Ranger 1 40-meter chirp problem
I have been restoring a Johnson Viking Ranger 1 and have failed in my many attempts to eliminate chirp on 40 (and above). I tore the VFO down and replaced all caps and resistors, took care of the Chernobyl resistor, installed ferrite beads on all leads going inside the VFO (except the output), replaced bypass caps from the VFO forward through the two 6CL6’s, and checked everything out in the keyer. All of electrolytics were replaced. Voltages appear normal. The 0A2 is new and the screen voltage is stable. All other tubes are in good shape.
On 80 I can use the Zero switch, put it in Tune, key the transmitter – and it stays on the same frequency and sounds clean. On 40, the frequency changes noticeably when switching between Zero, Tune and keying the transmitter. The frequency also changes when turning the Drive level, Grid tuning and PA tuning controls – even without keying the transmitter. Not so on 80 meters.
The VFO output is 4 volts peak-to-peak on 80, just 2 volts on 40. I have also noted that the waveform the on 6CL6 buffer (V3) cathode is squirrely when turning the controls mentioned above, and steady on 80.
I’d appreciate any words of wisdom out there! I want to re-experience the thrill of my high school operating days.
Thanks and 73,
AA7AU Lyle Bell
I assume that you have read and performed the "minimal changes/mods" for the
E.F. Johnson Ranger recommended by Phil Sales, AD5X ?
We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths. -- Walt Disney
First of all, tighten up all the machine screws that are in the unit. However, if the unit was factory built and not a kit then most of the connections to the chassis are going to be with rivets and not machine screws. You are going to have to either solder the tabs which are held in place by these rivets to the chassis or else use a punch and hammer to tighten them. Of course the best thing to do is to drill them out and replace with machine screws. But, this is a lot of work. Getting these connections tight is necessary because all of the grounds are made through them.
Next, there are actually 2 versions of the original Ranger (usually called "Ranger I" after the Ranger II came out). The earlier versions do not have the keying circuit which is mounted behind the front panel on the panel. There is a potentiometer mounted along with the tubes which controls the VFO keying. The setting of this control can definitely have an effect on whether or not the transmitter "chirps". Johnson came out with a field modification kit to add this keying circuit to the earlier versions. However, many operators did not update their transmitters to include the keying circuit.
One thing about the Ranger is that on the 80 meter band the 2nd harmonic of the VFO is used. On 160 meters and 80 meters the VFO operates in the 160 meter band. On 40, 20, 15, and 10 meters the VFO operates on the 40 meter band and there was a tendency for the frequency to "pull" when the VFO is operating "straight through".
There is a file on BAMA which gives some information about problems with the keying circuit:
C:\Users\Glen\AppData\Local\Temp\Ranger probs and mods.gif
There is an 18K resistor (R-3) which is located inside the VFO compartment which is the dropping resistor for the 0A2 regulator tube. This resistor was very under-rated and needs to be replaced with an 18K resistor that can handle much more power. You can access this resistor through the side panel of the VFO and don't have to remove the VFO from the chassis. Some people say to move this resistor outside of the VFO housing. Unfortunately, doing this will seriously affect the stability of the VFO. The VFO was designed with the heat generated by this resistor taken into consideration and moving it results in a much longer time frame for the VFO to come up to normal operating temperature.
Also, replace the 6AU6 VFO tube with a 6AH6 tube. This is a direct substitution and will result in an improvement in stability. You might have to "touch up" the variable capacitors for calibration because the internal capacitance of the 6AH6 is slightly different from the 6AU6. However, do NOT move the slugs in the coils because it is the capacitance that cause a possible frequency shift.
Greg, thank you for the reference to Phil's article. I must admit I have implemented some, but not all of the recommendations.
Glen, I don't really understand the concept of straight-through pull on the VFO (I am aware of the 160 and 40 VFO's, frequency multipler etc). Can you point me to reference?
The Ranger was a kit -- no rivets. It has the keyer add-on. The screws are tight and I replaced the 18K with a 10-watt (which took a while to get!) and mounted it inside as you suggested.
I will get a 6AH6 -- thinks for the lead on that one.
I don't know of any reference to the straight through versus multiplying except for the subject comes up on the various E-Mail reflectors from time to time. The fact that the Ranger tends to "chirp" on 40 meters has been discussed a number of times.
I suggest that you list your problems on the Johnson reflector, firstname.lastname@example.org . You need to sign up for this at http://mailman.qth.net/
Note that this is a completely different site from QTH.net
Another thing that helps with both the Johnson VFOs and the Heath VFOs that are of the VF-1 type (used in the DX-100 and DX-100B) is to change the 0A2 regulator tube to an 0B2. This drops the screen voltage on the VFO tube from 150 volts to 108 volts. Doing so almost always makes a noticeable improvement on the "chirp" factor and on stability.
The ranger and valiant pull frequency and chirp because of RF ground loops.
See this page: