Anyone have any ideas how I could clean out the inside of my radio?

[Techie7]

I would agree with Ericgibbs. Better do not disturb oldies..and vacuum cleaner will suck up them all

 

[JimB]

Now I am trying to get it set back up, but can only get ~50 watts or so out, and thats with the Mic Gain all the way up, making the IC current 250+ mA. That doesn't seem right to me.

Under what conditions were you measuring the power?
Set to TUNE to give a steady carrier, or speech?
Speech will always read about half the true current/power, if that.

What were you using to measure the power? do you know if it is accurate?

The radio could have deteriorated while unused, capacitor values changed putting it off tune.
Could be dirty contacts in the antenna c/o relay.
(On second thoughts unlikely as the voltages would be high enough to burn through the dirt I guess).

JimB

 

[Andy1845c]

Well, in the TUNE mode, going through the procedure outlined in the manual, I can't get much power out. If I fiddle with my antenna tuner, I can get a good match, close to perfect, but not alot of forward power, if I crank the mic gain way up, I get around 50 watts or so, but the "IC" current is too high.

With the mic gain at a more normal level, and the mode back on SSB, I have to pretty much yell, or whistle into the mic to even make the needles twitch. I have tried 3 different mics, so I am pretty sure thats not the issue.

I am going off the meter on the radio to measure IC current and a antenna tuner meter to measure forward power/SWR. I think the meters pretty accurate, but can't be 100% sure.

I tried for a couple hours Saturday to make a contact with it, nobody came back to me. I had the mic gain way up, so maybe I was really garbled, over-driven and unintellagable.

I guess what I need to find out is, should I be able to get ~100 watts out with the IC current down at the 100 mA level? I would think I should be able to speak normally into the mic and get the needles to kick up, right?

 

[flat5]

Do you have access to an oscilloscope?
An RF volt meter?
An audio generator?

 

[Andy1845c]

I have a scope, but not an RF volt meter or a function generator.

 

[JimB]

Andy

Thinking about this a bit more,
you say that you can get a plate current of 250mA which should correspond to a DC input power to the PA of 150 watts (600v x 250mA),
for this you get 50 watts RF output, I would expect more like 75 watts (50% efficiency for a class AB stage).

Are you sure that you are adjusting the Plate and Load controls correctly? I suspect not.

Here is a procedure I would use on my FT200 if it worked!

Assuming that the bias is set correctly (60mA), proceed as follows:

Connect a dummy load to the antenna socket (do you still have that Cantenna?).
Select 14Mhz band.
Select Tune on the Function switch.
Set Mic Gain to minimum.
Set Plate to the middle of the 14 area.
Set Load tab to the left (clockwise).
Set the meter switch to IC.
Move the Rec-Cal-Oper switch to Oper and turn the Mic Gain to increase the plate current (IC) to 100mA.
Adjust the Grid control to peak the plate current.
Move the Rec-Cal-Oper switch to Rec to let the PA valves cool for 5 seconds.
Move the Rec-Cal-Oper switch to Oper and turn the Mic Gain to set the plate current (IC) to 150mA.
Adjust the Plate control for a dip in plate current.
Move the Rec-Cal-Oper switch to Rec to let the PA valves cool for 5 seconds.
Move the Rec-Cal-Oper switch to Oper and turn the Mic Gain to set the plate current (IC) to 300mA.
Adjust the Plate control for a dip in plate current.
Move Load tab to the right (anti clockwise), the plate current should increase.
Adjust the Plate control for a dip in plate current
Move the Rec-Cal-Oper switch to Rec to let the PA valves cool for 5 seconds.
Set the meter switch to PO (or if you have an external SWR/Power meter, look at this and leave the switch at IC).
Move the Rec-Cal-Oper switch to Oper.
Adjust the Plate and Load controls for maximum indication on the power meter, increase the Mic Gain until the plate current is 350 - 400mA and readjust the Plate and Load controls for maximum indication on the power meter.
Dont take too long doing this, 10 - 15 seconds or the PA valves will self destruct.
Move the Rec-Cal-Oper switch to Rec to let the PA valves cool.

If the radio is reasonable tune with reasonable valves you should now be seeing about 100watts output.
When you switch back to SSB, talk into the mic and set the gain control so that the meter kicks to around 250-300mA on speech peaks. Check the ALC, the meter needle should just flick now and again on speech peaks, if is moves back out of the green on the meter, reduce the mic gain.
On SSB dont expect to see 100w on the power meter, probably only 30 - 40 watts.

With that, I hope that I have not been teaching granny to suck eggs!

