KENWOOD TS850
Tras muchos años de operar con el TS430, compré de segunda mano el TS850 SAT. He notado una gran mejora en la sensibilidad de recepción, el manejo CAT abre un nuevo mundo con la conexión al PC. Es muy grato trabajar en los concursos (programa N1MM) y que automáticamente se entre la frecuencia en el log, o traspasar la búsqueda de dx-cluster directamente al equipo, no digamos ya la operación remota desde Internet. Los pocos menús que tiene son de configuración básica, no es necesario modificarlos, todo se puede hacer a través de los controles frontales lo cual lo hace muy agradable.
Adjunto un link donde se hay gran cantidad de modificaciones e instrucciones de reparación. "The repair page"
http://n6tr.jzap.com/850repair.html
Otras web interesante con fotos de reparaciones e información.
En la Arrl hay un documento de VE1FA, "TS850 13 años después" donde muestra su entera satisfacción del equipo incluso indica su predilección sobre otros mas modernos, también explica ciertos ajustes, "mods" y reparaciones.
Transcribo aquí su articulo, no copio el link por la posibilidad de que se pierda.
Continua en Inglés, English Follows !!!
The Kenwood TS-850SAT HF Transceiver — 13 Years Later
Dr Fred Archibald, VE1FA
Must modern HF transceivers be treated as “black box” appliances? VE1FA doesn’t think so, and his experience with the Kenwood TS-850SAT bears him out.
Hams have a long and proud tradition of technical innovation — tinkering. In the early years of Amateur Radio, homebrew transmitters and receivers were the rule. After World War II “scratch-built” transmitters and receivers became scarcer, but the rebuilding and extensive modification of military surplus and amateur gear was common. Your station and signal quality reflected your technical skill as much as your operating skill. As factory-built transmitter and receiver models aged, a rich collection of “fixes,” “mods” and various improvements for each accumulated in the amateur literature. Sometimes, these modifications even showed up in later models from the factory!
Since the advent of all-band, all-mode, synthesized HF transceivers most hams have become less interested in fixing and modifying and more involved with simply swapping the current radio for a new one that has more features. Recent amateur literature reflects this. There are lots of new equipment reviews, but there are relatively few articles on how a particular transceiver might be expected to perform over years of use or how to repair and improve it. Do modern HF transceivers have to be treated as “black box” appliances? I don’t think so.
Bonus Burns a Hole
December 1993: I’m happily walking home from work with an unexpected bonus check in my pocket. Hmmm. Fix the roof? Shoes for the kids? Bail for Uncle Marvin? A new radio?? Yes! A new radio!
I then indulged in that most pleasant of ham activities — looking at the current crop of HF transceivers and deciding which one to buy. What finally helped to make up my mind were the comments of James “Rus” Healy, NJ2L, in summing up the attributes of the Kenwood TS-850 his July 1991 QST “Product Review.”
“The TS-850 is a great value for its receiver alone . . . and for the price, nothing else even comes close to the TS-850’s performance,” he wrote.
No review of a new radio can tell you how you might like it after extended use, however, nor indicate failure-prone components and describe practical mods to improve it.
Since I first lifted my new ’850SAT out of that big brown box from Kenwood, my wife Helen, VA1YL, and I have made thousands of QSOs, including DXing, contesting, net operation, rag chewing and even SWLing. How has the ’850 lived up to that positive QST review of 1991? After 13 years of use, I agree with almost everything that NJ2L said about the TS-850. There were lots of things that Rus and the other reviewers overlooked, however.
Hidden Nuggets
The people who designed the ’850 clearly were not the same ones who wrote the owner’s manual. The Kenwood manual and the various reviews failed to mention some of the ’850’s abilities. Here are several.
· Push the 1 MHz button, and the radio will skip all unused memories as you scroll through.
· Pressing the SCAN and TX-M.CH buttons simultaneously when powering up the radio yields eight additional adjustments. The most useful is probably “01,” which lets you select different IF filters in transmit. If you’re a cheerful sort, set function 05 to “on,” and every time you turn on the ’850 it displays “HELLO” and sends it in Morse, accompanied by a Kenwood advertisement in CW (one could tire of that).
· Press the VOICE button while powering up the ’850, and many of its buttons announce their function in Morse code, including RIT, XIT, memories, VFOs etc. You can even enter a frequency via the front panel keypad and hear it in CW. What a nice feature for visually impaired operators!
· Unlike nearly all other HF transceivers, the ’850 has a separate dedicated receive bandpass filter for the 200 to 500 kHz region, making it a particularly good LF receiver.
