n8fvj]

Over 350 views and no advice. I guess I got it all.

[DMOD]

After a month, found a Johnson Ranger. I am going to rebuild this transmitter. Lots of suggestions on the internet, I suspect here is the best place to ask as there is some BS out there. I am doing the following:
6AX5GT will have 33uF on choke output. With 15HY choke AC Ripple is .7 volts.
5R4GYB with have 50uF after the new 4HY choke.
All other electrolytic caps replaced with double original value except the 6AL5.
Mic input will have resistor removed & .02uF poly cap installed for 100Hz out using unamplified D-104 mic.
Polypropylene type .02uF cap on 12AX7 first plate and .04uF on 12AX7 second plate.
Install .001uF 3KV on audio driver xfmr out and .01uF & .001uF 3KV on mod xfmr output to stop oscillation.
Install 312 volt zener on 1614 tube screens with 10uF replacing .1uF. Adjust R35 a little higher out voltage.
Install Heyboer 50 watt mod transformer and new 4HY choke replacing 10HY choke. (Mod xfmr goes where 10Hy choke was located). This makes 100Hz @ 100% modulation.
Use 6146, 6146A or 6146B tube? Does rear 9 pin octal socket need jumpers installed to operate? Shows 3 to 5, 2 to 6 and 7 to 8 on schematic.

What am I missing?

Let's start with the speech Amp Mods. If you are going to use an unamplified D-104, you need at least a 3.3M resistor at the grid of the first stage.

[n8fvj]

What am I missing?
[/quote]

Let's start with the speech Amp Mods. If you are going to use an unamplified D-104, you need at least a 3.3M resistor at the grid of the first stage.


[/quote]
Need 3.3 meg at mic input when I place a coupling capacitor in circuit at mic input? I thought the 4.7K to 1 meg is good. Original circuit does not use a coupling capacitor..

[DMOD]

What am I missing?

Let's start with the speech Amp Mods. If you are going to use an unamplified D-104, you need at least a 3.3M resistor at the grid of the first stage.

Need 3.3 meg at mic input when I place a coupling capacitor in circuit at mic input? I thought the 4.7K to 1 meg is good. Original circuit does not use a coupling capacitor.

The original design lacked a lot of things, which the mods overcome, including proper low B+
filtering.

The input cap isolates any DC appearing on the grid.

The 10k and 68pf cap form an RF filter.

A 3.3Meg grid resistor is the minimum load for an unamplified D-104 in order to get the lower frequencies you want.

The other components place the 12AX7A into the more linear amplification regions and improve articulation.

[n8fvj]

What am I missing?

Let's start with the speech Amp Mods. If you are going to use an unamplified D-104, you need at least a 3.3M resistor at the grid of the first stage.

Need 3.3 meg at mic input when I place a coupling capacitor in circuit at mic input? I thought the 4.7K to 1 meg is good. Original circuit does not use a coupling capacitor.

The original design lacked a lot of things, which the mods overcome.

The input cap isolates any DC appearing on the grid.

The 10k and 68pf cap form an RF filter.

A 3.3Meg grid resistor is the minimum load for an unamplified D-104 in order to get the lower frequencies you want.

The other components place the 12AX7A into the more linear amplification regions and improve articulation.

Modulator Screen Grid Voltage regulator;

http://amfone.net/Amforum/index.php?topic=48176.0

Is that 3.3meg in series with mic input at jack or replace resistor of 1 meg on 12AX7 tube grid with 3.3meg to ground?

[DMOD]

Is that 3.3meg in series with mic input at jack or replace resistor of 1 meg on 12AX7 tube grid with 3.3meg to ground?

As per the schematic you replace the 1 meg resistor at 12AX7 pin 2 and ground with a 3.3Meg from pin 2 to ground.

C5* is also across R17*. The new 10k and the new 0.005 is in series with the mic jack pin.

So Pin 2 of the 12AX7 has three components connected to it, the 10k, the 3.3Meg, and the C5*

[n8fvj]

Is that 3.3meg in series with mic input at jack or replace resistor of 1 meg on 12AX7 tube grid with 3.3meg to ground?

As per the schematic you replace the 1 meg resistor at 12AX7 pin 2 and ground with a 3.3Meg from pin 2 to ground.