JimB

 

[Dean Huster]

Back on the original issue of cleaning, I worked for Tektronix at their Dallas and Oklahoma City Service Centers. They indeed did wash them with water and detergent as "awright" disclosed. There was very little preperation involved other than removing all exterior covers, high voltage covers, attenuator shields, plug-ins (from mainframes) and air filters.

They used low-pressure air (maybe 30 psi) so they didn't rip out some delicate plug-in attenuators with the unregulated 150 psi and used a siphon tube to draw the detergent water into the air stream. The detergent used was Kelite, a powder that's dissolved in water and designed specifically for the cleaning of electronic equipment.

After the washing, the equipment is thoroughly rinsed with clean water and low-pressure air is used to blow the majority of the remaining water out. IPA is then squirted into all the attenuators and other switches to displace water. The unit is then put into a large low-temperature oven for three or four days to dry out and then all the covers and air filters are reassembled onto the scope.

Now you have to remember that a Tektronix scope that was made in the 1960s through the 1980s was a robust, high-end item of industrial equipment built with only the finest of components. You have to consider that consumer-grade radios of the era we're discussing had a lot more delicate and less-expensive components in them, many which may take on water and remain moist for a long time or some that are made of materials that might dissolve with water. I wouldn't hesitate to wash an item of industrial electronic equipment; consumer-grade equipment would give me pause.

Drying can be done in a home oven providing you set the thermostat until the oven just kicks on, monitoring the temperature to insure that it doesn't get too hot. Remember that unlike the industrial equipment, consumer-grade stuff of the 1950s and 1960s has a lot of wax associated with capacitors, inductors and RF/IF or HV transformers that will easily melt at even modest oven temperatures. Also, the kitchen oven is used to bake cookies and as such, has poor air circulation except for the lone vent tube up through the back burner. The big drying ovens have internal fans to move air around and out to get rid of the moisture. An alternate method is to set the equipment out in the hot sun on a dry summer day, maybe for several days. Even drying in the attic may be good, providing that the attic doesn't get overly hot.

I too would recommend that compressed air be used to blow the dirt away. I don't much like the idea of a vacuum cleaner as it's more of a "contact-oriented" system where a wand could damage an old, frail component where the air is more of a "hands-off" method. I don't even know that I'd consider the IPA.

By the way, IPA can be had in gallons a lot cheaper at home supply places, lumber yards and paint stores as alcohol intended for shellac thinner.

Dean

 

[audioguru]

It has vacuum tubes so it must be very old.
Where will you find replacement vacuum tubes when they wear out? Did a Soviet jet fighter plane crash near you?
Does it sound as bad as its age?

Have you heard how wonderful a new radio sounds?

 

[Andy1845c]

Jim - Thank you! I really appreciate you taking the time to give me some input. I don't have time tonight to hook it all up and try it, but I will make the radio my priority tomarrow after work. I will post back and let you know how it goes. I do still have the Cantenna. Man, you have an awsome memory.... But also have a dummy load that measures the proper resistance. The Cantenna has gone a bit high.

Dean - Thanks for your input on the cleaning topic This has been an interesting topic.

AudioGuru - Yes, its old, its got tubes, i'm sure it doesn't sound as good as a new radio, but what the hey, i'm young and dumb and having fun with it. Its got alot of enjoyment left in it.

Everytime I pass a MiG crash site I check for good tubes. Sadly they are always broken.

 

[JimB]

Dean,
Good description of the Tektronix cleaning process, but obviously needs to be organised on an industrial scale.

I too would recommend that compressed air be used to blow the dirt away. I don't much like the idea of a vacuum cleaner as it's more of a "contact-oriented" system where a wand could damage an old, frail component where the air is more of a "hands-off" method.

I disagree with you on this point.
1 Having blown away the dust with compressed air, where is is going to go? All over the place!
2 When using the vacuum cleaner, I am not advocating giving everything a good rub with the wand like I was trying to get something out of the carpet.
What I have in mind is gently brushing the dusty stuff with a soft 1" paint brush while holding the vacuum nozzle an inch or so away to suck out the airborne dust.

It has vacuum tubes so it must be very old.
Where will you find replacement vacuum tubes when they wear out? Did a Soviet jet fighter plane crash near you?
Does it sound as bad as its age?
Have you heard how wonderful a new radio sounds?

Well wouldn't you know it, I was wondering when these comments would arrive.
Yes AG, it is probably at least 25 years old, made around the time you were developing a grumpy old man complex.
Some of the old vacuum tubes are a bit rare and expensive now, but they are still available.
Yes it does sound as bad as its age and the equivalent new radio is no better.
It is SSB, remember? Like quacking ducks, all horrible, distorted and with the frequency response of a deaf person.

