Gday all,
Ive been playing with a elecraft k3 (with internal 2M).
Im finding the 2m stability awful! (audible drift on ssb!!!) I thinking of putting a murata style crystal heater on the 116mhz? crystal to improve the drift.
I wonder if anybody has tried this or has a better solution?
cheers, Graham VK3XDK
Elecraft k3 internal 2m
Re: Elecraft k3 internal 2m
Yes, Graham, I've used Murata crystal heaters on all my transverters from 144MHz to 10GHz. They work rather well, especially of the crystal is specified appropriately (50 deg. C, from memory). I've also retro-fitted them to the reference oscillators in some of my rigs where practical.
A couple of hints to get the best results: Choose crystals with wire leads, not the thicker pins, and solder the crystal such that its case is well clear of the pc board. This is to minimise heat transfer to the board. Five mm clearance is sufficient. Also, make a thermal enclosure for the crystal/heater assembly from a small block of packing foam. This minimises thermal drift from drafts and convection within the equipment enclosure. Of course, the supply voltage to the heater should be regulated. I generally use a 7808 regulator for this.
Chas
VK3PY
A couple of hints to get the best results: Choose crystals with wire leads, not the thicker pins, and solder the crystal such that its case is well clear of the pc board. This is to minimise heat transfer to the board. Five mm clearance is sufficient. Also, make a thermal enclosure for the crystal/heater assembly from a small block of packing foam. This minimises thermal drift from drafts and convection within the equipment enclosure. Of course, the supply voltage to the heater should be regulated. I generally use a 7808 regulator for this.
Chas
VK3PY
-
VK3XDK
Re: Elecraft k3 internal 2m
Elecraft have now released a locking module, to lock the internal 2m transverter to the radio's main oscillator (which is fairly stable)
Much better!!
cheers, Graham VK3XDK
Much better!!
cheers, Graham VK3XDK
-
VK4DD
Re: Elecraft k3 internal 2m
Hi,
There is a temperarture sensitive resitor connected to the varicap which Elecraft uses to compensate for the drift when the transverter gets warm (when transmitting).
I get the best results with a xtal heater and removing the varicap and disabling the temp sensitive resistor. A new capacitor needs to be fitted to get the oscillator resonating again with out the varicap.(I use the same heater chas refers too). In my case 8.2pf worked but that may vary with other transverters. This mod is not approved by Elecraft and will void your warranty.
Please note that when you remove the varicap, the new freq stability accessory from Elecraft will not work for you!
You also may want to keep the Xtal heater on even when the rig is powered.
In this way the stability will be better when you switch the rig on.
All above is experimental and should not be preformed unless you accept the risks of no warranty or a faulty
Proceed on your own risk! If you choose to do so.
I haven't got the new frequency accessory so I don't know how that preforms.
73 Ron.
There is a temperarture sensitive resitor connected to the varicap which Elecraft uses to compensate for the drift when the transverter gets warm (when transmitting).
I get the best results with a xtal heater and removing the varicap and disabling the temp sensitive resistor. A new capacitor needs to be fitted to get the oscillator resonating again with out the varicap.(I use the same heater chas refers too). In my case 8.2pf worked but that may vary with other transverters. This mod is not approved by Elecraft and will void your warranty.
Please note that when you remove the varicap, the new freq stability accessory from Elecraft will not work for you!
You also may want to keep the Xtal heater on even when the rig is powered.
In this way the stability will be better when you switch the rig on.
All above is experimental and should not be preformed unless you accept the risks of no warranty or a faulty
Proceed on your own risk! If you choose to do so.
I haven't got the new frequency accessory so I don't know how that preforms.
73 Ron.