B&K E-200D signal generator - no signal

Look for problems associated with the oscillator (Q1), buffer amp (2), modulator (Q3), or the attenuator network. When you say that the crystal calibrator seems to work, how are you determining this?

--
Dave M
MasonDG44 at comcast dot net  (Just subsitute the appropriate characters in 
the address)

Never take a laxative and a sleeping pill at the same time!!

Kim, thanks for your detailed info! I will start taking a closer look at those PS resistors you mention, and the electrolytics (I didn't see any obvious signs of leakage them , but it probably wouldn't hurt to replace them anyway). Her is a good site with more info on alignment, mods etc:

Mine seems to be working okay now (after replacing Q3) using the CW setting.

The manual including schematic is available here: ftp://bama.sbc.edu/downloads/b&k/e200d/

Check the power supply. The PCB board etchings on the unit I have show

10.6V & 10.0V as the two B+ supply voltages. The schematic shows 10V & 9V. After I got mine working I found the schematic voltages were more correct. I get 9.93V at the 10V point & 8.82V at the 9V point.

Here is a snippet of PS in ASCII (use fixed pitch font):

Transformer +-------->(+10V) Pri. Sec. | ):+----|>|-+---+--68R--+--47R--+->(+9V) ):( 14.0R | | 200mW | 23mW | ):+-+ | | | | ):( |15.6R | 200uF ZD 200uF ):+-|--|>|-+ 25V 10V 25V | | | | _|_ _|_ _|_ _|_

The transformer secondary measures 14-15 ohms on each side to Gnd.

Both resistors (68R & 47R) had drifted with age. The 68R going to

95ohms. I replaced both resistors. The 68R should be at least 1/2W, the 47R could be 1/4W.

Actually I started off replacing all the electrolytics & these two resistors. There are 9 electrolytics, 7 on the bottom PCB, one on the meter, & one inside the top osc. section.

The following is from my notes:

Color C# uF V Schematic replacement

----------------------------------------------------------------- Gray - C31 -200uF,25V 220/??V 220uF,35V Gray - C32 -200uF,25V 220/??V 470uF,16V

Gray - C30 - 47uF,10V 50/??V 47uF,16V Gray - C33 - 47uF,10V 50/??V 47uF,16V Gray - C34 - 47uF,10V 50/??V 47uF,16V

Blk - C28 - 10uF,25V 10/??V 10uF,25V Blk - C40 - 10uF,25V 10/??V 10uF,25V

On the meter: Gray - C55 - 47uF,50V 50/25V 47uF,50V

In the OSC (top, shielded PCB): Gray - C13 -100uF,12V 100/??V (2ea.,paralleled) 47,10V

Here is the location of most devices on the main (bottom) PCB:

+-------------------------------------------------------------+ | - | | C33 | | + 47uF | | C34 10V | | 47uF + | | 10V | | - | | | | | | - | | C28 | | 10uF | | x 25V | | 4 + | | 7 | | -200uF,25V+ R | | - x | | C40 x68Rx + | | 10uF -200uF,25V+ C30 | | 25V 47uF | | + 10V | | - | +-------------------------------------------------------------+

After replacing the above everything was working pretty well.... The internal audio osc. was not working. I had to tweak R42 (1K pot) to get any tone, then set it to 400Hz.

The above got mine back to what seems to be OEM status. Everything seems to work properly. I'm not sure of the output levels on each band as I have no way of checking RF levels accurately. All the resistors in the attenuator section were very close to perfect (still within 5%)!

If you have problems after getting rid of obvious defects the schematic has voltage levels that should be close.

One other note: The 1MHz marker is xtal controlled & the 100KHz marker is calibrated to the xtal marker. It seems the OEM PCB layout & silkscreening had both the markers running full time (for stability) & their outputs were switched in as needed. This extra noise probably caused unexpected "birdies" at the output even when the marker outputs were not switched in (markers not shielded). The wiring on my unit reflects changes (as does the schematic) that disconnects power to both marker oscillators except when they are switched in. All this is no problem except the PCB silkscreening does not match component placement is the marker area. I only found this out when I added a trimmer cap in series with the

1MHz xtal to set it more exactly at 1,000,00x Hz (haha - If my freq counter is still relatively accurate). I started with a 8-50pF trimmer & could get 1,000,00x Hz only at the 50pF setting. Adding a 15pF in parallel with the 8-50pF trimmer allowed a nice adjustment range about +60/-40Hz (999,960-1,000,060Hz).

When I got this unit the meter was 1/3 full of water :) It had been rained on!! It had not been outside long (I think just rain 1 time) but it is fine now. Good luck Kim Clay

PS: There are five internal pots shown below. The only one I know about is R42, the audio osc. pot (sets audio freq). If anyone has info on setting the others I would like to know - thanks! kc

Internal Pots: not externally adjustable; R42 - 1K - "Audio Osc." - 400Hz bridged "T" osc freq setting. R54 - 10K - "Mod Cal" per schematic.

Internal Pots: externally adjustable via holes in back chassis (facing back, Left-to-Right); R28 - 30K, Mixer Adjust R50 - 50K, "RF Threshold" R48 - 1K, "Carrier Cal"

Thanks for the link. He has some good info...

