While ARRL reports about 250 registered JOTA stations in the USA, the very small country of the Netherlands has at least that many ;-). And we're looking for scouting stations elsewhere in the world.

A few useful data points:

The German amateur radio club DARC organizes a contest during the very same weekend as JOTA, causing severe, severe interference. There are contest-free segments, so listen for us there, see http://www.scout.org/en/information_events/events/jota/all_about_jota_and_how_to_join_in/how_to_avoid_contest_interference

There will be some two dozen stations reachable through our IRLP-capable repeaters. Call us on IRLP node 8600, 8610, 8620. We'll also monitor reflector 9091 which seems to be set up for this.

English is not a native language for our children, but is tought at school. Our kids may need a little encouragement so they learn that their English really does work for them. Please encourage them!

If you want to get an impression of our activity. have a look at http://jota-joti.nl. This is in Dutch but the site works remarably well though google translate. You'll find attendance lists and maps there. We're in the big blurry spot in the southeast on the map.

73,

Geert Jan PE1HZG

As to the transistor dummy load, keep in mind that the Hfe (the amplification factor) of a transistor raises when the temperature goes up. That is, assume a transistor with a Hfe of 30. Give a base current of 100 mA and it will draw 3A (transistors are *current* sources, not *voltage* source).

However, as the temperature goes up, Hfe raises to 35. Hence, more collector current and more dissipation, more dissipation is more heat, more heat is more Hfe... thermal runaway.

The easy way is to keep an eye on the meter and adjust the base current. The advanced way is to use a control circuit. Me, being a lazy bum I do keep an eye on the meter. YMMV.

73,
Geert Jan PE1HZG

The repeaters I maintain DO output a CTCSS tone. This has several advantages:

• * The radio does not open on other signals, e.g. when conditions improve
• * The squelch doesn't break when you walk past a noisy, radiating cash register e.g. in a shopping centre
• * My repeaters ID every 5 minutes (Netherlands, different rules). The radio does not open on ID alone, only when there is activity. After 35 years people tend to know the callsign of the repeater..

The bottom line: check, or ask the repeater owner. I publish the details on qsl.net/{pi3ehv,pi2ehv,pi6ehn}

73, Geert Jan

A recent review of these in the German magazine Funkamateur reveals that the spurious suppression on VHF is dramatically poor and way, way below minimal requirements. I'm no expert in FCC rules, but 25dB suppression will certainly not pass FCC requirements by a large margin.
I believe this high level of spuri will attract acctention of the enforcement folk.

Conclusion: while some Chinese radios are compliant (or would be compliant if they would be tested), some are not. The Baofeng UV3R is on the other end of the scale. If you mind keeping your license, please test with an analyser before you transmit.

Of course, your mileage may vary.

73, Geert Jan

The 857 uses EEPROM storage so "shorting" as suggested does not work.

I'd suggest to disconnect and re-connect the short RJ45 cable between detachable front and the main radio chassis, both ends. That has caused trouble in other cases.

Make sure all accessories (morse key, tuner, PC) are disconnected and re-power up.
Specifically, the radio does weird if the CW key is stuck when it is powered up.
This is a safety feature.

Also, make sure all buttons on the front operate correctly and freely and none are stuck.

Disconnect the microphone and re-try. You did connect the microphone in the left connector and the front in the right connector (I don't think it works the other way but the mic connector in remote mode is pretty advanced, so..)

73,

Geert Jan

An 897 (and, I suspect, the 450, since it may share some of the design), draws a sizable power surge if powered up. I have had lab power supplies go into current protection because of this.

Also, a poor connection in the power cord may cause the voltage to drop, causing the CPU to shut down, then restart, etc.

Test with a power supply with more reserve, or a car battary, and check the power cable wiring.

73,

Geert Jan PE1HZG

The FT90 has, like many Yaesu radios, a diode protecting against reverse polarisation at the power input. If  the radio is reversed, the diode will short out. This is a catastrophic failure: the diode burns, but the failure mode is a permanent short.

