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Author Topic: Elecraft K1 issues  (Read 4177 times)
M0JHA
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Posts: 646




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« on: May 10, 2010, 06:14:20 AM »

i purchased a second hand K1 a few days ago..  after a few initial tests it seems all is not how it should be.. Firstly i noticed if i had the power set to 2 watts on the rig it wouldn't always put this out even into a dummy load.. sometimes it would put out say 3-4 watts but if i re entered the menu and re adjusted power to 3 give it a few taps with the key and then re adjusted to 2 watts it would then put out 2 watts

i also noticed yesterday if i set the power to 2 watts it will increase moving up the band and decrease moving down the band..

if i set the 40m vfo to say 7.030  and change band to 30m its also showing 0.30 give or take a few khz..  its the same if i move to 20m , display reads 0.30 ish .. i have gone over this setting different freq and all band sem to match each other ..

the vfo seems slightly off also ,listening to a signal on my 817 and the K1 irt seems the K1 is just slightly off  by maybe 500hz - 1 khz( i trust my 817)

does this just sound like it needs aligning.. the rig works and iv made qso's no problem it just doesn't seem aligned..

billy m0jha
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G3TXQ
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Posts: 1530




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« Reply #1 on: May 10, 2010, 07:56:38 AM »

Billy,

The power control on the K1 isn't great. If I set the menu for 2W the output can be as high as 3W. I wouldn't worry too much if you are getting reasonable power out.

The VFO is a simple free-runner, and the display is a crude frequency counter; so if the VFO is set 30kHz from the bottom band edge on one band, it will be roughly 30kHz up on all bands. I just tried mine and got:

7,037kHz, 10,131kHz, 14,030kHz, 21,027kHz

The differences are caused by the differences in the band heterodyne xtal oscillators.

You may be getting confused because the display normally only shows the final 3 digits. So, if I'm tuned to 10,131.5kHz the display will show "31.5". When I tap the "Band" button I would see "10" followed briefly by "131" and then it would revert to 31.5. I guess it's the only way to show you the complete frequency on a 3 digit display.

Read-out accuracy is dependent on the processor clock frequency; as far as I know you can't adjust it, so you could easily be a few hundred Hz out.

Edit: there is a procedure for calibrating the frequency readout separately for each band. Page 41 in my Manual Rev F.

73,
Steve G3TXQ

« Last Edit: May 10, 2010, 08:12:07 AM by Steve Hunt » Logged
M0JHA
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Posts: 646




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« Reply #2 on: May 10, 2010, 09:52:57 AM »

cheers for the reply steve, yes im getting power out no problems its not an actual power out issue as in a finals fault , i just like to work 2 watts out so it would be nice to get that without having to mess around when the rig is set for 2 watts..

sounds like your freq readings are what mine is doing .. i understand the freq display i was just a bit confused as i had 20m set at 14.060 then went to 40m 7.030 for a bit and when i returned to 20m i wondered what had happened..

one other thing you may be able to help me with .. when i tune using the internal atu it finds a match , reads vswr but then sticks and does nothing till i hit a button , does it matter which button i press after tune up has finished to return to rx and to save the setting ?..

billy
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G3TXQ
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Posts: 1530




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« Reply #3 on: May 10, 2010, 10:00:14 AM »

Billy,

I think this is the relevant section from the ATU manual:

Quote
Enter TUNE mode. Power will be reduced to about 1.5 watts and displayed briefly, then SWR will be
displayed while the ATU matches the transmitter to the load (usually 1-5 seconds). If the match is
already very good (< 1.2:1), the tuner’s L and C settings will not be changed.
• When you no longer hear any relays switching, tune-up has completed, and the final SWR is
displayed. At this point you can optionally tap W P M + or W P M - to change the selected power level.
Pressing any other switch or tapping the key will cancel TUNE and restore your specified power.
• ATU settings are stored in EEPROM, and will be recalled instantly whenever you change bands.

I'm not sure if you have the Manuals; if not they are free to download from the Elecraft site.