Repairs and Maintenance
Out of the box all settings on my TS-850 were correct, and nothing failed over the course of five years, hundreds of operating hours and thousands of contacts. Since then, there have been four failures, most of which I was able to fix myself and learn from.
All TS-850S transceivers now are 10 to 18 years old. At this age, they need certain checks and adjustments made. Why not do these yourself? Many of the radio’s components and circuits are user serviceable. Here are five key checks and adjustments you can perform on your aging ’850. I’ve described them only briefly, assuming that TS-850 owners will have access to the factory maintenance manual — either an original or one of the inexpensive CD copies available on the Internet. Before proceeding, study the relevant section in the manual. You’ll need a digital voltmeter (DVM), basic tools, a good fine-tip soldering iron and an illuminated magnifier (or young eyes).
Frequency calibration: After at least 60 minutes of warm-up, tune the ’850 to the highest strong WWV signal, preferably 15 or 20 MHz, with the 10 Hz digit switched on. With the display reading 15.00000 MHz (for example) and the WWV tone clearly audible, switch between LSB and USB. If the tones are not identical, then remove the top cover and adjust TC5 on the PLL board — accessible through the oval hole on the left side — and correct the readout back to 15.00000. If the tones are now closer, you’re adjusting TC5 in the right direction. If not, adjust in the opposite direction. Continue this procedure until the LSB and USB tones on the WWV signal are identical at 15.00000 MHz.
Unless you have the temperature-compensated crystal oscillator (TCXO) option TCXO, it’s normal for the ’850 to drift 1 to 3 ppm (15 to 45 Hz at 15 MHz) between the time you first turn it on until it’s fully warmed up. Following your adjustment, the ’850 should be within 5 Hz of the true frequency at 10 MHz, once it’s reached operating temperature (ie, “warmed up”). Incidentally, many computer interface programs will display the ‘850’s frequency with a precision of 1.0 Hz.
Memory battery change/upgrade: On the digital board behind the faceplate is a coin-type lithium battery. If it measures less than 3.1 V, shows any sign of leakage or is more than seven years old, replace it. The battery is soldered to the board, but do yourself a big favor and install a battery holder (such as Mouser 122-2523-GR) when you replace it. Also, install a replaceable battery, such as the common CR-2430.
Remove the ’850’s case, raise the chassis on some ½-inch scraps of wood, unscrew the front panel from the frame and tilt the panel forward on its cables. The battery, exposed on the digital board, now can be removed by clipping its tabs in the middle, then carefully unsoldering the stubs with a good, fine-tip low-wattage soldering iron. There are many small components nearby that you don’t want to damage! The iron and all tools used should be grounded to the board with clip leads or thin wires, as the battery is in a static-sensitive circuit (see below). An illuminated magnifier will help a lot.
Now, solder in the battery holder. Depending on its style, you may need short pieces of wire to adapt it to the digital board. Be sure to observe and verify battery polarity! Now you’ll be able to swap out the memory battery in minutes, without delicate soldering.
Key phase-locked loop (PLL) adjustments: The ’850 service manual lists 52 measurements and adjustments for a complete alignment. Most never need to be touched unless there is a related component failure, but there are five settings for the voltage-controlled oscillators (VCOs) 1-4 and LO2 VCO on the PLL board that do drift over the years and are critical to good performance. I learned this when my ’850’s normally excellent receive audio became raspy. You’ll need just a jeweler’s screwdriver and a DVM with ±1% or better dc voltage measurement accuracy.
Following the service manual (pp 98 and 155), set five trimmers so the VCOs produce the specified dc voltages at the test points. Note: the LO2 VCO seems to be the most drifty and responsible for poor receive audio. To confuse matters, there are two test points marked TP2. Set the TP2 that’s outside the small shield box holding the LO2 VCO to 5.00 V. These adjustments are quick and easy, but be careful. The trimmers are small and delicate, and the adjustments quite sharp.
Figure 1 — The TS-850 CAR board, showing foil corrosion from leaky capacitors (now
replaced) and the removal/replacement of the 6631 DDS chips (see text). Note the
yellow ground wire going to the soldering iron (upper right). The dental pick,
used to lift the old chip pins during de-soldering, has a similar ground.