What not to do:

• * Remove the diode
• * Remove the fuse, short it, etc

A reversed radio where the diode has failed can be fixed for less than a dollar, the damage done without diode would render the radio useless even for parts. Believe me, I've seen it multiple times.

I think (but cannot verify right now) that the diode also protects against overvoltages.

What to do? First, make damn sure polarity is OK, then test if the diode has failed (this is a lot easier if you temp remove the PCB - not difficult). If it's the diode, find out what happened.
If not, you'll have to find where the short is. But the protection diode is a good first guess with more than 75% chance.

Whatever you do, only tinker if you have a power supply with current limiter that can be set *very* low so that a short, etc doesn't cause burns.

73,

Geert Jan

There are 2 factors here:

Jumpers (not soft mod, jumpers) will define the internal tables: TX/RX range, band plan for ARS etc.
You'll need to change the jumpers and reset the CPU to change these settings

The radio was aligned for the USA bands (and hence, for different centres of the bands) as the radio sold for EU market.
I don't expect the changes to be big, but the differences are mentioned in the alignment procedure.

The radio will always show it's the USA model: it will have FCC approval on the sticker, and may not have CE logo on it. Why hide it's real origin?

Geert Jan

The service menu is intended to adjust-out natural variations in the components used. Hence, there is no "factory settings", other than aligning the radio, with the appropiate equipment, according to the specs.

"Values for other radios" do not apply to your radio because the component spread is different.

Find someone with the appropiate test equipment and adjust your radio that way. copy-ing values makes no sense whatsoever.

Geert Jan PE1HZG

Hamradio is technical, not political, so this is an attempt to give a tech response.

There is a whole bandswitch circuitry, with diodes, on the PA board, I've bought some FT8x9 fixer-uppers and invariably one of those diodes has failed (though not always the same one).

I would do a few things:
1. Disconnect the green coax between the main (top) board and the PA (bottom) board, and connect your antenna directly to the green socket on the main board. Then, check if the receiver behaves the same way. I suspect everything will be OK in this case, which means that the main board is OK. Two hints: A. the funny connector used is sometimes found in older high-end VGA monitors, and B. the receiver is now completely unprotected so be very, very careful with static on the antenna, large signals and other mishaps.
2. The main (PA) board is reasonably easy to diagnose  with a DC meter and some thinking. You can measure the PA board on top and bottom side by disconnecting both red and green coax and the antenna connectors soldered to the PA board: all you need is the cable to the power supply, and the white flexfoil to the main board. Frequently, a diode has shorted, completely confusing the whole receiver bandswitch circuitry.

NOTE: there have been a few changes in this part of the PA board over the various lot numbers, and in some cases, circuits were updated by patching the PCB. You probably will need a current (rev C) version of the service manual, instead of the obsolete rev A that is floating on the Internet. Yeasu sells these for ~EUR 10,- so that should not be problematic.

By far the easiest way to verify correct operation is with a test oscillator with calibrated output levels, my stabilock paid dividends but I realize not everyone has this.

Yaesu is easy to talk to for parts but keep in mind they really want Yaesu part numbers.

Hope this helps,

Geert Jan PE1HZG

On my 897/857, the middle pin is actually fixed and does not turn around. That would suggest your plug is broken, and may need replacement; adding a stiffer wire might break the PCB.

Note that the European version has one PL, one N connector; I believe the USA version has 2 PL plugs, perhaps they are different.

Geert Jan

That should be 14.2 volts, not 13.8 volts, on the MIC plug, sorry. Basically, it's the input voltage, with a 47K resistor (R1157) in series.

Hi Darryle,

Thanks for your response. Let's see if I can help (that is, if you want to fix this yourself)

1. Flexfoil: the main board on top, including the PA driver stages, are fed through this flex foil. You can (carefully!) pull it up straight, then re-seat it. Probably best if you grab it on the blue tab, not on the foil itself. Chances are that after all these years, the connection has gone a little soft (haven't had that on my 8x7's yet, but I had this on other equipment w/ this foil)

2. Serial: 6M68, 2006, but more important, lot 68. Yaesu made a number of changes in the power-on circuitry over the years, but I believe yours is good to go.