JimB

 

[duffy]

Everytime I pass a MiG crash site I check for one of those bitchin' slide rules that look like a pocket watch.
**broken link removed**

Has anyone ever tried just putting a dirty chassis in a dishwasher?

 

[awright]

duffy, I think a dishwasher is way too violent for cleaning an electronic instrument. If I was tempted, I'd try it out on a junk radio that I didn't care about to see what it did to the markings and cardboard components. And, of course turn off the post wash drying heat if you don't want to buy a new dishwasher. Be prepared to disassemble the machine in the event that the disintegrated cardboard and wax gets into the drain.

Dean said, "By the way, IPA can be had in gallons a lot cheaper at home supply places, lumber yards and paint stores as alcohol intended for shellac thinner." I think you'll find that the alcohol used for shellac thinning is ethyl alcohol with denaturants added to make it undrinkable. I believe that the denaturant formulas are actually exactly specified by the revenoors to be obnoxious and very difficult to remove by redistillation or any other amateur process.

I've never been impressed with the solvent capabilities of Isopropyl Alcohol.

awright

 

[duffy]

I've never been impressed with the solvent capabilities of Isopropyl Alcohol.

What, you never tried it as flux remover? Try is as flux remover. Use a Q-tip. Dissolves solder flux just as well as Tech-Spray flux remover.

 

[killivolt]

Everytime I pass a MiG crash site I check for one of those bitchin' slide rules that look like a pocket watch.
**broken link removed**

Has anyone ever tried just putting a dirty chassis in a dishwasher?

Actually I suggested it to the Company I worked for we used it in place of a board washer. They were way to cheap to buy a board washer they still had a 50 year old solder machine.

No, sanitizing wash's it might get to hot but, a normal wash may work for you. We used it with great success to my surprise.

I'm not so sure about anything with tubes maybe just modern day circuit boards yes it works.



kv

 

[Analog]

Don't fix what isn't broken.

 

[Andy1845c]

Just an update for JimB -

I tuned the radio like you outlined and I can get ~75 watts out on tune, meter shows about ~20 watts on SSB. Maybe this is normal. I have not been able to make any contacts yet. Possibly my loop antenna isn't going to work. Maybe its not radiating like it should. I am not sure.

 

[JimB]

I tuned the radio like you outlined and I can get ~75 watts out on tune

What was the plate current when you had this 75 watts?

meter shows about ~20 watts on SSB.

Was this during normal speech, or a "whistle into the mic"?
Again, what was the plate current meter saying?

JimB

 

[Dean Huster]

Jim, when I use compressed air, I don't do it in my living room! I take the item outdoors or into the garage to blow it off. You just have to be so danged careful using a vacuum's wand, crevice tool or brush; even a soft 1" paint brush is dicey sometimes. It's just too easy to crunch ancient, delicate coils and RF windings, mica insulators on trimmer caps and such.

Dean

 

[Andy1845c]

Jim - Shoot. I ment to check that lasnight and I forget. I know at the 75W the IC current was just into the red part of the meter.

The 20W was speaking pretty loud holding the mic close to my mouth. Not exactly how I would speak if I was talking to someone in the room, but not yelling either. Whistling into the mic will make the power a bit higher.
IC current if i remember right was out of the red zone, but over the 100mA mark. Maybe thats just normal.

I should also note that before I tried your tuning method, I played with the meter 'zero" and "sense" controls a little. Maybe I shouldn't have. I don't have the tools to adjust it like the manual says, but the meter wouldn't kick up much, even with strong signals before. I just adjusted it a bit so the strong signals read 3x5 or 5x9 or so.

This may (probably) has changed my IC readings during tuning.

The biggest thing is I can't seem to get out on the radio. I try to check in on nets, call CQ ect. and nobody comes back to me, yet I can hear my voice come through my cheap weather radio speaker, so i much be putting some kind of signal out.

Maybe I should scrap the loop antenna for the moment and try something simpler. Its so close to the ground (about 6 feet to the bottom) maybe its just not getting out.

My local radio club is meeting next month. I am planning to go join and hope that theres some friendly folks there that I can learn from.

Everyone - Just to update on the original dust problem - I took it outside and used compressed air to carfully blow as much dust out as I could. Some came out but not all. Then I used a brush and carfully brushed some of the stubborn spots and got a little more out. I also used some contact cleaner in the corner of a rag to carefully wipe off some of the goo on the metal surfaces. Overall it came out okay. Looks much better inside.