Frequently Asked Questions

Q. My bag of 8.000 mhz crystals (80 meter kit) has a tag inside with the number 7660. What is this number and why is it important for me to make note of it in my manual?

A. The crystals have been matched for optimum performance in the receive crystal filter circuit. They are typically less than 25 hz apart and have an insertion loss of less than 1.5 db each. The numbers are the last four significant figures so a 7660 number means the frequency is 7.997,660 mhz which is only 340 hz lower than the stamped 8.000 mhz on the crystals, well within the performance curve. Should you find a defective crystal we can ship you one that's close to the matched ones you have.


Q. I have a bunch of extra capacitors left over. What are they for?

A. Since your normal receive span is only 35 khz, you can select what part of the band you wish to work by noting the spans shown on the bottom right of page 13 in the manual. We recommend that you place any extra capacitors in one of the zip loc bags that your components came in and tape it to the inside of your manual should you decide to move the frequency span.


Q. I'd like to work a larger span of frequencies. What can I do?

A. You can place a 150 pf NPO temperature stable capacitor across C8, preferably on the bottom of the board. This will allow you to span about 100 khz. You may wish to replace the 100 k tuning pot with a 10 turn 100 k pot to give you a finer tuning range.


Q. I want to put a digital display on my transceiver. Where can I pick off the frequency for the counter?

A. You can try the hot end of R17 or Pin 6 of U1. Keep in mind that the input load from the counter may shift the VCO down slightly depending upon the capacitive loading of the counter and your input wire. This should not be a problem because the display will still show actual frequency but you may wish to change the value of C7 down a few picofarads if your trying to keep the range where you want it.

Update: I have found that Pin 7 of U1 is by far a better pick of point which will not alter the VCO.


Q. Who makes the best counter display for the ME series transceivers?

A. There are many DIY kits both LED and LCD and are available on many of the links shown on the "Links" page. Keep in mind the VCO is constant on both receive and transmit so all that's necessary is to program the offset IF which is different for each band. My personal preference is the 5 digit LED one from QRPGUYS.com Digital Dial Thru Hole for only $15 in kit form.


Q. Why are there substitutes for some of the parts used?

A. In keeping the cost of the kit down while keeping the quality high, we shop around for the best parts. Sometimes a different part number will be in the kit. Also there are those who purchase just the board and wish to use parts from their "junk box". Most parts aren't critical except for the mixer I.C.'s. For a more detailed list of substitutions check out the Substitution page.


Q. My manual is different than the one online. Why?

A. The online manuals have the latest changes, and corrections. Most changes are cosmetic, clarifications, or typos that have been fixed. Always refer to the latest online version for accurate and complete information. It is not our intention to make any circuitry changes without a major board revision. The current board is electrically the same as the legacy board made by the designer David Benson over 20 years ago.


Q. How much more power can I squeeze out of the ME40+ (or other bands)?

A. We recommend running between 1.5 and 2.0 watts. There have been reports of people tweaking as much as 3.5 to 4 watts output. We do not recommend any more than 2 watts out. The output transistor is very close to other parts on the circuitboard. Excessive RF will get into the QSK circuit, receive circuit and even the driver stage of the transmitter. This will cause instability and spurs up and down the band. You may notice this when you turn the drive pot up and hear a raspy noise or even the sidetone disappearing. The circuit was designed for up to 2 watts only. Also putting a heatsink on the output transistor just increases the RF radiation in the circuits around it.


Q. How can I accurately measure the RF output?

A. Midway recommends the QRPOmeter by NM0S. Can be ordered here: QRPOMETER Highly accurate digital wattmeter to 15 watts and internal switchable dummy load.