BK 2040 technical help?

[KennyD]

I recently picked up a B&K 2040 signal generator and I'm looking for someone familiar with this test equipment. I have the service and operation manuals. I was going thru the alignment & testing procedure for this unit and I believe I found a problem.

With a 10 digit freq counter connected to the RF output of the generator I do not get any reading while in unmodulated CW mode or in any of the modulated ranges. However, If I connect it to a test radio and match them both to a channel I can hear a tone in the radios receive but it seems that it's not loud enough to set S9 with and almost undetectable at 1uv.

The manual says to check specific transistors and gives you the voltages to look for if you have a no CW output condition and I may have found some voltages out of spec. Does anyone have any experience with these?

 

[KennyD]

Does anyone have or use one of these 2040's?

 

[Radio Tech]

Kenny,
I would first start by checking the attenuator. It is possible that someone overloaded the 2040 with high power from an export radio. This will take out several parts on the noise generator board. Plus can burn resistors in the attenuator itself.

Also confirm that if you align both the 2040 and a test radio that it works on the selected channel. 1-1, 2-2, 3-3, ect. If it does then great, but if you set the 2040 on channel 1 and can hear that tone on multible channels on the test radio then you have a VCO problem.

Also there are 2 transistors that are the final amp for the 2040 that can go short reducing it's RF output. Q312 and Q313. These are located in the sheiled box.
A thread here I started about the 2040 with detains on the attenuator:
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[KD2GOE]

Kenny,
I would first start by checking the attenuator. It is possible that someone overloaded the 2040 with high power from an export radio. This will take out several parts on the noise generator board. Plus can burn resistors in the attenuator itself.

Also confirm that if you align both the 2040 and a test radio that it works on the selected channel. 1-1, 2-2, 3-3, ect. If it does then great, but if you set the 2040 on channel 1 and can hear that tone on multible channels on the test radio then you have a VCO problem.

Also there are 2 transistors that are the final amp for the 2040 that can go short reducing it's RF output. Q312 and Q313. These are located in the sheiled box.
A thread here I started about the 2040 with detains on the attenuator:
Login

can't even use that link you need a login and it is telling me"Sorry, registration is currently disabled."

 

[KennyD]

Yes, that forum is disabled. I did test those 2 transistors with a DMM and found the voltages at the pins to be out of spec according to the service manual. There where also others, but I'm guessing they can't all be bad and there must be something else wrong in the circuit somewhere. I will retest and /or replace those 2 you mentioned. I will also look into the attenuator as it does seem the output is low. The VCO seems to be functioning properly.

Shouldn't the CW mode produce an modulated output and show up on a frequency counter? Mine does not, no matter what channel it is on.

 

[Radio Tech]

can't even use that link you need a login and it is telling me"Sorry, registration is currently disabled."

opps, forgot aqbout that, sorry. I'll see if I can link it over to my website or start a repair thread for the 2040 here.

Yes, that forum is disabled. I did test those 2 transistors with a DMM and found the voltages at the pins to be out of spec according to the service manual. There where also others, but I'm guessing they can't all be bad and there must be something else wrong in the circuit somewhere. I will retest and /or replace those 2 you mentioned. I will also look into the attenuator as it does seem the output is low. The VCO seems to be functioning properly.

Shouldn't the CW mode produce an modulated output and show up on a frequency counter? Mine does not, no matter what channel it is on.

I have 3 of the 2040's myself. But can only read one with a frequency counter. the other 2 require a preamp inline to read. Also depends on the sensitivity of your counter.

Not sure how much of a voltage difference you are seeing on the transistors. Probably a good idea to check C371, voltage on IC317, and also the 15 and 5 volt rails.

EDIT SHOULD BE C371 NOT C317

 

[KennyD]

Q312 tests as follows
E = 1.04v should be 12.3v
B = .135v should be 11.6v
C = 5mv should be 3mv

Q313 tests as follows
E = 1.04v should be 12.3v
B = .14v should be 11.6v
C = 5mv should be 3mv

Q310 tests as follows
G = 5mv should be 13mv
D = 11.7 should be 11.8
S = .005mv should be 20mv

Q305 tests as follows
E = 2.0v should be 1.7v
B = 2.87v should be 14.1v
C = 4.5mv should be 3mv

Q304 test as follows
E = .005v should be 0
B = .015 should be .15v
C = 3.2 should be 2.5

all the voltages at the filters test fine but I did not trace them out thru the entire board. As far as checking C317, I will probably have to pull it to see if its good unless your telling me I should see a certain voltage across it?

 

[Eastside]

Hope you did not give much for it if it does not work right.......I am looking to buy a 2040....hope it works right if I shell out the bucks...wish people did not want so much for old test equipment.

