Notes from 2009 Dayton Hamvention®. Based on conversations with users, here is a list of the most frequent requested custom features and topics of interest.

1. TCXO (Temperature Compensated Crystal Oscillator) option. I have sold all the C/W TCXOs and am investigating other options. Contact WA1FFL for latest details.

2. Band-limited version. I can ship a VFO software version that only covers a portion of
the HF band (i.e., 1.8-2.0 MHz, or the like). Reverse tuning (5.5-5.0 MHz, for example) is also available.

3. Frequency Step Word Truncation Effects. It turns out that, if a DDS clock
frequency of 134.217728 MHz is used (rather than the standard 150 MHz oscillator that I ship), the step
constants come out to be perfect integers. Then there is no finite-word or truncation error (which is
normally so small with the fixed 150 MHz clock that it is unnoticeable to most users). This clock oscillator
(134.217728) is not shipped in the standard kit because not everyone has a frequency counter or the
ability to trim it to this close precision. K2AOP’s voltage-controlled oscillator circuit (see application
note on this site) using an International Crystal IC1100FRSV2 voltage controlled oscillator, set for this
frequency using a trimpot, makes it possible to set this up. I have the VFO software program for this
clock frequency if anyone wishes to explore this option. Thanks to John Clark and Mitchell Lee for
encouraging me to investigate this.

4. Non-Detente Shaft Encoders. I have found two excellent ones made by Bourns, part numbers EM14A0D-24-L008N, and EM14A0D-24-L032N, both available for about $18.00 from Mouser Electronics. Be careful of the small pins- I used #24 solid wire to hook these up, bending them at right angles (the middle two are not used).

5. Clock error. With a 50 ppm clock oscillator (i.e., standard 150 MHz Connor-Winfield unit) you
will typically measure about 30 Hz/MHz step error in the 1 MHz steps. This is why I encourage users to
set up sub-bands in the flash memory and calibrate those bands individually. If you stay within the sub-
band after calibration, errors of less than 10 Hz. are typical.

Hope to see you in 2012 at the show. I appreciate all of your
feedback. Inquires are welcome at: