Making Weak Signal QSO's On 630m

As much as I love CW and try and promote its use on 630m, one cannot deny the growing interest and use of the WSPR mode on our newest ham band.



Its ability to dig deep into the noise and successfully decode signals as weak as -30db makes it an attractive method of watching the night-to-night and hour-to-hour propagation magic.

One only needs to check the number of stations logged into the WSPRnet Activity-page, uploading 630m spots each night ... a typical evening will see 60-80 calls listed.

The main problem with WSPR is that it's a one-way, beacon-only mode and it's not possible to utilize it for a valid two-way contact. It's nice to know that station 'A' is able to hear station 'B', and vice-versa, but the only way for both stations to know this is for them to both be monitoring the internet uploads ... if both stations were able to confirm their respective receptions all via radio, then a two-way contact could be claimed. Thankfully, there is another mode that solves this dilemma, without internet intervention and that's JT9.

JT9, developed by K1JT, is a spin off from his JT65 weak signal QSO-mode software developed for EME. JT9 has been tailored for the noisier HF and MF bands and is apparently, about 2db more sensitive than JT65. In the past, I have made several single-yagi EME contacts on 2m using JT65, with many of these QSO's being in the -27 to -29 db range. This would suggest that 630m JT9 contacts could be made at signal levels as weak as -30db!

A recent "630m Activity Weekend" in Europe turned out be a "630m JT9 QSO Party" with dozens of Europeans working each other throughout the event using this weak signal mode with great success. It looks very much as if JT9 may now be the go-to mode for two-way work on 630m when, as is often the case, signals can be easily seen on a visual waterfall display, but are too weak to be heard on CW.

DC1RJJ's 630m JT9 action courtesy: KB5NJD

On this side of the Atlantic, recent JT9 contacts have been made between several of the U.S. experimental stations. WH2XCR in Hawaii (K9FD/KH6) and WG2XIQ in Texas (KB5NJD) worked on Dec 9th, while WH2XGP (W7IUV), WG2XSV (W0YSE/7) and others have been exploiting the power of JT9 to work around the country.

Such has been the case for me recently, with the arrival of VE3OT on 630m. Since beginning his nightly slow speed CW, QRSS6 beaconing, his signals have been easily visible here every night but only strong enough to hear aurally, on two occasions.  It is likely that we could work each other fairly routinely on JT9 but will need to wait for very good conditions to work on CW.

The good thing about modes such as WSPR and JT9 is that they can be used without the need for linear amplifiers in the PA ... class D or E amplifiers, fairly universal in the LF/MF world, can be employed. The most popular route at present seems to be via a homebrew  transverter that will allow the use of the station's main HF transceiver (using the tone-generating JT9 / WSPR software) to generate the required 630m RF.

I've been looking for a new radio workbench project to catch my interest and building a 630m transmitting converter is beginning to look more attractive, now that we have another DX target in VE3 land ... of course, if and when the U.S.A. gets the band, there will be an entire new crew of stations spread across the continent to keep the transverter busy!

The 1st Annual Midwinter 630m Activity Weekend

Following late fall's very successful 630m Activity / CW Crossband Weekend in November, several enquiries were soon received asking "when's the next one?" I'm happy to announce that the 'next one' will be held on the first weekend of February and will follow a similar format. 

Here is the formal press release describing the event published in the ARRL News:


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US and Canadian radio amateurs and experimenters will join forces in February for the first Midwinter 630 Meter Activity Weekend. The event will get under way on February 6 at 0000 UTC (Friday, February 5, in US time zones) and run through 2359 UTC on February 7.

“This event is being undertaken because of the new and quickly growing interest in present 630 meter activities, both in the US and Canada,” said  ARRL 600 Meter Experimental Group (WD2XSH) Experiment Coordinator Fritz Raab, W1FR. “Much of the interest is in response to the strong likelihood of US amateurs receiving access to the band in the near future, while Canadian hams are eager to learn more about the present level of Amateur Radio activity on their newest ham band.” The activity weekend comes on the heels of a special event operation over the November 13-14 weekend that included participation by US and Canadian radio amateurs.and the Maritime Radio Historical Society (MRHS).

Raab said the two activity nights will offer interested amateurs in both countries an opportunity to experience the 630 meter band and, through cross-band activity with Canadian amateurs, to take part in activity in the MF spectrum. “Our hope is to see this activity become an annual operating event, to be held very winter on the 630 meter band,” Raab said. “For those who may be building for future 630 meter operation, this event will provide an opportunity to test your ‘receive’ capabilities on MF.”

Operation will be from 472 kHz to 479kHz in various modes. The two-way crossband work will be undertaken by several Canadian stations, all on CW. Canadians will operate on a schedule and listen for callers on specific QSX frequencies in the US ham allocations.