I wonder which is better...the B&K 2040 or the Sencore CB-42?

 

[KennyD]

It was a fair price, altho the guy I bought it from either didn't know what he was doing with it or just flat out lied to me about it to sell it. But either way, I figure it's repairable. I picked it up along with the matching 1040 and a frequency counter for 3 bills.

 

[Radio Tech]

Q312 tests as follows
E = 1.04v should be 12.3v
B = .135v should be 11.6v
C = 5mv should be 3mv

Q313 tests as follows
E = 1.04v should be 12.3v
B = .14v should be 11.6v
C = 5mv should be 3mv

Q310 tests as follows
G = 5mv should be 13mv
D = 11.7 should be 11.8
S = .005mv should be 20mv

Q305 tests as follows
E = 2.0v should be 1.7v
B = 2.87v should be 14.1v
C = 4.5mv should be 3mv

Q304 test as follows
E = .005v should be 0
B = .015 should be .15v
C = 3.2 should be 2.5

all the voltages at the filters test fine but I did not trace them out thru the entire board. As far as checking C317, I will probably have to pull it to see if its good unless your telling me I should see a certain voltage across it?

Kenny, give me a bit to pull all this up. I believe the voltage should be around 12 volts at that cap. but I have to check first. I have a lot of notes trown about on repair of these units. And I plan on putting a lot of it on my site fordown load when I get the time to compile it. But will see if I can find that info tonight. There are a lot of these around in need of repair. The more info we can get out the better.

Hope you did not give much for it if it does not work right.......I am looking to buy a 2040....hope it works right if I shell out the bucks...wish people did not want so much for old test equipment.

I wonder which is better...the B&K 2040 or the Sencore CB-42?

About 250 is top dollar I am willing to pay for one. Thats in working condition. Most of the ones I get are about 100 bucks non working.

As fars which one is best? I like the features of the CB-42 over the 2040. It has a lot more features. But with that comes more problems. Plus with all the logic circuits in the CB-42, it is more difficult to repair. The 2040 is easier to fix, less logic, and is build more like an older CB is.

 

[Eastside]

It was a fair price, altho the guy I bought it from either didn't know what he was doing with it or just flat out lied to me about it to sell it. But either way, I figure it's repairable. I picked it up along with the matching 1040 and a frequency counter for 3 bills.

That sounds like a bargain if you can get it fixed....nice.....I have the bk 1801 freq counter.

 

[Eastside]

About 250 is top dollar I am willing to pay for one. Thats in working condition. Most of the ones I get are about 100 bucks non working.

As fars which one is best? I like the features of the CB-42 over the 2040. It has a lot more features. But with that comes more problems. Plus with all the logic circuits in the CB-42, it is more difficult to repair. The 2040 is easier to fix, less logic, and is build more like an older CB is.

Thanks for the info.....yep...the more complex...the more that can go wrong and the harder to fix....I have a line on a cb-42 but would prefer a working bk 2040.....but if a 2040 does not show up by the weekend.....I will probably drop the hammer on the cb-42.

 

[KennyD]

My counter is the 1805. I also picked up a Tektronix 2235 Oscilloscope and a Heath VTVM. I have a cobra 200GTL sitting on my bench that I need to replace the driver transistor in. I want to get this 2040 fixed for the receive alignment.

 

[Radio Tech]

That sounds like a bargain if you can get it fixed....nice.....I have the bk 1801 freq counter.

Would not run a cb shop without my trusty ole 1801. That is the best counter for cb repair. Somewhere in my arsenal of data I have a preamp for that counter. You build the pre-amp in a small metal box and use a BNC connector with a 3 inch coax added to it. Couiple the 5 volts to the counter jack and pick it off at the pre-amp. Get the end 1/2 inch from an oscilator and it picks it up. makes for a quick test to see what is running.

I have several counters but use the 1801 more then any.

Kenny sounds like you got a decent deal. the counter will bring 50 bucks no problem Seem the 1040 go for 100 to 150,. so you can say you have 100 bucks for the 2040. The price I pay for non working units.

My counter is the 1805. I also picked up a Tektronix 2235 Oscilloscope and a Heath VTVM. I have a cobra 200GTL sitting on my bench that I need to replace the driver transistor in. I want to get this 2040 fixed for the receive alignment.

I have 2 of those scopes. Plus 4 others including a Digital storage scope. I love 2235. Good scope.

 

[Eastside]

My counter is the 1805. I also picked up a Tektronix 2235 Oscilloscope and a Heath VTVM. I have a cobra 200GTL sitting on my bench that I need to replace the driver transistor in. I want to get this 2040 fixed for the receive alignment.

Nice set-up.......does it make a difference vtvm vs a dmm?