Using Ranger Ranger With Amp

[W2VW]

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.

Fun when someone goes overboard on coupling caps and it takes off : )

It was written the Ranger was really designed as a driver for the desk Kilowatt. Makes sense to have the inverse feedback as the modulators would behave more like triodes and behave better into a load with impedance diving during 810 grid current.

[W2VW]

Hi Dave,

OK, thanks for that information. Thanks OM.

Al

You're welcome! Just a rehash of what was commonly known info within active AM operator circles plus what's in the book : )

See you on the air,

Dave

[VE3AJM]

Okay Dave.

Yes, I've known about the low power mod for a long time. I think I have a recording of Tim going through it with another guy on 40m in the archives.

If you get on down around 3725kc sometime, we'll be happy to chat with you. Last time we worked on the air, you had a different call sign and were on the air late night 75m. So its been a while.

Al

[wa3dsp]

What I did in my Ranger upgrade was solid-state it and regulate the entire low voltage bus. Before regulation under load it sits at about 340 volts. I regulate it to 300V. This could be as low as 270-280 if you wanted. The modulator screens run on the regulated LV B+ as well as the clamp tube screen.

I did not do it but if you wanted to run the modulator plates and PA plate/screen from the LV you could use the unregulated low B+ to do that. All of the low level RF and audio stages as well the modulator screen would see the regulated voltage as long as the unregulated low B+ was maintained several volts above the regulation voltage.

[WA3MJY]

I have been using my Ranger 2 to drive a SB220 amplifier for the past 3 years.I have used a T-Pad power reducer but the best performance is modifying the rig at the accessory socket as previously mentioned. This was recommended by Tim WA1HLR and by far afforded the maximum headroom and the best results.

[AB2EZ]

I have used the Ranger's low voltage B+ as the unmodulated 6146 B+ supply for my Ranger... and I am using it at the moment at my new QTH in Princeton NJ to run my Ranger at 10W carrier output. However, I also have done the following... which reduces the load on the Ranger's low voltage and high voltage  B+ supplies... and also reduces the heating inside the Ranger:

I obtained a small "control transformer". These come in various sizes... ranging from small to gigantic. I purchased a small (rated at 100 watts) transformer, new, on E-bay. It is designed to convert 480VAC to 120VAC; but I used it in reverse as a step-up transformer. [You could also purchase a suitable 100W toroidal power transformer from Antek]

I built an external DC plate supply for the Ranger's 6146 using a bridge rectifier [four 1N4007 diodes, and a pair of 100uF 450V electrolytic capacitors in series; plus a pair of 50kohm 5 watt bleeder/balancing resistors]. I plugged this into a small Variac... to produce an adjustable DC supply. The maximum voltage was roughly 600 volts under load, with the Variac set at 120VAC, and the Ranger putting out around 40 watts at carrier.

I built this supply on a small chassis, including inexpensive meters to measure the DC output voltage and the DC output current.

Using the 9-pin plug on the back of the Ranger (with suitably rated HV wire), I inserted this external DC power supply between Ranger's chassis ground and the bottom of the secondary of the modulation transformer. [Just as you would when using the low voltage B+ supply of the Ranger].

It worked great for adjusting the output of the Ranger to drive a linear amplifier.

Warning: Don't forget to put a diode [1N4007] in series with the output of this supply. If the Ranger's operate switch is moved to the "CW" position, then the Ranger's internal high voltage B+ supply will be connected to the top of the secondary of the mod transformer... and thus be connected (via the mod transformer secondary) in parallel with the output of this external supply. The series diode will prevent current from flowing out of the Ranger's internal HV B+ supply, through the mod transformer secondary, and back into this external supply.  

Stu
AB2EZ