Balanced/unbalanced with a Ranger.

[W2VW]

   "Famous"?    No kidding...
 

Yeah you're famous now. Number one. Here's a salute.

[KC2TAU]

Okay,this is strange. I replaced the 68k and did a few tests. Once the rig is turned on the voltage on the screen rises up to about ~205 volts or so but then drops to about 100 volts in relatively quick fashion. The same sort of behaviour applies to the plate as well except in this case it rises to about ~310 volts or so and drops down to 220v.

In the schematic the voltage measured where R8 connects to R9(just below and to the right of the buffer tube in the schematic)is correct at about 320v. The voltage after R8 is about 100v even though I've replaced it and the new resistor reads 68k. The voltage where L5 connects to R9 is about ~220 volts once warm. I'm going to try replacing R9 and see where that gets me. It may be rising in value as voltage is applied to it. It is either that or something is loading the tube down somehow. Would it be wise for me to remove the tube and test the voltages with it removed provided I do not transmit and only stay in tune mode? Could C29,a 50pf mica,be leaky?

[WA3VJB]

For some reason I have a similar problem with an RCA ribbon mic. When using say a RE-11, EV-664, I don't experience any intrusion via RF. But when I use the ribbon mic, the audio squeals like a pig. Everything is balanced except the input on the Ranger. There it is unbalanced going into the grid of the 2nd stage of the speech amp.

I have two ribbon mics and both are more susceptible to RF than a variety of dynamic mics, using the same input and physical proximity to things.

Here, though, the SM57 (Beta) that he's got is a dynamic mic with a metal case so it should not be unusually vulnerable.

Also, and I learned this from noted AMer Dave Wanger, K3ZRF,  on your shielded balanced cable, only ground the shield at the equipment end that's receiving the audio signal.

[The Slab Bacon]

Well I'm working with what I have at the moment.

I'm running a random wire antenna with a counterpoise. The tuner sits about a foot and a half away from the window with the wires running the rest of the length to the window. I can certainly try and move this so that the tuner is *right* at the window but I would like to have that as a last resort only.

In regards to what WA1GFZ said about using a 620ohm load resistor I will most certainly try this and see what happens.

Is it really causing that much of an issue that I am running unbalanced from the output of my mixer?

This is a perplexing problem for me and when I'm perplexed I ask questions so bear with me.

If you are running an end-fed wire, you are asking for problemz! ! ! ! !

An end-fed is very difficult to tame, and unless you take special precautions you will USUALLY have RF in the shack problemz!  (been there, done that)

You need to first put the tuna right at the feed point of the antenna. (keeping it as far away from the rest of the gear as possible.) then you need a GOOD ground system tied directly to the tuning network as close as possible as possible. (A remote tuner is the best way possible to do it.) Then run coass back to the transmitter or T/R relay.

Keep in mind that an end fed inverted L is basically a Marconi type antenna and still needs to play against a good ground or ground field. If not, EVERYTHING between the antenna feedpoint and the transmitter will be hot with RF. One single conterpoise probably wont cut it. It also depends on where the feedpoint ends up being in regards to the frequency of operation. (Are you feeding it on a voltage node, a current node, or somewhere inbetween?)
Like others have said, shortening or lengthening the wire may make a big difference.

I got so fed up with trying to tame my end-fed that I said screw it and changed over to a balanced antenna and have never had a problem since! !

Just my $.02 worth! !

[KC2TAU]

I think my plan of action will be an isolation transformer,a better mixer and a balanced antenna.

What concerns me more now is this problem with the buffer circuit. I replaced both R8 and R9 in hopes of raising the plate and screen voltage on the buffer tube as they were both low at 250v plate and 70v screen when they should be 310v and 195v respectively. When I did this replacement the voltages stayed exactly the same and now my screen voltage on the multiplier tube has dropped from 98v before to 57v after which has caused my oscillator current to rise from an on spec 23ma to around 29ma.

What's strange is that the voltage where R8 and R9 meet is just fine at around ~330v but after R8 right where it connects to the screen is far too low at 70v or so. Could C27 be shorted to ground? It's getting to the point where I might just end up slowly rebuilding this transmitter,one section at a time,with new resistors and capacitors(it has been partially recapped as the micas and ceramics still remain).

[David, K3TUE]

I got so fed up with trying to tame my end-fed that I said screw it and changed over to a balanced antenna and have never had a problem since! !

+1

[The Slab Bacon]

I think my plan of action will be an isolation transformer,a better mixer and a balanced antenna.

What concerns me more now is this problem with the buffer circuit. I replaced both R8 and R9 in hopes of raising the plate and screen voltage on the buffer tube as they were both low at 250v plate and 70v screen when they should be 310v and 195v respectively. When I did this replacement the voltages stayed exactly the same and now my screen voltage on the multiplier tube has dropped from 98v before to 57v after which has caused my oscillator current to rise from an on spec 23ma to around 29ma.

