I am Michel Spelier, ON7EH (vanity call: OP3T) and 3d generation full class ham
family. My father was ON5SP, Roland and my granny, Leo ON4SP, 9Q5EH and EA5ASN,
resp. I’m living close to Brussels Airport in a suburban lot, with open fields behind the
garden, from friendly farmers.
I passed the ham exam in 1979 (when on secondary school) and mainly did weak
signal operation on 144MHz. Finally, after 30 years, I got my 2m DXCC, quickly followed by DXCC on 6m and topband. Most operation on 2m was done from my parent’s QTH from a tiny 7m by 7m garden!
In 1992, I participated with ON5FF (now D4FF) to the probably most successful 2m CW EME (and all-mode satellite) expedition to The Gambia, as C53GS. There, an Eimac 3CPX800 PA with a toroid transformer in a shoe-box and 8x K1FO 12-element yagies were used.
At my new QTH (°2003) in the same town, I can benefit from a larger garden with
massive ground gain to moonrise, which I’ve put to good use on 2m and 6m single
antenna EME, resulting in several firsts from Belgium on 144MHz.
Over the years, a Norcal40A, Elecraft K2, K3, KAT500 and KPA500 were built. Last year, 2024, the CQ 160m WW contest was won in the single op/ low power/non-assisted category, with the big help of a K3+KAT500, upgraded with a KSYN3A.
Later that year, after a family holiday in Toscane-Italy, I collected K4D #1423 with KPOD from Lutz Electronics in HB9, on our way home. This years 2025 CQ160m contest edition, I ended in second place, after XE2X, but still first European, before some top operators from the Balcan.
The K4D and K-Pod were instrumental in this effort. The learning period was short due to already knowing the K3 through and through and by studying the available reading material on the Elecraft-K4 groups.io reflector and attending the K4 zoom sessions, patiently lead by N6TV, Bob and Carl, K8NU.
The 17m high inv L Tx antenna is based on stacked long 3” KLM-booms.
On the Rx-side, a 4-direction short Beverage system was used to discriminate the callers and provide the necessary low noise reception. DR+ and the internal PRE2 are within my standard Rx-settings during low band contests.
In what follows, I describe the multiple hurdles, I had to overcome to become active on the (new) 8m band (40MHz) in Belgium with the K4D and KAT500.
Hurdle 1: obtaing the temporary 8m license in ON
Not quite 12 hours after my request, the regulator emailed my temporary 8m band
license. Limitations: 5W ERP, secondary user; shared spectrum with ISM-appliances (industrial, scientific and medical), A1A/F3E/J2D/J2B/J3E modes allowed, 40.66-40.69MHz, keeping a logbook. Valid till EOY 2025.
Hurdle 2: the Elecraft K4D and KAT500
When trying to send a CW carrier on 40.67MHz, I got ER60 (attempt to tx outside the band edges). A Google search ended on the K4-reflector and revealed a solution to be existing: I had to send a “MARS” frequency extension request to Elecraft Support. The “TX Limit Unlock (MARS) patch” arrived promptly, its installation and make function were trivial.
Hurdle 3: checking the harmonic rejection of the combo K4D (and KAT500)
A Keysight Fieldfox SA was put to good use to measure the (conducted) K4D
harmonic rejection through 60dB of attenuation, at 3 different power settings 5, 10
and 20W.
Below the plot for 5W K4D output power. (power set through the TRX output power knob) Higher than second harmonic products were always below -60dBc. (not
shown) At 10 and 20W K4D output powers, the 2nd harmonic were -39 and -48dBc resp.
For the combo K4D+KAT500, which I hoped would improve the harmonic
rejection, I used the groundplane antenna installed on a solid tripod some 15m away
from the house in the garden. The SA, with a fully extracted telescopic whip, was safely installed inside the house.
The screenshot below shows the values after tuning the KAT500 with 5W input power:
OTA (over-the-air) values obtained for 10 and 20W were -49 and -44dBc.
I did not retune the KAT500 for the higher power settings, which could have improved
the final values.
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Subsequently, Wayne, N6KR, convinced me this would be good enough for the experimental character of the 8m license, so I pursued without extra filtering… |
Hurdle 4: the Procom GP40 triple leg ground plane
 |
For long, I have had (undocumented) fiberglass At 3.5m height on a solid tripod, the GP return loss is 30m Ecoflex 10 are hookup up to the K4D in the cellar. Considering the cable losses, I can increase my Tx power to 6W RF to reach the 5W ERP at the antenna. |
The fifth and last hurdle with reward: Es opening on 8m
After the measurement session, WSJT-X was called up with the K4D-Rx left on 40.680M.
I had been doing FT8 before, but even then was surprised to see that the above frequency was already indicated on the FT8-GUI. No activity was visible on the bandscope.
Returning some time later, I saw signals on the bandscope and decodes on the PC.
Eureka!
It is nice to see the K4D-Rx noise floor drop with every increasing PREx activation, lowering the Rx’s noise figure and increasing the K4D’s sensitivity. I left it at PRE3.
Notes:
- The antenna names (invL) have not been changed to reflect the new antenna
situation - The TX-menu was not clicked away.
- Known bug: on my first transmission, the ALC marker in data mode stays in the
corner of the scale. Only the following transmission could I tune for 5 marks to
correctly set the audio level for data.
Following were several QSO’s within Europe, with ODX IT9 at 1600+ km and 6 DXCC.
“Amazing this wonder of wireless QRP with basic antennas.”
73 de Michel, ON7EH OP3T
Runner-up 2025 CQ 160m CW single op/ low power/non-assisted