C5* is also across R17*. The new 10k and the new 0.005 is in series with the mic jack pin.

So Pin 2 of the 12AX7 has three components connected to it, the 10k, the 3.3Meg, and the C5*

Got it. Thanks.

[n8fvj]

A few untrue internet posted Ranger mods and 'issues'.
The 6550 is a bad tube for the modulator. It's the best 600 volt & 35 watt plate tube. As close to a 6L6GC/1614.
6550 higher filament current over taxes transformer. Not, transformer has 10 amp filament rating. Use LED bulbs.
The 30uF LV capacitor is way too small. With the 15 HY choke & 30uF cap the AC ripple is only .7 volts.
Weak interstage transformer. The driver transformer is large enough for 100Hz audio.
Change C57 to .1uF. This removes too many high frequencies. Leave .02uF in place. It works to 100Hz well.
Remove C53, C56 and C-60. C53 and C56 removal does nothing. C60 removal can cause oscillation.
Change C71 from .1uF to 20uF. Leave alone unless zener regulation is installed. Then change to 10uF.
Ceramic caps as good as polypropylene type in audio chain. Not true, avoid ceramic capacitors in audio chain.
C51 and C55 at .1uF are high enough capacitance. Have to be changed anyways, use 10uF @ 450V caps, can't hurt.
Don't forget C33 10uF 450 volt replacement.
.

[DMOD]

...Change C57 to .1uF. This removes too many high frequencies. Leave .02uF in place. It works to 100Hz well.
Remove C53, C56 and C-60. C53 and C56 removal does nothing. C60 removal can cause oscillation.
Change C71 from .1uF to 20uF. Leave alone unless zener regulation is installed. Then change to 10uF.
Ceramic caps as good as polypropylene type in audio chain. Not true, avoid ceramic capacitors in audio chain.
C51 and C55 at .1uF are high enough capacitance. Have to be changed anyways, use 10uF @ 450V caps, can't hurt.
Don't forget C33 10uF 450 volt replacement.

What reference are you using for disagreement? Whose writeup?

1) Changing C57 to 0.05 or 0.1 uF increases low frequency response,

2) C53 and C56 removal increases intelligibility. If RF is filtered at front end, there is no need for these. See my schematic of speech amp modifications previously posted.,

3) Ceramic coupling caps are just fine as this is not an audiophile circuit,

4) C51 and C55 at 1.0uF are more than enough in original circuit to reduce ripple. See my schematic of speech amp modifications previously posted.

5) C33 is for RF shunting and a .005 is sufficient. You don't want a large holdup voltage on a screen at Keyup.

[n8fvj]

...Change C57 to .1uF. This removes too many high frequencies. Leave .02uF in place. It works to 100Hz well.
Remove C53, C56 and C-60. C53 and C56 removal does nothing. C60 removal can cause oscillation.
Change C71 from .1uF to 20uF. Leave alone unless zener regulation is installed. Then change to 10uF.
Ceramic caps as good as polypropylene type in audio chain. Not true, avoid ceramic capacitors in audio chain.
C51 and C55 at .1uF are high enough capacitance. Have to be changed anyways, use 10uF @ 450V caps, can't hurt.
Don't forget C33 10uF 450 volt replacement.

What reference are you using for disagreement? Whose writeup?

1) Changing C57 to 0.05 or 0.1 uF increases low frequency response,

2) C53 and C56 removal increases intelligibility. If RF is filtered at front end, there is no need for these. See my schematic of speech amp modifications previously posted.,

3) Ceramic coupling caps are just fine as this is not an audiophile circuit,

4) C51 and C55 at 1.0uF are more than enough in original circuit to reduce ripple. See my schematic of speech amp modifications previously posted.

5) C33 is for RF shunting and a .005 is sufficient. You don't want a large holdup voltage on a screen at Keyup.

W8JI agrees with my write up except the ceramic caps. In audio about everyone knows ceramic adds a lot of distortion. Why have it in the Ranger audio? Read about capacitors in audio circuits here:

https://jacmusic.com/techcorner/SBENCH-PAGES/sbench102/caps.html

[DMOD]

...Change C57 to .1uF. This removes too many high frequencies. Leave .02uF in place. It works to 100Hz well.
Remove C53, C56 and C-60. C53 and C56 removal does nothing. C60 removal can cause oscillation.
Change C71 from .1uF to 20uF. Leave alone unless zener regulation is installed. Then change to 10uF.
Ceramic caps as good as polypropylene type in audio chain. Not true, avoid ceramic capacitors in audio chain.
C51 and C55 at .1uF are high enough capacitance. Have to be changed anyways, use 10uF @ 450V caps, can't hurt.
Don't forget C33 10uF 450 volt replacement.

