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AUDIO PROBLEM ON A HENRY TEMPO ONE
5 APRIL 25 : I was cleaning up the Tempo One and Checking all the tubes, after I put it all back together, the audio sounds horrible, any idea what to start on now?
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Response, AD0PE, Gary,
My first thought is that you somehow cracked a bad or poor solder joint in the cleaning process. If you have a good “O” scope, check the input signal to the IF after the filter. It should be smooth and not shifting when you are set to receive a stable input from a generator.
The block diagram came through unreadable. In the situation you have, I would do the “Half Split” method. Inject the IF frequency at the output of the IF section, with the final IF amp tube removed, to the plate terminal at the socket. Couple through a suitable cap, maybe a ,001 ufd and a couple hundred volt rating. Have the receiver set for CW. Slowly increase the signal level until you can either hear a clear tone or about 1 volt rms.
I don’t know what you have for a signal generator, so you may have to search a little with the generator tuning to get it dead on the IF. If you get a clear tone, set the modulation to 1Khz , and you should hear the beat tone if the product detector is working.
If not successful there, switch to pure audio and inject it into the first AF amp tube grid through a suitable cap, If that proves not to work, I would expect a soft tube in the audio section. If it does work then the product detector is likely bad. The 6AV6 was used as a product detector in some sets. Don’t neglect the function switch as it rewires the product detector for AM use. Not sure if the Tempo 1 had AM and may also as the LSB /USB function is changed..
If all the above leaves you clueless, then go to the first mixer section. Set your scope to read the mix LO and see if it is stable. If it is stable and of the correct frequency, set the generator to the antenna input at 50 microvolts and see what the mixer output looks like on the scope. If good, work your way through the IF section input and outputs of each tube.
AD0PE - Gary
THE COMMON DIPOLE ANTENNA
JUNE 2025 : Gary - AD0PE
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This is about an antenna type: the common wire dipole. Things I have learned by building and using them over many years both as an Amateur and in the military. Two areas are presented. First is the decision of options for erection. There are three common ways to rig a wire dipole. One support yields a sloping "V" configuration. Two supports yield a shallow open "V" and three supports which yield a flat or very nearly flat wire. All are normally cut to be 1/2 wavelength total. Several problems occur when any are to be used in the field. For the single support, obviously is finding a suitable support or bringing one with you. Same holds true for supporting the other versions. If you take the support(s) with you the questions are how do you raise the antenna and stabilize it. Trials have shown that the worst version is with two supports and the feeder hanging from the center feed point. That creates the shallow"V" which has poor radiation coverage. Putting up a three point suspended version solves some of the radiation loss but brings the complexity of siting and erection. Erecting the three required supports means you have to stabilize three separate structures. Three fixed supports already there means three trees in the line you want and high enough plus open enough to shoot lines through making that a real challenge. For the single support inverted sloping "V", remember that the ends of the wires are at high voltage potential in use and should not be anchored so the ends of the wires are close to the ground. Tether lines of rope are used to get a safe walk under height. Ropes go to stakes, rocks or some other tie down point. Lines do not need to be bow string tight. Flag the ropes in an area with other people about. For field use, I have found the single support dipole to be the best option in terms of erection and operation. An inverted sloping "V" dipole (also can have more than one set of wires, making a FAN dipole) gives more freedom for erection and setting in the preferred direction. The single support version is also more omni directional. Plus, it is often easy to move the wires around the center pole or tree to change the desired strongest direction as long as the real estate is available. Just pull the stakes and move the wires, re-stake. Keeping them in a nearly straight line , 90 degrees to the desired direction is preferred. By doing a little paper drawing, it is easily seen why the sloping "V" works. Draw a straight line, to represent a flat plane dipole. One with three supports pulled very tight for minimal sag in the wires. Mark the center as the feed point. Now superimpose the transmit current waveform on one side from the center point. That is a quarter wave with the peak at the feed point. Next draw vertical lines from the line representing the wire to the current wave form line. Those vertical lines represent radiation intensity as the current wave moves along the wire. Imagine the classic doughnut radiation pattern that a dipole gives. The wire runs through the hole. Radiation is from the page to you and around the imaginary doughnut and away from you through the other side of the paper. Nothing of any strength will radiate from the end of the wire. Now repeat the drawing of just one side of the dipole a second time and cut it free from another piece of paper. Set the feed point to overlap with the first drawing. There should be the original on the bottom and the new one directly over it. Put a thumb tack or push pin through both center points. Tilt the cut piece with wire free end downward, say about 30 degrees. As the angle changes, so does the radiation angle of the transmitted wave as shown by the vertical lines drawn from the wire to the current wave form.. Keep the feed point overlapping with the pin. There is a point, near 45 degrees tilt, that the transmitted wave starts to cancel itself