Check the carrier (CAR) board: The CAR board is just above the PLL board. Carefully examine the 10 surface-mount (SMD) 10 uF and one 25 uF electrolytic capacitors (the tiny aluminum cans) on the CAR board. Look for swelling, dark staining or corrosion of the surrounding board (Figure 1). By 2005, six of my CAR board’s electrolytic caps had begun visibly leaking, and eight of them measured less than 0.1 uF. Apparently, Kenwood and many other manufacturers bought batches of capacitors filled with incorrect electrolyte1, and this problem seems to be fairly common on ’850 CAR boards. Leaky caps must be replaced before they ruin the circuit board by shorting, opening or etching away the copper traces. Fortunately, only the SMD electrolytics seem to be affected, and they are only on the CAR board. In my limited experience, the bad series of caps is marked with blue ink, the good series with black ink. Replacements are available from Mouser2 and East Coast Parts.3
While you’re
looking at the CAR board, check the numbers on the four big surface-mount direct
digital synthesis (DDS) chips. If they’re 6631s, you have the older series,
installed in early ’850 production runs. These were prone to failure. If they
are 66312s, you have the improved chip. If you ever have a problem traced to a
6631 (as I did, with the radio displaying all dots lacking its CW sidetone),
then it is probably a good idea to replace all four with the 66312 chip ($28
each from East Coast Parts). I wonder if the 6631 failures are linked to the bad
electrolytics used to protect them from 5 V supply transients.
Can the average radio amateur actually replace a 64-pin static-sensitive SM chip
like the 6631 — or those tiny electrolytics, for that matter? When my ’850’s CW
sidetone failed I decided to try, even though at about age 60, my vision and
fine motor skills aren’t nearly what they once were. It was surprisingly easy,
but I found the following to be essential:
· a good illuminated magnifier on an articulated arm
· a Weller soldering iron with a thermostat and the new, very fine 700º F tip (#PT07)
· 0.4 mm flux-core solder
· a circuit board holder
· a dental pick (available at most hamfests)
Leave the CAR board on its metal plate for safer handling (Figure 1). A 24-inch wire to a screw on the soldering iron grounds it to the board, as does a jumper lead to the dental pick. Removal and installation of each chip took me about 20 minutes. Frequently clean and re-tin the soldering iron tip, use only tiny amounts of solder and watch for solder bridges. Don’t drink coffee beforehand. Too much caffeine can make your hands shake too much.
Your power supply: Hams may casually describe the ’850 as running on 12 volts dc, but in fact most ’850s run poorly at that voltage; certain parts, such as the dc-to-dc converter board, need more than 13 V to work properly. Connect your ’850 to a dummy load and to its power supply. With your DVM, measure the dc voltage entering the radio while in receive and at 100 W CW carrier output conditions. It should read 13.8 to 14.0 V on receive and no less than 13.4 V on transmit. If the voltage drop exceeds this, check at the power supply output terminals to determine whether the excessive voltage sag is in the cable or in the supply itself. Most supplies (including the Kenwood PS-52 designed for the ’850) have internal resting voltage and current limit adjustment potentiometers which you can set.
Many 20 A after-market dc supplies simply cannot adequately power the ’850, which requires 13.8 V at 20.5 A. If your supply cannot be adjusted to pass this sag/fluctuation test, you need either a heavier (or shorter) dc power cable or a better 13.8 V supply. I learned this the hard way and now use a well-regulated 35 A supply, which also powers various station accessories. A good supply will change less than 0.1 V when the ’850 goes from receive to 100 W out.
Improving the ’850
My TS-850SAT is a significantly better radio today than it was in 1993. If you’re preserving your ’850 for the Smithsonian, read no further. If, like me, you’re more interested in understanding, using and optimizing the radio, read on. All of the changes are simple, but it would be best to have some experience working on modern electronics. So, grab your pry bar, put a fresh blade on your hacksaw, light your propane torch and let’s improve the TS-850S!
Seriously, any idea for “improving” a finely engineered precision instrument like a TS-850S should be approached with caution. The amateur literature is filled with mods that either don’t work very well or that introduce new problems. I have done the following simple mods and am pleased with the result, but you should thoroughly consider and understand each before attempting it
Figure 2 — The separate receive antenna modification. A: foil trace cut here and
two 7 inch lengths of RG-174 soldered, one on each side of the cut. K1: 5 V dc
25 mA glass sealed SPDT reed relay (Z=50 ohms). VSA: surge suppressor identical
to one on relay board. D1: 1N4004 or similar. S1: mini SPST toggle on long #22
leads. No change was made to the ‘850 relay board other than cutting the foil
trace and attaching the RG-174.