What's strange is that the voltage where R8 and R9 meet is just fine at around ~330v but after R8 right where it connects to the screen is far too low at 70v or so. Could C27 be shorted to ground? It's getting to the point where I might just end up slowly rebuilding this transmitter,one section at a time,with new resistors and capacitors(it has been partially recapped as the micas and ceramics still remain).

Sounds to me like you are trying to take the long way around the block!   

My suggestion is to put up a properly fed balanced antenna. Set up a good station ground. ( A GROUND THAT IS AT RF GROUND! ! ) And send the transmitter off to someone that knows what they are doing to repair it. A Ranger is just not that complicated of a transmitter. It is just a Valiant that someone dropped in the dryer and shrunk a couple of sizes. If you are changing component values to get the operating voltages to come into line, you have another problem that you are overlooking somehow, somewhere.

You stated earlier that you audio changes if you touch the mic or get near the mic cable, that alone should tell you that everything in the shack is hot with RF.

ALSO KEEP IN MIND THAT  A DC GROUND IS NOT ALWAYS AN RF GROUND! ! ! ! ! ! ! ! !

 

[KC2TAU]

I understand that. I mentioned in my first post that I would be planning to put up a balanced antenna. Through reading these posts I've been able to better understand the situation at my station. The reason why I am changing subjects is that I feel it is better that I keep my questions confined to one thread instead of starting up multiple threads which would increase forum clutter.

In regards to sending the transmitter off to someone who "knows what they're doing" there is a problem of the facts that the people who usually do such work aren't cheap(which,at times,can be understandable depending on the amount of work/troubleshooting that must be done),shipping such a heavy item is not at all cheap and finally I would much rather figure this one out on myself. The only way one can become better at troubleshooting and repairing vintage equipment is through attempting the repairs themselves.

My instincts will tell me when I am in over my head and considering how this problem is only afflicting the buffer/multiplier circuit I feel that this is within my realm to tackle. In addition to the point about finding someone who works on this type of equipment I have a Hammarlund HQ-129X that needs some help(that I feel is outside of my comfort zone)and it took me considerable time and effort to locate someone who would lend me a hand. There simply are not that many people around where I live who work on older equipment.  

[KC2TAU]

- Accidental double post -

[W2VW]

R U sure R.F. isn't messing up your voltage measurements?

[KC2TAU]

I'm running the transmitter into a dummy load during the test procedure so I do not think RF would play a part. I did measurements on all of the tubes except those in the VFO compartment and,except for the oscillator screen and buffer plate and screen,they were all within spec.

[KC2TAU]

I've been still working away at it. I tested the voltages at each tube and here is what I've found.


Default

    I just did some voltage tests on the pins of both the oscillator and buffer and here is what I've found.

    All tests done at 3ma grid current.

    6CL6 Oscillator

    Pin 1: 1.8v standby 1.7v transmit
    Pin 2: -14.30v standby -13.90v transmit
    Pin 3: 46v standby 44.2v transmit
    Pin 4: 0v standby and transmit
    Pin 5: 0v standby and transmit
    Pin 6: 327v standby 321v transmit
    Pin 7: 0v standby and transmit
    Pin 8: 46v standby and 44.2v transmit
    Pin 9: -14.30v standby -13.90v transmit


    6CL6 Buffer:

    Pin 1: 0.85v standby 0.83v transmit
    Pin 2: -5.47v standby -5.30v transmit
    Pin 3: 105v standby 99.2v transmit
    Pin 4: 0v standby and transmit
    Pin 5: 0v standby and transmit
    Pin 6: 237v standby 227v transmit
    Pin 7: 0v standby and transmit
    Pin 8: 105v standby and 99.2v transmit
    Pin 9: -5.40v standby -5.29v transmit

[KC2TAU]

So it looks like the control grid on both 6CL6's has too much negative voltage on it. This negative voltage seems to originate from the junction of R45,R43 and C89 which is right outside of the 12AU7 keyer tube. I checked all of the voltages of the 6AL5 and 12AU7 and they're on spec. The interesting this is that at pin 7 there are 0 volts present but at the junction of R45,R43 and C89 there exists a negative voltage of about 7 volts. I'm trying to figure out where this negative voltage originates from as I need to lower it as this is where V3 receives the -1.75v needed.

[KC4VWU]

Just curious, what type/brand instrument are you using for the measurements?

[KC2TAU]

A Fluke 87 and a Simpson 260. If I get a weird voltage with one I cross check it with the other. I do know understand that both meters have a different impedance.