What reference are you using for disagreement? Whose writeup?

1) Changing C57 to 0.05 or 0.1 uF increases low frequency response,

2) C53 and C56 removal increases intelligibility. If RF is filtered at front end, there is no need for these. See my schematic of speech amp modifications previously posted.,

3) Ceramic coupling caps are just fine as this is not an audiophile circuit,

4) C51 and C55 at 1.0uF are more than enough in original circuit to reduce ripple. See my schematic of speech amp modifications previously posted.

5) C33 is for RF shunting and a .005 is sufficient. You don't want a large holdup voltage on a screen at Keyup.

W8JI agrees with my write up except the ceramic caps. In audio about everyone knows ceramic adds a lot of distortion. Why have it in the Ranger audio? Read about capacitors in audio circuits here:

https://jacmusic.com/techcorner/SBENCH-PAGES/sbench102/caps.html

My question was, whose or what write-up were you disagreeing with?

Also, notice the very apparent non-linearities associated with the ceramics. All of these are bad enough to be acoustically displeasing. The characteristics also change quite radically with frequency. It's been pointed out that sometimes, these characteristics can be used to advantage to add "crunch" to guitar amps. Because of the effect of voltage, it ought to be possible to fine tune the sound by using different voltage rated parts (assuming they are rated high enough for your amp.)

What is "acoustically displeasing" and what is "crunch?"  This is undoubtedly nontechnical, undefined BS terminology from audiophile jargon.

Which W8JI article were you referencing?

Any distortion in any circuit should be measured with a distortion analyzer. The author did not do this so he has not proven anything.

You can use any coupling cap of the correct value and voltage as you please. but can you actually detect a received signal and tell us what kind of coupling caps were used in the transmitter's speech amplifier or driver?

I think you misunderstood W8JI's comment By the way, you can use disc capacitors. It makes absolutely no difference in sound or performance if you use an orange drop or a ceramic disc in audio circuits. Save your money and time, and use whatever is handy to you.

http://www.w8ji.com/Johnson%20audio%20mods.htm

[n8fvj]

Here is his Ranger quote and it does not 100% agree with your mods, but who knows if W8Ji or you have better advice.

Remove C-53?
C53 is 200 pF in parallel with three resistances. Those resistances are the plate resistance of V7A, R19, and
R23.

200pF @ 3kHz is 265k ohms. That 265k ohm impedance is in parallel with about 50k ohms, so removing C53 would have a negligible effect. It doesn't change anything measureable. Let it alone.

Remove C-56?
Again about C56 is 470pF or 113k @ 3000Hz in parallel with the plate resistance of V7B, R23, and R27. That's 113k in
parallel with about 45K ohms. Again, not a big change in level although very slightly more effect than removing C53. Leave C53 alone, too.

Remove  C-60?
Removing this cap could destabilize the audio system! It is in the negative feedback loop. The internal Ranger audio feedback loop has negative feedback around this component. Removal of this cap won't affect response when feedback phase is negative!!

Removing this capacitor impacts frequency response and gain on frequencies where feedback is positive, such as those far above normal audio frequency ranges! Any advice to remove this part is very bad advice!!!

Change  C-52 from 500 pfd to .02 mFd
OK, this is about the only major worthwhile effect, since it will bring low frequencies up several dB. In my own rigs, I've found that a change from 500 pF to .01 uFd was far more than enough.

Change  C-51 and C-55 from .1 to 20 mFd
This is a wasteful change. This change won't do anything except reduce very low sub-audible bass slightly. The reason why is very easy to see. The impedance at the point where C51 and 55 are attached is very high compared to the reactance of the capacitor.  C51 at .1mF is 5.3k ohms reactance. The impedance at that point in the circuit to the audio path is 470k ohms. Obviously any change in voltage across C51 or C55 caused by the time-varying anode current of the 12AX7 is so miniscule the 20uF is a wasted effort. I measured only a few nanovolts of AC across C51 at 300Hz.

