Manager


Manager - NA4M
Manager Notes
Reviews Home

Reviews For: ICOM CR-338 high stability crystal unit

Category: Transceivers: HF Amateur HF+6M+VHF+UHF models - non QRP <5W

eMail Subscription

Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted.
Review Summary For : ICOM CR-338 high stability crystal unit
Reviews: 4MSRP: 81.00
Description:
Optional CR-338 high stability crystal unit for high frequency stability of ± 0.5 ppm
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0045
W2SGM Rating: 2021-03-23
Frequency adjustment takes longer than installation Time Owned: 0 to 3 months.
Installed in an IC-718. I'm happy with the performance, and it's an inexpensive upgrade for this radio.

Like WI9NDY, I was also unable to find detailed installation instructions. The installation of the crystal itself was trivially easy: unplug and remove the PLL board, flip it over, remove the original crystal and solder this one on. There is "OPTION" as well as +/- printed on the board-- align it with the +/- on the underside of the CR-338.

In my case, I re-mounted the PLL but found the frequency too far off for the C16 adjustment to fix (C16 is the reference frequency pre-setting trim pot on the underside of the PLL, which is the exposed side when it is mounted in the radio). I had to unmount the PLL and run the radio while carefully holding the PLL and adjusting L4 (reference frequency adjustment, on the top of the PLL board) to get close, then use C16 for more precise adjustment. Use a non-magnetic flathead, otherwise you won't be able to see the result of your adjustment until you remove the screwdriver from the pot.

I didn't have a frequency counter or signal generator like the service manual recommends for adjustment, so if you don't either, you can use another method. Make sure the crystal is fully heated (~10 minutes). Tune to 4.999.000 MHz and set the radio to USB. You will hear a tone from WWVH that should be 1000 Hz. Use an audio tone generator on your phone or computer and adjust L4 until you hear the beat frequency get within 1-2 Hz. The closer you can get it, the better. Then re-mount the PLL and do it once more with C16.

Your radio will now be more precise in frequency than before, but not necessarily more accurate until you can get a proper signal generator to re-calibrate. But at least your radio will be stable, and accuracy within the error of the audio tone generator you used should be good enough for most purposes.
K6SDW Rating: 2007-02-19
Dead on.... Time Owned: 0 to 3 months.
Just installed this on my ICOM 746PRO (which didn't really need the high stability xtal) and adjusted dead on with WWV.

Easy, straight forward install .....

Cheers All!
KP4DAC Rating: 2007-02-19
Works Great in Planes Time Owned: more than 12 months.
I installed this on my three Icom 706MKIIG and it holds the frequency down to the cycle when compared against WWV. I have the 706s installed out of the aircraft cabin environment where temperatures run into -20F at 25,000 feet and the CR-338 holds the frequency right on. The 706 takes less than a minute to stabilize on frequency. The CR-338 is a nust for wide temperature range environment
WI9NDY Rating: 2006-01-13
Icom CR338 TCXO Upgrade Time Owned: 0 to 3 months.
There is very little information on this option so I thought I would share. I installed this option into an Icom IC-718 transceiver. The IC-718 manual gives clear instructions for the installation. Once you have the bottom of the radio removed the circuit board is accessible. One word of caution, the ribbon cables are fragile so take care in removing and re-inserting them. Once the board is removed unsoldering the crystal is easy using a low wattage iron and solder wick. You have to remove excess solder from the new mounting holes and the only tricky part is the ground plane hole. Once this is done the CR338 can be soldered in. After the board is reinstalled the frequency is adjusted with C-16. This must be done as the frequency will be off. It is best to let the rig warm up for a period of time (I waited for one hour). Total time was about one hour of work to install the option.

73 de WI9NDY