73,
Steve G3TXQ
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M0JHA
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Posts: 646




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« Reply #4 on: May 10, 2010, 11:01:06 AM »

yes got the manual but that passage confused me.. by pressing any button to cancel TUNE and restore specified power.. does this mean by  pressing any button the tune cycle is cancelled  BUT THE MATCH SETTING STORED

or does it mean the tune cycle has been cancelled fully and the setting will not be stored..

billy
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G3TXQ
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Posts: 1530




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« Reply #5 on: May 10, 2010, 01:04:57 PM »

yes got the manual but that passage confused me.. by pressing any button to cancel TUNE and restore specified power.. does this mean by  pressing any button the tune cycle is cancelled  BUT THE MATCH SETTING STORED
Correct, although it might be more accurate to say the TUNE cycle is 'complete' rather than 'cancelled'.

73,
Steve G3TXQ
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M0JHA
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Posts: 646




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« Reply #6 on: May 10, 2010, 01:11:57 PM »

cheers steve..
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M0JHA
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Posts: 646




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« Reply #7 on: May 11, 2010, 09:36:20 AM »

Billy,


The VFO is a simple free-runner, and the display is a crude frequency counter; so if the VFO is set 30kHz from the bottom band edge on one band, it will be roughly 30kHz up on all bands. I just tried mine and got:

7,037kHz, 10,131kHz, 14,030kHz, 21,027kHz




just one thing steve.. mine is doing the same thing ONLY on 30m its 100KHz out .. as yours is at 10.131 mine would sit .031...  i take it from flicking through the manual in the spare time iv managed to get that this was pre determined at build.. the manual has been checked off as the build was worked through . looking at the 4 band filter board instruction manual the 150KHz range has been ticked off ( page 6)  meaning xtal X3B would of been used and the lower band edge being 10.000MHz..

this doesnt sound right for a UK builder does it? it may be a case of the builder simply wanting to cover all the band but i would of thought the 80KHz would of been the correct one to use.

billy
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M0JHA
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Posts: 646




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« Reply #8 on: May 11, 2010, 10:23:16 AM »

sussed.. it looks like it was intentional.. not sure why though unless it was simply to have that bandwidth available..

billy
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G3TXQ
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Posts: 1530




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« Reply #9 on: May 11, 2010, 11:05:40 AM »

Billy,

I think you may still be mis-reading the display on 30m.

Press the band switch until you get to 30m, then release it. Assuming you have the VFO set about 30kHz from the end of its range you should see:

"10" momentarily, indicating 10MHz
"130" momentarily, indicating 10.130MHz
"30.5" permanently, indicating the frequency is 10.130.5

What may be confusing is to see the display permanently on "30.5" when the frequency is actually 10.130.5, but that was the only way they could give you all the digits.

The calibration process lets you tune in a signal on a known frequency and then adjust the display for the correct read-out. The processor remembers separately for each band what "offset" is needed to put the display correct. The processor actually counts just the VFO frequency, but that "offset" allows it to compensate for any errors in the VFO, the BFO, or the Band heterodyne oscillators.

The only "build option" I'm aware of is to set the VFO range to 80kHz or 150kHz by substituting a different capacitor; so you could trade more bandspread for less coverage if that was your preference.

Hope that helps some.

Steve G3TXQ
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M0JHA
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Posts: 646




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« Reply #10 on: May 11, 2010, 02:04:52 PM »

hi steve, im definantly getting

"10"
"038"
"38.4"

i then have to run up the vfo to the UK allocation ..

looking at the board construction guide it states for the lower band edge of 10.000 mhz  X3B xtal is to be fitted ( 18.000 MHz)

 and for a higher band edge of 10.100 X3A   (18.100 MHz) xtal to be fitted ..

i looked on the board and infact the 1800 MHz xtal has been fitted.

i e mailed Elecraft and gary kindly explained it to me .. the vfo range is determined by the vfo capacitor C2 at a value of 68pf 120pf giving a range of between 80 and 150 kHz..