Change  C-57 from .02 mFd to .1 mFd
C57 is 26.5K @ 300Hz. It's in series with about 100k ohms total R (counting feedback). This reactance causes about 1.5 dB rolloff at 300Hz. Changing C57 to .1uF will increase lower end gain, but it will also unbalance overall response by about three dB or so when low end is compared to high end.

The Ranger (and Valiant) really don't require a bass gain increase beyond increasing C52! Audio response is very flat with only a change in C-52. As a matter of fact changing C-57 to a larger value creates a problem. Increasing the value of C57 causes the lows to be emphasized more than highs, and then this change forces you to go back through the rest of the circuit to boost highs just because you unbalanced the response!

Change  C-71 from .1  mfd to 20 mfd
I'm not sure of the effect of this, but my instincts tell me it has no effect.

And , as I stated ceramic is poor and posted various capacitors response on an oscilloscope, the ceramic is as bad as it gets for audio. I just have nothing more to say and I am a tube audiophile with over 30 years experience in changing out audio couplings caps. You use ceramic, I will use polypropylene, but actully prefer paper oil caps as best. Polypropylene is one step back from best, but this is a Ham radio.

[Pete, WA2CWA]

N8FVJ please be careful of posts when quoting. Your most recent post included quote - quote - quote - response was so screwed up you couldn't tell who was saying what.
I removed everything you were trying to quote and just left your message. Before you save, you can "preview" your message to see how it looks.

Posts should be "reader friendly" so that anyone who reads them, can follow along.

[n8fvj]

N8FVJ please be careful of posts when quoting. Your most recent post included quote - quote - quote - response was so screwed up you couldn't tell who was saying what.
I removed everything you were trying to quote and just left your message. Before you save, you can "preview" your message to see how it looks.

Posts should be "reader friendly" so that anyone who reads them, can follow along.

I did place a line in-between his multiple quotes and my response, but ok.

[DMOD]

...Remove  C-60?
Removing this cap could destabilize the audio system! It is in the negative feedback loop. The internal Ranger audio feedback loop has negative feedback around this component. Removal of this cap won't affect response when feedback phase is negative!!

Removing this capacitor impacts frequency response and gain on frequencies where feedback is positive, such as those far above normal audio frequency ranges! Any advice to remove this part is very bad advice!!!...

I have seen and read his exact text since I provided a link to it in post 13 which you failed to do.

C60 is across T3's secondary in the Ranger schematics I have seen and it's value is 0.005uF. It's main purpose is to reduce the frequency response at the high end of the spectrum in order to avoid excessive ringing. It is not a good snubber circuit.

BTW, I never said to remove C60 so I fail to see with whom you are arguing. Do you intend to argue or do you intend to learn something?

Now look at R27. To avoid all of this feedback crap. I disconnect the T2 secondary lead to the bottom of R27 and ground this end of R27, so the top end of R27 goes to Pins 2 and 7 of V8 and the bottom end goes to ground. I tape off that loose T2 transformer lead. That T2 secondary feedback winding has been problematic, since when it opens up, all kinds of noise (including RF) gets amplified at V8's grid and passed on to the modulator.

Anytime you have a feedback loop such as this, you can run into all kinds of problems; and as they say, create unforeseen consequences.

[n8fvj]

When you asked for link, I posted it. Fail to post link earlier is irrelevant.

C54 & C55 at 1uF per your statement. I stated 10uF, what is the difference in 1uF or 10uF? No big deal.

I never said remove C60. I did say earlier to replace with .001uF. All I posted was W8JI comments and he stated do not remove C60. Where is the argument you refer to?

I have no conclusion on the T2 feedback loop yet. I read without the feedback the 12AX7 gain is too high and audio pot cannot be used over 9am position. I read use a 12AV7 when the T2 feedback is removed.

DMOD, I have not dismissed your comments or stated you know less than W8JI.

[n8fvj]

I also found this on AMfone posted in 2015 by member Tim WA1HnyLR.
Link: https://amfone.net/Amforum/index.php?topic=38167.0

Your comments please DMOD.