Station: VO1NA (Joe) GN37 Torbay, Newfoundland
Time: 2130Z - 0130Z both Friday night (Feb 5 - 6Z) / Saturday night (Feb 6 - 7Z) plus QRSS3 / 12 WPM Beacon from 0130 – 1000Z
TX Frequency: 477.7 kHz
RX (QSX) Frequency: 3562 kHz

Station: VE7SL (Steve) CN88 Mayne Island, B.C.
Time: 0200Z - 0700Z both Friday night (Feb 6Z) / Saturday night (Feb 7Z)
TX Frequency: 473.0 kHz
RX (QSX) Frequency: 3566 / 7066 kHz

Station: VE7BDQ (John) CN89 Delta, B.C.
Time: 0330Z - 0700Z both Friday night (Feb 6Z) / Saturday night (Feb 7Z)
TX Frequency: 474.0 kHz
RX (QSX) Frequency: 3555 kHz

Station: VA7MM (Mark) CN89 Coquitlam, B.C.
Time: 0500Z - 0700Z Friday night (Feb 6Z)
          0400Z - 0800Z Saturday night (Feb 7Z)
TX Frequency: 475.0 kHz
RX (QSX) Frequency: 1801 kHz / 3574 kHz / 7062 kHz

Station: VE7CNF (Toby) CN89 Burnaby, B.C.
Time: 0300Z - 0700Z both Friday night (Feb 6Z) / Saturday night (Feb 7Z)
TX Frequency: 476.5 kHz
RX (QSX) Frequency: 1836 kHz / 3558 kHz / 7031 kHz

Station: VE3OT (Mitch) EN92 London, ON.
Time: 0000Z - 0400Z both Friday night (Feb 6Z) / Saturday night (Feb 7Z)
TX Frequency: 477.0 kHz
RX (QSX) Frequency: 3563 kHz / 7058 kHz

Several US Experimental stations also will be in operation throughout the band, in two-way QSO mode with each other, using CW, PSK31, JT9, and QRSS modes. Some stations will also use WSPR and QRSS CW beacon modes.

“The success of this event largely depends upon the participation of as many amateurs as possible,” Raab said. “We hope that you can find a few hours to participate in this unique midwinter event.” Submit reception reports via e-mail to the respective operators or via the ARRL 600 Meter Experiment website.
   

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Hopefully you will be able to participate in the crossband activity by being able to listen on 630m and then able to switch over to HF to transmit. This could involve the use of a separate receiver / transmitter or can often be easily implemented via your transceiver's 'A/B' switch.

No antenna for receiving on 630m? Surprisingly good results can often be had by using a low band wire antenna such as a dipole or inverted-L for listening on 630m ... the antenna does not necessarily need to be resonant. In fact, often times, a non-resonant receiving antenna can provide a better overall S/N ratio than one which is resonant, as these often gather more noise along with signals.

You may want to experiment before hand by listening to many of the numerous U.S. experimental stations operating nightly, mostly in the WSPR mode, between 475.6 and 475.8kHz. Most operators provide a CW identifier following their WSPR transmission but a better way to decode these signals is by installing the latest WSPR software, WSJT-X (freeware), at K1JT's website here. The software works extremely well and is easy to install and get working. If you set the software to 'upload spots', you can share your nightly catches with dozens of other listeners throughout the continent on the WSPRnet website.

courtesy: KB5NJD's 630m Daily Blog

I'll be sending out a few more reminders as the 630m Activity Weekend gets closer but please mark your calendars and make a date to participate, by either sending in your 'heard' reports or by getting on-the-air and working some of the Canadian crossbanders.

Another New VE on 630m!

courtesy: https://www.google.ca/maps

 Another new Canadian station has been activated on 630m ... VE3OT, Mitch, in London, Ontario.




For many years, Mitch has been running his QRSS 'MP' beacon on 2200m, using a large E-W wire loop and about 200 watts.

The move to 630m uses the same transmitter with a retuned loop and new output LPF. Although the antenna tuner still needs a capacitor swap and a new toroid to perfectly resonate the loop, Mitch has been getting many good 'audible' reports from eastern stations as well as from the central states and as far south as Texas.

Present testing is in the QRSS6 CW mode on 475.0 kHz. Unfortunately, since moving up to 630m, E-W propagation has been hit and miss and although I can copy his QRSS6 CW signal, I have not had aural copy as of yet ... maybe tonight.

courtesy: http://www.solarham.net/

Hopefully when the geomagnetic field calms down again, Mitch can work some of the VE7's out this way on CW ... wouldn't that be a nice way to start the New Year!

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Another 630m CW crossband activity has been planned for early February and I will have more details shortly. If you missed the last event, here is another chance to get in on the two-way crossband fun ... please stay tuned!

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LED Lights In The Shack

Utilitech Pro Soft White LED Bulb

A recent posting by Phil, KO6BB, to Yahoo Group's ndblist, described his recent search for some LED lamps to replace the CFL's in his shack / radio workbench area. If you have been wondering how much RFI that LED lamps might be producing, you may find Phil's findings of some value.






