Anti-Kenwood rant

[N8YX]

Not so much against the performance of the gear itself, but of some questionable construction practices.

To wit:

Spent the majority of last evening troubleshooting a problem with an R-820 which somehow "migrated" to another one. Out of a total of three that I own, two are currently on the bench getting refurbed. One was working, and the other's modules (PLL, counter, oscillators, etc) were tested one by one in the 'good' chassis to make sure they operated correctly. All except the IF-A module, which contains the various crystal filters. When I put the "suspect" radio's original IF-A board in the known good rig, said rig no longer works....and I get a nice pronounced hum through the speaker.

Tearing into things further, I find that any substantial load placed on the 14v line now causes this symptom. It was intermittent but now it's permanent.

Hmm... :chin:

Tracing back through the schematics, I find the 14v rectifier assembly (which supplies power for the entire rig) is composed of 4 discrete diodes and is mounted on the friggin' band converter board! :shock:

When I extracted said board, I find that I2R losses have enabled a couple of the diodes to partially unsolder themselves, thus reducing a full-wave bridge to a fraction of its former self.

But Wait! There's More(ons)!

Kenwood's designers also thought it would be "efficient" to use part of the board to mount a couple of solder posts that connect 115-230VAC to the rest of the rig, and one serves as a tie point for the hot end of a line-noise suppression capacitor. It's located very near the diodes, and when they heated the board up they caused the terminal to become partially unsoldered...which accelerated its own I2R thingy...

Rant:

Why in hell can't some firms eat the 35 or so cents a terminal strip costs and do a discrete bridge rectifier assembly correctly by means of mounting it directly to the chassis? Failing that, why in hell can't some firms eat the dollar or so cost for the part and use a monobloc bridge rectifier and heat-sink the damned thing to the rig's chassis?

<- This is my "Pi$$ed-off" face

/rant

As Kenwood produced it, the board's design is also somewhat of a fire hazard. I'm giving serious consideration to a redesign of the whole area... :wall

In retrospective, I suppose I was lucky that the bad board created a condition which drew my attention to a potentially serious flaw...

[kd6nig]

If I had to bet money, I bet you'll find similar circuitry in all of their items that require said voltages.

Its probably something they use across the board, and they figure "it works in a car stereo, it will work in a ham radio!"

[N8YX]

If I had to bet money, I bet you'll find similar circuitry in all of their items that require said voltages.

Its probably something they use across the board, and they figure "it works in a car stereo, it will work in a ham radio!"

I wouldn't doubt it. Over the years, I've seen a number of "questionable" design concepts re-used throughout a given manufacturer's product lines.

An old (now retired) boss of mine could tell you some interesting stories about one of his former employers and their cost-cutting "measures" ... :whistle

[N8YX]

Found and fixed another problem. This is applicable to both the R-820 and its cousin the TS-820S:

On the underside of the receiver is a board with a handful of components, including two 2000uF, 25WVDC capacitors. One filters the main 14vdc line; the other, a 9vdc line. These are rather largish caps and are held to the board by virtue of solder alone. Wiggling one will crack the foil traces which connect it to the balance of the circuit. Vibrating the capacitor over the course of many years will also cause the foils to crack. I'm not surprised this happened, given the number of times that radio has followed me from 'Point A' to 'Point B'.

Yaesu did this better: A bit of glue was used on the base of each large cap to impart mechanical stability.

Receiver #2 is well on its way to being restored as well. After cleaning up a sloppy repair job on the 'filter' board, I poked around the AF-AVR board with a voltmeter and found that the 9V regulator's pass transistor only had 2 of its 3 legs soldered to the foils. That extra leg is there for a reason ...

[N8YX]

Update - a little Peter Gabriel is in order:

"The more I look...the more I find;"

Had a dim readout tube which would brighten randomly, and one of the digits would alternately flash its segments. Doing a little poking around, I found

- Cold solder joints on the display connection headers;
- Cold solder joints on the AF-AVR board;
- Cold solder joints on the counter mixer board;
- A bad .33uF tantalum cap on the counter mixer board;
- A broken terminal inside the display connector

Fixing the above took me most of this evening. Yesterday, some crystals I had ordered via eBay showed up and I swapped out three of the stock band crystals - two in the PLL unit and one on the converter board - for the new arrivals.

The set covers 6.5-7.0, 7.5-8.0 and 26.5-27.0 in the new ranges.

Also got rocks for 12M and 30M in the mail, but those are going in another TS-820S/R-820 pair.

Most of the electrical issues have been sorted. Just need a few parts along with a shield for the filter unit (which I'll build) and the receiver is ready to be reassembled then placed in line with its siblings.

[KB3LAZ]

Update - a little Peter Gabriel is in order:

"The more I look...the more I find;"

Had a dim readout tube which would brighten randomly, and one of the digits would alternately flash its segments. Doing a little poking around, I found

- Cold solder joints on the display connection headers;
- Cold solder joints on the AF-AVR board;
- Cold solder joints on the counter mixer board;
- A bad .33uF tantalum cap on the counter mixer board;
- A broken terminal inside the display connector

Fixing the above took me most of this evening. Yesterday, some crystals I had ordered via eBay showed up and I swapped out three of the stock band crystals - two in the PLL unit and one on the converter board - for the new arrivals.

The set covers 6.5-7.0, 7.5-8.0 and 26.5-27.0 in the new ranges.

Also got rocks for 12M and 30M in the mail, but those are going in another TS-820S/R-820 pair.

Most of the electrical issues have been sorted. Just need a few parts along with a shield for the filter unit (which I'll build) and the receiver is ready to be reassembled then placed in line with its siblings.

Sledgehammer or shock the monkey?

[W6WBJ]

'YX, this receiver is now OVER 30 YEARS OLD, yet you are surprised that it needs a few repairs?

Do you have any cars that are over 30 years old? Did they ever need any repairs? Did you rant about them, too?

I think this is a good example of why so many people hate to do business with hams.

[N8YX]

'YX, this receiver is now OVER 30 YEARS OLD, yet you are surprised that it needs a few repairs?

Quite frankly, yes, and not so much due to design deficiencies as to poor fabrication techniques - at least in the two units I have on the bench. I own a number of Kenwood hybrids and none of the others show signs of cold solder joints and other 'issues' which I'm finding with these two.

Do you have any cars that are over 30 years old? Did they ever need any repairs? Did you rant about them, too?

Your argument is somewhat disingenuous, because (as we both know) cars were NOT designed by their manufacturers to have a long life span. Now on the other hand...I have a friend who owns a 1915 Harley J. It has been on the road for the last 25 years, with nothing more than fluid, plug and drive-belt changes...tires, cables and whatnot. And it's ridden quite a bit for a machine of its age.

I mentioned "sundry items" when referring to the Harley. In a radio sense, changing or replenishing that stuff would be considered the equivalent of re-lamping, re-tubing and aligning a rig...and not having to correct a piece of equipment which was the output of an evidently flawed manufacturing process .

I think this is a good example of why so many people hate to do business with hams.

The crew at Elecraft would tend to disagree with you, but there's a reason why their company will eventually unseat all of the major "players" in that space.

Further: If a company cannot produce equipment which incorporates proper engineering, materials choice and/or fabrication techniques in an effort to achieve an MTBF that is as long as practically possible then they deserve to go out of business. Gear isn't being marketed now as "disposable", and it certainly wasn't marketed as such in the period we're discussing.

Drake and Cubic both were caught in a conundrum: Rather than reduce the quality of their amateur gear offerings to meet the price point of their Japanese competition, they pulled out of that market altogether and focused on the commercial and military markets. If you've ever been inside a TR7 or an Astro 103 you'll understand how "quality" amateur gear should be executed. Ditto the Signal/One line and a couple others.

Both of these companies used double-sided, glass-epoxy, silver-plated through-hole board technology while Kenwood used phenolic, bare copper, conformal-coated boards in their equipment. Kenwood's choice of connector headers (moreover, the tin plating used on them) along with the choice of solder and board fabrication technique almost guaranteed a rash of cold solder joints.

But only in some production runs. Perhaps someone wised up? Or maybe some cost-cutter got what he or she thought was a deal on raw materials and ended up staging a future failure by means of improperly wetted joints.

This phenomenon tends to repeat itself throughout Kenwood's model lines, so IMHO it's not a chance occurrence. Evidently, someone isn't thinking all of the angles through...

Meanwhile...my Drakes, Cubic and FT-901 lineups continues percolating along with minimal maintenance. Yes, the Molex KK156-series connectors need an occasional shot of DeOxIt but one of these days I'll probably replace them all with gold-plated versions. And that, folks, is the ONLY recurring problem with Bob Senior's products.

Did I mention I that I own later-model Kenwood stuff as well? And that I have to keep fixing the display headers on the VHF/UHF rigs? And that I had to recondition and rebuild the VCO circuits in my TS440S/R5000s due to (you guessed it) yet another implementation screwup.?

To Kenwood's credit, they have gotten a bit better as of late. Some of the other manufacturers are beginning to pull some pretty bone-headed moves when it comes to design. Witness the PA driver transistor arrangement in select late-model Icoms ... :roll:

[PA5COR]

10 year daily use of the FT 847
On/Off switch busted, new one will be put in next weekend.




That's all

The modifications are no repairs.

[N8YX]

10 year daily use of the FT 847
On/Off switch busted, new one will be put in next weekend.




That's all

The modifications are no repairs.

That's the thing about most (but not all) Yaesu equipment: It just tends to work.

I can think of a few exceptions, the FT736 and its questionable internal power supply being one of them. If you run the rig from an external supply, even that isn't an issue.