by coupling to the other wire from the center feed point. So most guides say do not tilt for an included angle of 90 degrees which is 45 degrees per side. At 20-30 degrees per side, both sides tilted the same, from my experience, you have the best compromise. Long distance as well as short can be covered and with an almost omni-direction pattern. The two support version is the best for NVIS work. The three support has the highest signal strength but over a much narrower angle. The complexity of the three support usually can not be realized in a field environment. Most of the factors also fit into a permanent location using a wire dipole Second area is the feed point, construction and attachment. Common practice used to be buying a device called a "Cobra Head" and using it. Military used them for many years. Simple and strong, but hard to find today. Options include commercial manufactured versions some with spark arrestors built in. For the home brew crowd, there are glass dog bones and a variety of products such as Lexan, plexiglass and glass fiber flats and rods. Go back to the drawing made earlier of one quarter wave length wire. From the feed point, maximum current, minimum voltage. At the free end of the wire, current is minimum and voltage is maximum. What they actually are in volts or amps doesn't matter. The quart wave can also be looked at as resistance. Minimum at the feed point and maximum at the free end. Somewhere close to the feed point is 50 ohms resistive. Trial and error can show you where to feed the antenna for a resistance to match the transmitter and feed line. Jx is going to be about lowest at this point also. How I accomplish that is quite simple. I attach the element wires to the center point insulator. Then attach the feed cable to the center of the insulator, so it is suspended safely. The insulator is hung from a very short loop of synthetic rope the is anchored to the pole. Using two small split bolts. I guess at a starting point and set the feed wire in place the split bolt at some distance from the center. Like 8 inches. Do both sides the same. Now take each end of the feeder, using enough to create a short delta match and fasten each end under the split bolts to the element wires at equal distance from the center point. Erect the antenna and take a reading by SWR or with an analyzer. Lower the center, move the split bolts and the ends of the feeder in if the resistance is too high or farther apart if it is too low. This works with coax and ladder line. At some distance, you will find minimum SWR and usually, minimum Jx offset. It will not likely ever equal zero Jx but will be relatively small. Make notes of those points and you won't have to do it again. Just assemble on the ground by notes and erect it. For what it is worth: I now use a collapsible flag pole for a center support. I found that the clamps will fail so do not rely on them. Now I have a screw type hose clamp on each section. I pull out the normal length and set the clamp against the lower section and tighten. One per section. A last one holds the suspension rope the has the center section attached. I use coax, either RG-8X or RG-8 foam as feeders. Duct tape at each pole section to keep the coax from flapping in the wind. Ladder line does not work well with my set up but a fiberglass pole fixes the problem of coupling from ladder line to the pole.
Gary Charniga AD0PE
June 2025
from: Sam - n0kei 15 may 2025
ATLAS 210X
I have an Atlas 210X that does not transmit or receive on 40 meters. All other bands work fine. The band switch was very dirty, I cleaned it however the issue still remains. When the switch is set to 40, I have low static on receive, does not change volume or intensity when antenna is connected. No hetrodyne, whistles, etc. zero output on transmit. Anyone have any thoughts? Sam, N0KEI
ANSWER 1: From Joe N4RXV,
Check the taps on the band sw... they may be worn/lose/bent.
Measure voltages on the common side of switches and see if
passing current, by comparing with working bands...
also check vfo for signal at both working and non working bands...
ANSWER 2: PROBLEM SOLVED
KEN - KO5Y 5 June 2025
I have been working on Sams Atlas 210 x ,with no receive or output on 40 meters only all other bands worked good ,I cleaned and checked all switches , and did voltage checks all seemed ok ,I found the problem the 40 meter osc, coil was not working I repaired the coil and problem solved, Ken
Heathkit SB102
I have a Heath SB102 I assembled in 1974. Has the original 6146 finals. I think the tubes may be getting gassy. When go to the TUNE position, the power output on an external meter is around 100w which is what it should be (I'm checking this on 40meters). However, it quickly drifts down to about 50w or so. Before I go and buy 2 new tubes, anything else I should check? Thanks. -- Dominick Golino
ANSWER 1: From Gary, AD0PE
You didn’t mention how fast the drift down of the output wattage was. I would check the drive voltage to the grids of the finals on key-down, if you have an RF volt meter or an “O” scope.. If not, check the cathode voltage and the plate voltage of the driver tube and see if it holds steady on key-down. If the driver is behaving correctly, then go to the screen voltage of the 6146’s and see if it holds steady on key-down. I am assuming the 6146 plate voltage is right and steady. While really great tubes, 6146’s don’t last for ever. Leaking bypass capacitors can give the indications you mentioned. But so can a few other areas cause it. The above should give you some information of which way to go from the driver input. Either towards the output or back to the pre-drive sections. Kind of a “half Split” method of trouble shooting.
ANSWER 2:
Swapping driver tube may be the quickest check for trouble... most of my rigs have 12by7 drivers to the 6146 tubes...
If you can swap that one first, "lots cheaper"
as mentioned check the voltages on the driver tubes and finals,
be extra careful with the final plate voltage ...
good luck...
Let us know what ya find...
joe b., N4RXV
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