Although in past modifications  the stock audio gets bulldozed and a much higher performance resistance coupled circuit is used the limiting factor is the stock modulation transformer. By changing a number of circuit component values as well as omitting various capacitors that kill the high audio frequency response, very favorable results can be had. As with all modification that I have published ALL OF THEM MUST BE DONE IN ORDER TO GET THE RESULTS!.

Do not omit any steps in the following changes to the Ranger modulator. Unwanted ultrasonic oscillations may result if all of the procedures are not followed !

Let us begin at the beginning.

* R17 1Meg Microphonium grid resistor, Change to 10-15 Meg ohms . This is necessary for using a D10-4 or other piezo-electric microphonium.

* Replace C50A ( cathode bypass cap with a 25-100Mfd 10 volt min electrolytic cap.

* Change C51 (0.1MFD decoulpling cap) with a 10-20MFD 450 Volt electrolytic cap.

* Change C52 500 pF audio coupling cap to a .005-.01Mfd 600V tubular capacitor ( Orange drop type or equiv.)  

* Remove C53 (200 Pf Mica cap)  

* Remove C 56(470Pf cap from pin 6 of V 7-b to ground).

The modifications so far are pretty straight forward. It was found that the method of application of negative feedback in the original Johnson design could not be made to provide enough negative feedback to flatten out the low frequency response curve below 120Hz. The method of introducing the negative feedback point had to be changed. Rather than apply the feedback to the grid of V8 (12AU7)   application has been moved to feed the cathode of V7-B (12AX7)  second audio stage.

DO THE FOLLOWING:

* Replace C50-B with a value similar with that used for C 50-A  (25-50MFD @10VDC min. ) The negative end of the cathode bypass cap DOES NOT GO TO CHASSIS GROUND.  

* Place a 330 ohm 1/2 watt resistor is placed in series with the negative (-) end of the cap to ground. Negative feedback is introduced at the juncture of the cap and the resistor.

* Connect a 18-22K 1/2 watt resistor from the tertiary negative feedback winding to the juncture of the 330 ohm resitor and the - end of the cathode bypass capacitor(C 50-B).

* Place a 1MFD 100 volt min. non electrolytic cap (orange drop or equiv) in parallel (across) the tertiary negative feedback winding of T2 (modulation transformer). This step is important. Without the parallel cap there will be ultrasonic audio instabilities. This method of introducing negative audio feedback if far more effective.

Back to the rest of the audio section:

* Measure  C57 (.02MFD) audio coupling cap for leakage. If there is ANY leakage , replace cap with anything from a.01-.05 MFD 600V cap ( Orange drop  or equiv)

* Change R27 (150 K  grid resistor) with a 470K-680K 1/2 watt resistor. Being that in the original schematic one end of the resistor went to the tertiary negative feedback winding. Being that the negative feedback winding is feeding the cathode of  V7-B the end of the grid resistor now is connected from grid of V8 to ground.  

* Change C59-A (15MFD cathode bypass) is replaced with a 25-100 Mfd 25 VDC min. electrolytic cap.

* Change R28( 820 ohm 1/2 watt resistor) with a 680 ohm 1-2watt resistor. The higher dissipation rating improves reliability.

* Remove C60(.005 cap)  across secondary of T-3 audio driver transformer)

* Replace with a 10-12K 1 watt resistor. This is a swamping resistor. This step must not be omitted.

At this point the speech amplifier mods are completed. Now on to the modulator itself. Dynamic stabilization of both screen and bias voltages is important!  

* Replace C59-B with a 100-300Mfd 50 volt electrolytic cap.

* After setting modulator idle current between 70-80 M a measure the bias voltage. Place a zener diode or combination of zener diodes in series with each other from the center tap of the secondary of T3 (driver transformer to ground. This will stabilize  the bias voltage.  

* Place a 10-20MFD 450 volt cap in parallel with C71(.1MFD mod screen bypass cap).

The following are capacitor removals:

C69-.02MFD-C66-C67-C68-C 83 all.002@1.6Kv Disc ceramic caps.  

The following caps to be changed are in the RF section:

* C47 & C48 (.002 Mfd @1.6Kv disc ) Replace with 470 Pf-.001 MFD @ 3Kv disc ceramic caps. These are bypass caps at base of rf plate choke.

* Change C46  (.002 MFD screen bypass) with a 470-500Pf 1Kv disc ceramic cap.          