"Recap  

I had a 60W equivalent CFL in the floor lamp directly over my operating position. I'd tried a 100W equiv one but it was extremely noisy! Also a couple CFLs in the ceiling lamp.

This is a floor lamp with a crookneck at the top and a triangular metal
shade reminiscent of the old style desk lamps, bulb is horiz to the
floor. I've used it for years and like it because it places the light
directly over the operating position work area (keyboard, radios etc).
The actual bulb was about 4.5 inches from the front of the Softrock SDR
receiver (in a plastic case), with the base of the lamp (where the
electronics are) about 7.5 inches (somebody asked about the distances).

This coupled a LOT of RFI directly into the SDR, visible on the
waterfall. For best results when recording and having the light on I'd
slip a 60W incandescent lamp in place of the CFL. The lamp is also
about 16 inches above the operating table, and when listening to ANY
portable radio on the table, if it was in the AM or Longwave band and
using the built in loopstick antenna, got a LOT of RFI from the lamp
(unless the lamp was off ;-)

So today I went down to Lowes (we have a Costco, but I don't have a
card) and looked at their LED lamp offerings. As I expected they had a
large variety of them, from a low cost 3 pack for ~$9.00 for 60W units
to about $18.00 or so each (Sylvania). From what I read here I wanted
to avoid the REALLY cheap ones as some reported them to be 'noisy'.
Also, I wanted to put a 75W equivalent unit in the one over the
operating position, and a pair of 100W equivalent units in the ceiling
lamp. All three had CFLs, and if I walked around the radio room with a
portable radio and the ceiling lamp on I could hear it's 'hash' anywhere
in the room. . .

The ones I settled on were a brand I'd never heard of, "UtiliTech Pro"
soft white, 75W for the bench and 2 100W ones for the ceiling. They
were what I'd call "mid-priced", $8.98 for the 75W and $9.98 for the
100W ones.

Specs:

75 W one draws 12W and gives 1100 Lumens.
100W one draws 16.5W and gives 1600 Lumens (the pair in the ceiling
should then be 3200 Lumens if I calculated right).

How low is the RFI to my Radios?

75W one over the bench:
NO trace from the lamp electronics visible in the SDR waterfall at
all. With a portable radio on the bench-top, NO audible RFI. Put a
portable radio up to the "bulb" part (light area) and with no station
tuned in can't hear ANY RFI. Move the portable to the base area of the
lamps there is SOME RFI, but I won't be putting the radio that close to
the lamp, move it a couple inches away and the noise disappears.

100W ones in the ceiling lamp, NO audible RFI in the portable when
walking around the room, RFI just barely perceptible right next to the
light wall switch that turns the lamp on, again, audible IF I put the
radio right up to the base of the lamps, not a likely real-world scenario!

Upshot? 

Based on the sample of three that I bought and the almost
non-existent RFI from them I'd consider the UtiliTech Pro lamps to be a
good product and suitable for use in the radio room. I consider them
good value for the ~$30.00 I spent for three."

I don't see these being sold here in Canada but I may be mistaken. If you have tested anything similar (other brands / models), please let me know and I will add it to Phil's helpful information.

KO6BB's website can be found here, along with some of his homebrew equipment.

GW3UEP 630m Transmitter Tweaks

DF8UO's GW3UEP 630m Tx

I recently received an interesting note from Daniel, DF8UO, describing his GW3UEP transmitter modifications:

Hi Steve,

I have seen on your Website, that you are also a MF/LF fan and builder of GW3UEP QTX. I build the version with 2 IRF540 as you proposed and the same version with 2 IRF630. As I bought some time ago a PSU with can be regulated from 1V to 60V and max 10A (it is a Manson HCS 3404) I made some measurements on both version. Find attached an Excel with the measurements I made, if you are interested in.

If you use the IRF540 version you can see that if the power exceeds 100 W, the efficiency goes down, as the IRF540 is only specified for 100V.

Currently I am using the IRF630 version running at 300W without problems.

From Daniel's test data, it looks as though the IRF540's are quite happy as long as you keep the transmitter at 100W or less ... anything higher would certainly benefit from the switch to IRF630's as the high efficiency is maintained at least to the 300W level. Something at this level would no doubt benefit from higher-voltage capacitors and heavier inductors as well as a little more heatsinking, enough to shed at least 25 watts of heat between the two FETs.

Daniel drives his amplifier with an Ultimate3, followed by a 10db attenuator, a squarer and into the totem pole driver stage. His own version uses toroidal inductors rather than the original air wound coils.

A pair of GW3UEP amplifiers using IRF630's at ~40V into a small power combiner, should provide ~550W of useful output at >90% efficiency ... more than enough power to do some serious work on 630m.