You might want to check to make sure you still have good power on the radio once it switches off: I am a bit suspecious of the power supply/cabling, still.

Specifically, measure the voltage on pin 8 of the MIC plug (to GND). You should measure 14.2 volts, and it should go to ground if you briefly press the power button. 13.8V should still be there once the unit switched itself off.

A little background info (check the schematics that came with the radio): the circuit of interest is around Q1031 (left of the main CPU, Q1049). When you press the power button (either on front or on the microphone), you ground the common cathode of D1033.
This grounds the gate of Q1031, and causes 13.8V ("13.8VUS") to go via Q1031, to Q1028 (5V voltage regulator) and Q1030 (power-on reset circuitry, only gives a short pulse). If all is well, the CPU Q1049 will switch Q1035 which keeps the gate grounded and hence the radio on. Note that the CPU also knows the power button is pressed, via the other diode of D1033.
If you switch the radio off, all that needs to happen is for the CPU to stop driving Q1035.

Measuring this is not trivial, because most of these components are on the *bottom* of the main (top) PCB. But, you're working on the DC circuitry of the board, so you don't need the green coax (receiver input), or the red coax (transmitter output). You can safely operate the radio with these disconnected. (if you feel uncomfortable with leaving the driver stage unloaded, pull jumper J1004 and flip switch S1001).

What I have done, is:
1. Remove the top PCB, disconnecting everything (flexfoil, coaxes, cable to front, cable to mic plug.
2. You are going to flip the board around the side that has the flexfoil and you don't want to short the PCB, so put some tape over the right ledge of the enclosure as the PCB will rest on it
3. Re-connect flexfoil and flip the board upside-down; connect front module. I found it easier to connect an external speaker on the 3.5mm jack instead of re-connecting the internal speaker.
4. Now you can measure. Believe me, you're going to learn about the Adobe reader zooming functions.
5. Note that Q1014 (7808 stabilizer) gets hot. This is normal, since it's not colled now. The other device that needs cooling (Q1105) is just the LF PA, and it doesn't get warm at all if you keep the volume down.

Hope this helps, and let us know how it goes,

Geert Jan PE1HZG

The modification itself is easy enough: open top, remove module on the far right, replace with TCXO module, close lid.

The question is why you'd want the TCXO. It is for higher frequency stability, especially with changing environment temperatures. That assumes A. you're operating in changing temperatures (mobile, portable, outdoors) and B. you use modes that need this stability, think of PSK31 or similar: FM and SSB don't need it.

I have several 5x7 radios, both with and without TCXO's and I have not found a strong need to equip all my radios with TCXO's. My 817 (non-ND) has TCXO, but I bought it so I'd have stability (for testing purposes) outside, never found a need for that.

So, to answer a question with a question: why do you think you need the TCXO module?

Oh, and if you're not sure you already have it: the regular xtal oscillator looks like a small PCB with SMD components on it, the TCXO looks like a PCB with a small metal box on it, with a hole for adjustment.

73,

Geert Jan

There is a white flexfoil cable between the PA board (on the bottom) and the main board (on top). You might want to take it out and re-seat it.

What does the voltage on the display say during the 10 seconds it runs?

Have you (or someone else) fiddled with the service settings (wrongly named "hidden menu" - if you don't know what I mean, so much the better).

What lot number do you have? The serial number looks like 9N99888888. I'm interested in the first 4 digits/letters.

During the 10 seconds it works, can you make a full-power FM transmission, so full 50W on 2M?

During those 10 seconds, can you switch it off and on again?

If you or your friends have a DTMF mic, try the power button on the DTMF mic. Note that most of the other settings don't work w/o changing menus - just check the power button on the mic, that's all.

Is this with a bare unit, that is, nothing connected to ACC plug? Are you using an ATAS antenna? Does this also happen if both antennas are disconnected?

If you press the power button only briefly, the radio will switch from slow tuning to fast tuning and vice versa. With fast tuning mode, a "running puppet" shows on the display. Can you confirm that in these 10 seconds, you can switch on/off the fast tuning mode?

73,

Geert Jan PE1HZG