Johnson Ranger no osc current/no grid current

[W4AMV]

In the process of restoring the Johnson Ranger. Recapped the HV and LV supplies. The current problem is no grid current in TUNE mode. In addition, no OSC current. I have placed a 40 meter xtal in the XT1 position and no change. So, it appears V3 6CL6 is not operating and the screen and plate voltages are not to different, that is an issue. All the R's in the exciter section check out fine. The meter R, 3 ohm, is on the money. The buffer current does not read 40 mA at max drive however, the tube checks ok on the tester ( assume the tester is ok...). So... I am beginning to think the V3 circuit is not seeing feedback, and suspecting bad cap, either .005uF or less likely the smaller SM caps. Comments? Thanks, Alan W4AMV

[WQ9E]

Alan,
Does your Ranger have the keyer circuit (it wasn't included in early production but was added to many)?  In the VFO position can you hear the VFO spotting signal in the receiver?  A problem with the keyer tube circuit (12AU7 twin triode) could cause failure of both the VFO and XTAL oscillator.

[W4AMV]

Thanks Rodger for your reply!  No, this Ranger DOES not have the keyer circuit. The schematic I use in trouble shooting is a HYBRID of the old and new Ranger units. The SW4 wafer has been wired per the updated Ranger I to eliminate the switching of the HV, that is nice.  I have swapped both 6CL6 units between the xtal/isolator function and the buffer function. Then, I read buffer current on both tubes with max drive control. Supposed to get 40 mA, I get 20 mA for both tubes. Guess they are both poor!!, is that likely?? I am beginning to suspect that I may have a handful of .005 uF discs bypasses that are NG. They all, give or take a few, seem waxy and have blisters of waxy acne. Hi, Hi... But, I hate to pull good caps! But I may need to bite the bullet, pull a few and check them on the cap meter. Comments?  With the variac set to 110 V, after warm up, I think I may first dive in and check accurate HV and LV values. My first quick measure showed all A-ok. The HV was near 500 V at 100 V line V. I need to check LV, but I did measure the plate V of the osc. 6CL6 and it was quite reasonable, near 300 V. BUT, the screen was also near that V. So, that would make sense if the OSC is not running. Thanks! Alan

[WQ9E]

Alan,

You are welcome.  Check the resistance from pin 1 of V3 (not V2 as I originally typed, I am referring to the 6CL6 xtal oscillator tube) to ground, it sounds like L4 might be open given that your screen voltage is the same as the plate indicating no current flow in the tube.  

[W4AMV]

Well Rodger, you will like this one. I did check the L4 continuity prior and it was reasonable, about 24 ohms. The meter SH1 at 3 ohms. However, the R from pin 1 to gnd of V3 is infinite! OK, well, further checking, the PTT relay IS IN the loop! Looks like the relay added on this unit, a 6 V AC or DC, not sure, but 3-4 V at 500 mA will pull the relay ON, is in the return path of the operate SW4A switch. Upon manually closing the relay contacts I now read OSC current. So I need to understand and study what this re-wire is all about. If I try to operate the relay from an independent DC power supply, I get some BAD HUM from the Ranger. So, I suspect I have some bad 110 V ground loops here! I am still using the original 2 FUSE 2-prong 110 V plug, ugh! Have no idea what the prior user setup was like. In any case, I will review what Johnson has as the appropriate mods for putting in the PTT relay. Not sure this is wired up as they defined!

Alan

[WQ9E]

Alan,

It is often interesting (and many times maddening) what previous owners have done to gear in its 50 or 60 year history. 

At least there aren't any major component failures in your Ranger.

[W4AMV]

Hi Rodger. Well, a quick look at the wiring and it appears that the Johnson mods for PTT are correct. So the unit is to be placed in the PHONE position to operate. Then the "remote" PTT switch is pressed to operate.

Ok, so, if I follow this process, cna I go through the tune procedure in the normal manner, leave the OPeration SW in the phone position and press "PTT" to check and set osc current, buffer current, and then grid and grid drive current? For CW operation, does the unit stay in PHONE position (I would think not as I do not want the plate modulation circuit active), or do I go to CW mode and still press the PTT SW!! That seems awkward, but it is not clear in the Johnson manual, or I am missing something else. Thanks again!!  Alan

[WQ9E]

Alan,

Both my Ranger and Ranger II have the keyer circuit so they operate a little differently.  I believe you should still be able to tune up in the CW position by closing the key instead of pushing the PTT switch.  Unlike most other Johnson transmitters, the Ranger uses a non-shorting key jack.

[W4AMV]

Ok, great! And thanks again. I'll press along this evening. The bad hum I get by activating the 6 V relay with the Ranger on, is a bit disturbing. I think I will look at controlling the relay with a 110V-6V AC xmfr and dispense with the DC power supply. Somehow the GROUNDS of these 2 -items... the power supply and the Ranger, are not friendly to each other!

[WQ9E]

I wonder if the DC supply used is coupling hum via the wires running together through the mic cable?  Maybe the DC supply needs a little more filtering?  Look at the supply output preferably with a scope but otherwise with a meter set to read AC to check the amount of ripple.

Even with the wiring change it should be possible to tune the Ranger without a key by putting the VFO control into the spot position, of course this wouldn't allow tune-up on a crystal frequency.