From your other post you mentioned "Not sure the 400hz tone is working when setting the switch to that setting...". Perhaps a slight tweak of R42 (1K pot) will bring it to life as that worked with my unit.

I was studying his 1 KHz mod pic at

& noticed R43, 620R in the pic. That is the correct value per the schematic. My unit has a 470R installed in that location. A close look at "R43" & "620" on the schematic shows it to be noticeably different lettering than the others. Its a small change I may make at some time.

Further studying the pics at this site reveals two different units are pictured in the modifications. The Changing the Modulation Frequency to 1KHz Disassembly Instructions E-200D Alignment Procedure pages all appear to use the same unit, s/n "27-05827"

The Adding an Output for a Frequency Counter page uses a later unit with s/n "27-13815"

My unit has s/n "27-01744", indicating a very early unit. Meter has a date code "7404" on a sliver tag. The two units shown on the mods pages have a date code stenciled on the meter (that I can't read). It seems that by s/n "27-05827" (the unit pictured on the 1 KHz mod page) they were using a new PCB with white stenciling instead of black on my earlier model. They must have also changed the pcb layout in the 1MHz & 100KHz area because the "Xtal Calibrator" switch has Blue & Gray wires where mine has resistors going to a add-on terminal strip & then on to the PCB with Blue & Gray wires.

Also my line bypass caps are 10nF where the schematic shows 1nF. Both units pictured have much smaller size cap at these locations.

Most of this data is just for archive use on Google. I had just finished restoring my unit when I found your original post. Cover/case is not even installed yet. :)

Kim

Kim, I will check the serial numbers etc on my unit and let you know what it is - I was able to get the 400khz working (it turned out that Q9 was bad) - My next problem though is the "Fine attenuator"... when checking the signal, adjusting this seems to shift the freq, but I don't think its adding more attenuation. So, more troubleshooting to do! I'll keep you posted. Mike

The fine attenuator control should not affect the oscillator frequency. If it does, then you possibly have a power supply regulation/filtering problem. Or, possibly an attempted modification or repair of the unit that has changed the circuit.

The power supply components to suspect are: C31, C32 (220uF each) D6 (10V/1W Zener) R35 (68 ohms) R36 (47 ohms) D4, D5 1N4005

Do you have a manual for the unit? If not, I can email a PDF copy to you ( about 4.5 Mb). It will save you lots of time if you have any troubleshooting abilities.

-- Dave M MasonDG44 at comcast dot net (Just subsitute the appropriate characters in the address)

I have checked the power supply and the voltage levels (10v, 9v) are okay - a scope on the 10v line looks clean to me, the 9v line seems to have a little ripple. Could that cause the freq drift in adjusting the Fine Attenuator knob? I checked the rf level and the attenuator is doing its job of adding attenuation, it just that it also moves the signal around a little as you change it. The only other thing that looks fishy to me are some of the voltages associated with the Q3 modulator (which I replaced). The base according to the schematic should be 2V, I am getting 3.6v. The emitter should be 1.3, I am getting 2.86. The collector looks okay at 8.6v (schem shows 8.8).

Mike

If the 10V supply has low 120Hz ripple the 9V supply should be even less. Probably is OK. If in doubt try bridging the PS filter caps with

100-220uF & see if it decreases lots.

No - see below...

& from a previous post...

Quote from pdf - "Operating-Instructions":

"Note - Set the output level before setting the frequency. Although the oscillator and attenuator are isolated by an emitter follower, slight frequency pulling can occur when the FINE ATTENUATOR is adjusted or step attenuators are switched in and out"

An example: On band "D" set the freq to 10MHz. Turn on the 1MHz xtal calibrator. Adjust freq setting for zero beat. Slight movement of the Fine Attenuator, in either direction, will produce a tone. A _very_ small tweak of the freq knob will again zero beat.

The b-e voltage stays the same at ~0.7V.

The schematic shows 1.3V on the emitter of Q3. You have 2.86V. Checking my unit I find 2.85V... hmmmm....

Emitter resistor is 330R (on all normal freq bands A-E). Mine measures 341 ohms (close enough).

I pulled both the DC base bias resistors to Q3, R14 & R16.

R14, 9.1K has drifted to 9.85K R16, 6.8K has drifted to 7.95K

I replace both with correct values per the schematic (within 1%).

On power up, after a 5 minute warm-up I am back to the _same_ emitter voltage, 2.85v!

I do not know if Q3 has been replaced at some time. Q3 is a 2N3440, date code 7615.

I found a 7347 date code on the main, dual section variable-cap & the meter has 7404.

So either the tuning cap & meter were >2 years old when the transistor was mfg. or Q3 has been replaced.

After all this it still functions the same. Everything seems to work & is relatively stable. Good enough for me :)

Kim

Kim thanks - I should have read the instructions! I had another user of a

200D tell me the same thing, that adjusting the fine attenuator will pull the freq around a little

Since you are getting similiar voltage readings around Q3 I don't think I will worry about that either.

I used it the other day to align a receiver on a QRP rig I have and it worked great. So I am happy with it, thaks for all of the help. Mike