Figure 3 — Rear of the modified TS-850S showing the BNC connectors for the
receive signal monitor and receive antenna and the receive antenna switch. Note
the factory AUDIO OUT jack. It is made of plastic and very fragile, and it’s
attached only to the IF board and not to the case. I soldered a wire from the
metal rim of the jack to a case screw to reinforce it.
Mod 1 — Separate Receive Antenna Input
The 1991 QST “Product Review” called the absence of a separate receiver input for receive-only antennas a “painful omission.” I agree, since I need one for my K9AY receive loops4. Figure 2 shows the third approach I’ve tried. It is by far the easiest and doesn’t have the dirty contact problems associated with the rear-apron toggle switch or unsealed relay mods. The key component, relay K1, must either have gold contacts or be completely sealed (preferably both), as the tiny currents passing through it on receive cannot burn exposed, non-gold relay contacts free of the dirt and oxidation which will accumulate over time and produce erratic reception. Many potted DIP and small glass-enclosed reed relays will work reliably.
Relay K1, D1, the voltage spike arrestor (VSA) and the two resistors are mounted on a 0.75 x 1.25-inch piece of perf board, next to the new receive antenna BNC connector (Figure 3). You also should install a second VSA to protect the 850’s receiver. These are available from East Coast Parts3.
S1 is mounted on a shelf edge, three inches above the face of the ’850 (Figure 3) and allows easy, instant shifts and comparisons between transmit and receive antennas.
Mod 2 — Better Selectivity
The ’850 receiver is wonderfully quiet, sensitive, free of birdies, and it exhibits great strong-signal performance. The stock SSB factory-default passband is too wide for crowded conditions, however, and the CW filter is an option. Using the slope tuning helps but emphasizes the relatively poor shape factor (skirt steepness) of the factory monolithic crystal filter at the second IF (8.83 MHz) and the ceramic SSB filter at the third (455 kHz) IF.
While Kenwood sells accessory filters, previous experience has shown that the large International Radio (Inrad) 8-pole discrete crystal filters are superior. I installed a 400 Hz Inrad filter at 455 kHz (Inrad 455H400A) and 2.1 and 0.25 kHz filters at 8.83 MHz (Inrad 88H2.1C and 88H250). These make the ’850 really selective. SSB can be left broad (2.7 kHz) for best voice quality in casual operating or narrowed to 2.1 kHz for difficult conditions. In CW or digital modes the 400 and 250 Hz filters can be used separately or cascaded for maximal selectivity. The ’850’s ability to switch filters independently of mode makes having a variety of filter options even nicer. These filters also make the slope tuning work better, as the new filters have steeper skirts.
The Inrad filters are larger than the Kenwood equivalents, however, so the 250 Hz filter must be fastened to the side of the RF shield on the RF board (double-sided tape) and connected to the filter socket pins by RG-174 coax, as explained in the filter instructions. After the new filters are installed, be sure to re-set the switches under the little door on top of the ’850, as explained in the manual.
Mod 3 — Improving the Noise Blanker
One annoyance was the ’850’s not-too-effective noise blanker. I have electric cattle fences nearby that are charged with 15 kV spikes, and the popping (and AGC de-sense) is very annoying on the low bands.
The ’850’s noise blanker is nearly identical to the more effective one in the earlier TS-940, except for two 0.01 uF bypass capacitors, C618 and C619. If you remove them, the TS-850 noise blanker takes out more pulse-type interference and eliminates it more thoroughly. The small noise blanker board X59-1100-00 (beneath the power switch) is carefully removed and compared to its diagram in the service manual. C618 and C619 are located below the two ICs, de-soldered with a fine tip iron and removed. A dental pick or tiny jeweler’s screwdriver is useful for dislodging them, as they are both glued and soldered in place. Now the blanker works much better on ignition noise, electric fence spikes and other pulse-type interference.
Mod 4 — Better 0.5-1.6 MHz Sensitivity
The TS-850 receiver has excellent dynamic range and immunity to overload. Nevertheless, Kenwood placed a 26 dB attenuator after the 0.5-1.6 MHz bandpass filter. This means the receiver has less AM band sensitivity than the average 1950s-era kitchen radio.
Invert the ’850, remove the bottom cover and the metal shield on the RF board. Find the labels identifying L8 and L9 in the left rear corner of the board, then find the two copper-clad holes (solder points) next to the label “.5-1.6”, very close to L9. Carefully remove the plugs and ribbon cables to the RF board and unscrew the board from its mounts. Form a small “U” jumper of fine bare wire to connect the two copper-clad holes. Lift the RF board and solder the ends of the wire to the hole pads on the underside of the board, thereby bypassing attenuator resistors R7 and R8. This requires fine solder and a very fine, clean, soldering iron tip. Carefully refasten and reconnect the RF board.