[W4AMV]

Hi Rodger. Well, we have made progress, thanks to your prodding of the measurement of the cathode R of V3 to gnd. Put the key into the jack and things are now coming to life. Osc and VFO appear operational. Xtal Osc keys well and VFO sounds quite stable and tunes well. This despite the line V being at 70 or 80 V at this point. Again, bringing this unit up slow on VARIAC and let it burn in for a few hours. The confusion all along I guess is reading the manual of the Ranger I vs the Ranger 0. And, the use of the PTT relay vs. no relay for the tune up. With the PTT in place, things are altered a bit. You are correct in VFO ZERO the osc is there and so is the OSC current. I wish I could find the old Ranger 0 manual, although I do have the schematic. The keying in the VFO sounds ok, not perfect and little chirp but not horrible. I will not be able to judge until the Ranger is properly loaded. On the relay hum. I have grounded the Ranger chassis to the ground of the VARIAC. Still using the 2-fuse line plug. Will see if the ground arrangement helps. For now, I can press the relay contacts as required with a pencil eraser!

I'll let you know how all this works out. Alan

[W4AMV]

I am making headway, have proper grid current, buffer tune cap peaks properly and when keyed VFO sounds great, very little chirp and stable. Now, in plate current position and in phone or CW mode, NO PLATE CURRENT, NO DIP. Checked the clamper tube on tester, looks ok. Plate V is alive and well, 0.51 ohm SH4 is ok. Need to check the screen V's on clamper and I guess the 6146. I don't think I have another oversight on the SW and relay items where I have zip voltages on the final?? Comments?

[WQ9E]

This certainly sounds like a lack of screen voltage, that is what I would check first.    Maybe R15 is open?

[W4AMV]

I agree Rodger. I checked R15, it is fine. I checked a number of other R values around the clamper and the 6146, all look reasonable. Again, the PTT relay function is in the loop. It plays into where clip 6 on SW4A controls the grounding or not grounding of the screens. This seems all ok, in the phone mode, while in the CW mode, the screen resistances rise to about 50 k to ground. I'll check the SV values Monday evening after work. Maybe I have a very sour 6146.

[W4AMV]

Hi Rodger. Looks like I have a very sour 6146. Plate V is fine at 500 V, grid drive ok at 2.5 mA, screen V on key up ~ 8 V on key down 200+ V. No plate current or resonant dip. The VFO keys well and as loading is varied, I can pull the VFO slightly so there is some C coupling through the tube. But this tube seems DEAD. So, now I have to clean the shack up and see where that stash of ol' 6146's lay!!. I'll let you know.

[W4AMV]

Hi Rodger. Put in a 6146W. Still no plate current. Not sure it is a good tube either, but I suspect it is ok. So, still searching. I am being conservative on my line voltage, setting variac at about 100V. The grid drive is not excessive, but is 2.5 mA. I might be able to get it to 4 mA, but that should not be necessary, and I see no plate current movement at all. So there is another issue. I think I may turn my attention to the signal grid input, pin 5 of the 6146. The manual has no RF voltage readings or dc bias listings. If C32 the 50 pF is leaky or breaking down that might keep the output cutoff. However, the buffer V4, does tune and peak reasonably well.

Alan

[W4AMV]

This is like a running log on trouble shooting. I think the issue is the plate monitoring circuit. The plate voltage is dropping on key down. There has to be plate current, the meter reads ZIP. Well, I measured the meter shunt AT THE METER terminals. It reads about 25 ohms or so! What? The meter shunt R is on the money for SH4. So, next I need to understand why I am not seeing a small R across the meter in plate mode. I think I will put a wattmeter on the Ranger and see if Pout is there. Am I missing something, or should the R across the meter read close to the meter shunt value?

[KC2ZFA]

Am I missing something, or should the R across the meter read close to the meter shunt value?

did you make sure the meter switch is set to meter a current other than the plate current ?

Peter

[W4AMV]

Hi Peter. Yes, I have readings on buffer current, osc current, and grid current. So the meter is ok- and the switch, SW5,  is ok- except there is a "disconnect" in the plate reading mode. No pun intended, but this PM, I am going to try to get a handle on why the SH4 R is not clearly across the meter terminals. That has to be fundamental.

[WQ9E]

Where are you measuring HV?  Are all the jumpers on accessory/jumper plug X13 B properly in place?

I am not sure what is going on with the shunt measurement but if the meter is connected without the shunt it will be damaged through overload.  Make sure to clarify this problem before proceeding.

[W4AMV]

Hi Rodger. Yes, the accesory socket is wired correctly and in place. I am measuring the HV at a number of places. For example at the plate cap of the 6146, at the base of R15, and the screen V of the 6146 at pin 6 and the other side of R15. R15 is on the money. Again, the issue is I see no plate current. There is a supposed to be 0.51 ohm meter shunt SH4 across the meter in the plate Ip measurement mode. I do not see 0.51 ohms. However, again the 0.51 ohm R is a-ok. This measurement done with unit OFF, VOM across the meter.  R readings across the meter in other modes, say grid, buffer, osc, etc.. are reasonable. So... I am suspecting I have a wafer SW5 contact problem. And with the Ranger OFF, my goal now is to find out WHY. 

[KC2ZFA]

Hi Peter. Yes, I have readings on buffer current, osc current, and grid current. So the meter is ok- and the switch, SW5,  is ok- except there is a "disconnect" in the plate reading mode. No pun intended, but this PM, I am going to try to get a handle on why the SH4 R is not clearly across the meter terminals. That has to be fundamental.

When you measure the plate current shunt while the meter is set to measure
plate current then you're measuring the parallel combination of the shunt and
meter resistances. Did you measure the plate current shunt resistance with the
switch set to measure, say, grid current ?

Peter

[W4AMV]

Hi Peter. Yes, you are correct. However, the meter shunt R, SH4, I would think would dominate in that measurement. And I say that because in the other measurements as you point out, grid or buffer, osc, etc... for the most part I see the SH value associated with that measurement. For example, in the buffer mode, SH1, 3 ohms is present and in the grid current mode, SH3, 20 ohms is present and so on.

[KC2ZFA]

doh! you're right ! 

[W4AMV]

Peter, the internal R of the Johnson meter is 20 ohms.