to get a low band edge of 10.100 i need to change the pre mix xtal from the fitted 18.000 to the supplied 18.100 kHz..

i think it was intentional from the builder as i can get onto the ssb portion of 40m and to around 14.165 on 20m and roughly the same on 15m so it looks like it may be a case of just getting as much band coverage as possible whether it could be used to tx or not..

i may switch xtals just so i dont have to keep running up the vfo when switching to 30m .. not a huge problem but a bit annoying ..

im sure if i look the vfo  cap will be of the higher value..

like i say its not a problem as long as i know what it is , the rig is nice but it has had me a little confused as im not a manual reader if i can help it.. im aplug it in and see what happens.. not always a good thing..

cheers again steve .. just need some good weather now to go and play with it outdoors..

billy
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G3TXQ
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« Reply #11 on: May 11, 2010, 02:55:51 PM »

Billy,

Yep - now it all comes back to me. Shows how bad my memory is because I must have made the Crystal choice when I built my 4-band filter board !!!

73,
Steve G3TXQ
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AD6KA
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Posts: 2238




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« Reply #12 on: May 16, 2010, 02:23:02 PM »

Quote
yes got the manual but that passage confused me..

I may be preaching to the choir but just want to make sure:

If the manual was downloaded, make certain that it matches
the Build Version of your kit and the kit Serial Number coverage range.

You might also want to go the Elecraft site and look for
K1 Application Notes, Builders Alerts, Mods, **Manual Errata Sheets**
and firmware upgrades.

http://www.elecraft.com/index.htm

An improperly aligned SWR/PWR detection circuit on the ATU
may be folding back the power out, perhaps? Maybe a redo is
in order, it's an easy one. One thing I've done with some of the
variable resistor trimmers in transceiver kits (especially PA bias adjustment)
is to replace those finicky one turn trimmers with 10 turn trimmers.
Most of the replacement trimmers have the leads aligned to physically replace
the single-turns exactly, but *read the schematics and trimmer pinouts carefully*
first.

73, Ken  AD6KA
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M0JHA
Member

Posts: 646




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« Reply #13 on: May 16, 2010, 02:52:34 PM »

cheers for the reply ken, its the original build manual from the original builder, all checked off etc as he went through the build..

theres a few bugs with it , mainly power issues not seeming to be steady , they can drop quite a lot as i go down the band unless i do a re tune , sometimes the power setting is saying 2 watts for example yet it may be putting out 3 or 1 ,this can be sorted by doing a re tune but i may not always be using the tuner..

i think its slightly off freq also
i think i will have to spend a night and re align it just to be sure..

billy
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AD6KA
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Posts: 2238




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« Reply #14 on: May 19, 2010, 08:07:09 PM »

Hey Billy:

Before you re-align everything, take a good close look at
torroid transformers T3 and T4 in the PA stage, especially T3.
I have rewound T3 on two K1's for an extra watt or two.

They must be wound very well, and exactly as in the manual,
especially T3. Also check the underside of the board to make
sure that all the enamel was properly taken off the wire
when it was soldered to the board. If the colored wire
looks like it is sitting in a pool of solder, its probably making
a poor connection. You can check this with a DMM to the
other end of the lead.

Also on T3 sometimes the red primary is just fine and wound well
all around the core as instructed, but the green wire
4 turn secondary is wound too narrow or not interleaved, not allowing
for good transfer of RF from the driver to the final PA device.

What I do on K1's and K2's for the flat torroid transformers
in the PA stage is to actually use 3/32" double backed foam to mount
them to the PC board. More for K2's on 10,12,15m is keeping
it from RF coupling to the PC board, but also allows some winding
tricks for the secondary (on the K1 too)

It sounds harder and more complicated than it is, wish I had a photo.
Probably a good visual and continuity inspection should be fine.
Actually, I think that Elecraft should have used a binocular core
there instead of a toroid. MUCH eaier and MUCH, much
more efficient.
good luck es 73, Ken AD6KA
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