You now have an excellent radio for DXing on the AM broadcast band (BCLing)! I used it for many years in Montreal, where many AM signals are thousands of microvolts, and there was no hint of overloading or spurious signals.
Mod 5 — Received Signal Viewing
I’ve always liked having a spectrum scope to visually monitor both transmitted and received signals, so I acquired a flea market Kenwood SM-220 station monitor with the BP-8 panoramic adaptor. Unfortunately, while the SM-220 can display received signal waveforms, the ’850 does not have an appropriate output. The answer? Solder a 1/8 W 470 ohm resistor to the cathode of detector diode D32 on the IF board, attach the resistor’s floating end to the center conductor of a 7-inch piece of RG-174 coax and solder the shield to the ground pad next to D32. Install a single nut-mounted BNC connector on the lower right rear apron viewed from the rear (next to the receive antenna BNC — see Figure 3), connect the RG-174, and feed the ’850 detector signal into the vertical input BNC of the SM-220.
Now, by simply rotating the FUNCTION switch on the SM-220, I can monitor my transmit and receive signals or scan band activity!
Figure 4 — The modified TS-850S in its natural habitat, surrounded by homebrew
antenna tuner, DSP unit, linear, speaker, K9AY controller and SM-220 monitor.
The remote receive switch is mounted on a scrap of copper-clad board above the
‘850.
Mod 6 — Audio Improvements: DSP and a Good Speaker
The ’850’s quiet receiver emphasises atmospheric noise, especially on the low bands,Shortly after buying the ’850 I read the September 1992 QST article on DSP by Dave Hershberger, W9GR, and I bought his kit. The finished DSP (in an RFI-proofed box) simply plugs into the 2.5 mm audio output on the rear of the TS-850. I put multiple paralleled 2.5 mm and 1/4-inch phone jacks on the front of the DSP box to allow a variety of speaker and headphone connections. A DPDT mini-toggle switch allows the DSP to be instantly bypassed or inserted in the audio line.
If you haven’t tried audio DSP, you should! While it doesn’t render unreadable signals easy copy, it greatly decreases hiss, crackles and pops. Long periods on the radio on the low bands and on days with high A and K indices or distant lightning are much less tiring, and the auto notch makes the tuner-uppers far less annoying. It’s great!
There are also several assembled after-market DSPs available. I tried a Timewave DSP 59+ with the ’850, and it was very effective. By the way, don’t power the DSP unit from the ’850’s power supply. RFI from the DSP’s 20 MHz CPU may be conducted into the radio.
The ’850’s nicely finished steel case is, well, a nicely finished steel case, not a good speaker cabinet. Further, since most of us listen to a radio sitting in front, not lying on top of it, the small top firing internal speaker audio isn’t optimal. Despite many comments to the contrary, you do want high fidelity (ie, the ability to hear frequencies between 200 and 3000 Hz) in a communications receiver. Every bit of the original signal lost or distorted translates into reduced intelligibility. Additionally, light plastic and metal speaker enclosures nearly all resonate or buzz at certain frequencies, adding noise and distortion.
I put a good-quality 5-inch large magnet 8 ohm speaker in a 7-inch cube (with an open back) constructed of 5/8-inch plywood firmly glued and screwed together. All four speaker mounting holes are used to get firm contact between the speaker cone’s cardboard gasket and the cabinet, which then becomes an integral part of the speaker. Compared to speakers in light plastic and metal cabinets, the heavy wooden cabinet speaker sounds far better.
Summing Up
Learning enough about your transceiver to make real improvements in its performance — even simple ones — can be very satisfying. The radio changes from an appliance into an education.
Most of the TS-850S modifications described were first done by hams other than me, and much of their wisdom is online. A great first stop on the Internet is N6TR’s The TS-850S Repair Page. Links on that site will lead you to a wealth of troubleshooting and operating information on this fine radio. It is clear evidence that the classic ham spirit of technical innovation and idea sharing is alive and well. You are invited to join this tradition!
References
1Chiu, Y-T., and Moore, S.K., “Leaking capacitors muck up motherboards,”
Spectrum IEE 40 (2) pp 16-17. Feb 2003.
2Mouser
Electronics, 100 N Main St, Mansfield, TX 76063.
3East
Coast Parts, 2 Marlborough Rd, W Hempstead, NY 11552.
4Breed, G., “The K9AY terminated loop: a compact directional receiving antenna,”
QST, Sep 1997.