At this point you have completed  all of the transmitter modification pertaining to the modulator and modulated stage  The last phase of modification is the power supply.


HOME STRETCH ITEMS

 The power supplies need attention. The  bias supply must be solid-stated. Use 2-1kv diodes to take place of the 6AL5 (V 13).

* Replace C90-A & B  with a 100-200MFD 150 V electrolytic..  

* Replace C78(30  MFD 450 V  LV supply filter cap) with am 100-200Mfd 450V electrolytic cap. If the Ranger is going to be operated strictly as a low power exciter, the HV filter cap (C77-10MFD@700VDC ) may be replaced with a 100-200MFD 450V electrolytic.

* If eventual full power operation is contemplated, simply use two identical capacitors in series with a 100K 2 watt resistor across each capacitor for voltage equalization.

You may want to use the Ranger with a high quality audio chain which requires line level input. Simply install an appropriate connector. A RCA connector or a 1/4 phone jack one jack on convenient location on rear of chassis. Run a length of shielded audio cable from the line level input jack to across the audio gain pot ( R21).

[w4bfs]

quite a cuss and discussion 

Timtron wrote up a lot about EFJ Ranger mods as well as the other folks mentioned here.  each writer stated importance.

I will mention 6146 and variants.  the Ranger does not have an adjustable neutrilsation circuit but rather seems to use a novel plate capacitor grounding method (my opinion).  works ok with plain 6146 maybe not so good with "improvements" made by RCA back then and suffixes added.  Collins went down a similar path with the S line about the same time

[n8fvj]

quite a cuss and discussion 

Timtron wrote up a lot about EFJ Ranger mods as well as the other folks mentioned here.  each writer stated importance.

I will mention 6146 and variants.  the Ranger does not have an adjustable neutrilsation circuit but rather seems to use a novel plate capacitor grounding method (my opinion).  works ok with plain 6146 maybe not so good with "improvements" made by RCA back then and suffixes added.  Collins went down a similar path with the S line about the same time

The 6146 and 6146A are identical except the cathode heater. 6146B is different and not a good match for the Ranger.

[Pete, WA2CWA]

I also found this on AMfone posted in 2015. Your comments please DMOD.

If you're going to re-post a post from somewhere back in time, it's important to the readers to identify the writer(poster - and it's good common courtesy) and to provide a link to the entire thread. Readers can then judge the validity of the past and current posts relative to the topic.

[Pete, WA2CWA]

quite a cuss and discussion 

Timtron wrote up a lot about EFJ Ranger mods as well as the other folks mentioned here.  each writer stated importance.

I will mention 6146 and variants.  the Ranger does not have an adjustable neutrilsation circuit but rather seems to use a novel plate capacitor grounding method (my opinion).  works ok with plain 6146 maybe not so good with "improvements" made by RCA back then and suffixes added.  Collins went down a similar path with the S line about the same time

The 6146 and 6146A are identical except the cathode heater. 6146B is different and not a good match for the Ranger.

OH!  Now I'm in trouble. I've been using a 6146B in my Ranger since the mid-90s. Seems to work fine. But, I also haven't replaced that VFO resistor that supposedly burns up and, as far as I can remember other then replacing the original 6146 (open filament), I haven't replaced any parts in my Ranger.
I guess I should keep the camera handy in case the day comes I throw the transmit switch and I "light it up". 

[n8fvj]

quite a cuss and discussion  

Timtron wrote up a lot about EFJ Ranger mods as well as the other folks mentioned here.  each writer stated importance.

I will mention 6146 and variants.  the Ranger does not have an adjustable neutrilsation circuit but rather seems to use a novel plate capacitor grounding method (my opinion).  works ok with plain 6146 maybe not so good with "improvements" made by RCA back then and suffixes added.  Collins went down a similar path with the S line about the same time

The 6146 and 6146A are identical except the cathode heater. 6146B is different and not a good match for the Ranger.

OH!  Now I'm in trouble. I've been using a 6146B in my Ranger since the mid-90s. Seems to work fine. But, I also haven't replaced that VFO resistor that supposedly burns up and, as far as I can remember other then replacing the original 6146 (open filament), I haven't replaced any parts in my Ranger.
I guess I should keep the camera handy in case the day comes I throw the transmit switch and I "light it up".  

Good to know Pete. I read on the internet no 6146B in Ranger.