North America microwaves records and DX

By: Michel Vonlanthen HB9AFO

 

2002.3.11

11,4 km on 241 GHz WA1ZMS/4 + W4WWQ NEW WORLD RECORD

Photos:

I'd like to give the very latest update on our efforts at 241GHz beacuse some cold and dry WX again came our way. On March 11th, 2002 at 02:25z WA1ZMS/4 worked W4WWQ over  a new distance of 11.4km.

The details are:

I'd love to claim 13km, but I know the point to point distance is correct and is really the true distance.

WX at time of QSO:

Temp: 5.6C


I can honestly say that this looks like the limit of what we can do for DX with the gear I have without a major re-design. (ie: more power, bigger dish ant, new RX harmonic mixer, etc.) With spring just around the corner, it's unlikely we'll have much more in the way of cold WX. I'd like to thank Pete, W4WWQ for going out again in the cold at night and for Dave, KD4EMU for going roving with me. 

Brian, WA1ZMS/4

2002.03.01

I'd like to give an update on our efforts at 322GHz:

On March 1st, 2002 at 02:25z WA1ZMS/4 worked W4WWQ over a new distance of .5km.

The details are:

WA1ZMS/4 37-21-24N 79-10-31W FM07ji,  W4WWQ 37-21-14N 79-10-15W FM07ji, Mode used was FSK CW and gear is the same equipment that's been used of late for the 241GHz QSOs. (phase locked Gunns driving power multipliers)

WX at time of QSO:

An audio file is posted at: http://www.mgef.org/zms_322.htm

We tried a 1km path but just did not have enough margin. We'd need 6dB more for the distance and then an additional 
2.2dB for atmospheric loss at the time of the QSO for a total of 8.2dB and that was just not to be.

I know for some people, even 0.5km is not real DX, but I felt since we did 10 times the distance we did last December that
it was worth mentioning, and we are talking 322GHz here.

In other news, we did a one way QSO at 13km on 241GHz but not two-way. (very disappointing!!!) Maybe next time.

Brian, WA1ZMS/4

2002.03.01

47 GHz: 176 km W0EOM + KF6KVG
75 GHz: 176 km W0EOM/AD6FP + KF6KVG   NEW WORLD RECORD

On Friday, March 1, we completed several QSOs that we believe set a new North American record on 47 GHz and a new world record on 75
GHz.  

At 12:30pm PST W0EOM completed a QSO from Mt. St. Helena California (CM88QQ) to KF6KVG on Mt. Umunhum (CM97AE) on 47.040 GHz. Signal levels were 20+ db out of the noise. Several minutes later W0EOM and AD6FP both completed QSOs from Mt. St. Helena to KF6KVG on Mt. Umunhum on 75.600 GHz. Once again signal levels were 20+ db out of the noise. The grid to grid distance from CM88QQ to CM97AE is calculated as 176.75 Km.

After several false starts in arranging a record attempt Will W0EOM finally got everyone to agree to go out on Friday March 1. Will and
Gary AD6FP went to Mt. St. Helena, Bob KF6KVG went to Mt. Umunhum and Lars AA6IW was in Los Altos Hills. Previous tests indicated we
might have difficulty with paths longer than 160 Km on 75 GHz so Lars was positioned 156 Km from the Mt. St. Helena end.

Arriving at Mt. St. Helena Will and Gary found the traditional operating spot in disarray. High winds the previous evening had
caused a tower to fall partially destroying the wooden deck that is usually used by the local microwave crowd. The winds were also
still pretty high, estimated at 35 to 40 mph. After some exploration we were able to find a sheltered spot out of the wind and set up the radios.

A quick try of the 10 GHz radio resulted in nothing heard from the local beacon or Lars high power transmitter so we concluded the
transverter had failed. We were hoping to use the 10 GHz signals to determine bearings to Mt. Umunum so when the radio failed things
were looking dismal. Luckily Will was able to find the signal from Bob on 47 GHz with a bit of panning of the dish. Once peaked up on
47 GHz we had a good optical target to use to sight the 75 GHz dishes.

The 47 GHz signal levels were sufficient to allow Bob to complete the exchange using NBFM rather than CW. After aligning the 75 GHz
dishes on the same heading as the 47 GHz dish the 75 GHz signal from Bob was quickly located on the Mt. St. Helena end. To our surprise
the 75 GHz signal level was as good as the 47 GHz level. The two 75 GHz contacts were quickly completed from both W0EOM and AD6FP to
KF6KVG. The 75 GHz signal from Mt. Umunhum peaked 23 db out of the noise with 6-8 db fades.

After working Bob on 75 GHz Will and Gary repositioned their dishes and worked Lars AA6IW on 75 GHz at 156 Km distance (this would have
previously been a 1 km increase in the 75 GHz world record). Signal levels from Lars on the 156 km path were comparable but slightly
less than the levels from Bob on a 176 km path.

The equipment used at each station is as follows:

W0EOM 47 GHz: 60 mw xmit power, 2' cassegrain dish, 4db NF rcv. 76 GHz: 8 mw xmit power, 18" cassegrain dish, 15 db NF rcv.
KF6KVG 47 GHz: >20 dbm xmit power, 2' prime focus dish, 4db NF rcv. 76 GHz: 10 mw xmit power, 1' prime focus dish, 15 db NF rcv.
AD6FP 76 GHz: 4 mw xmit power, 3' cassegrain dish, 15 db NF rcv. 
AA6IW 76 GHz: 4 mw xmit power, 18" cassegrain dish, 15 db NF rcv.
All the radios use LOs that are locked to either precision OCXOs or Rubidiums.

Weather conditions were very favorable for mm-wave propagation:

18% to 26% rel. humidity along the path.
40 to 65 degree F temperatures

On the way down Mt. St. Helena we could easily see the snow capped peaks of the Sierras over 150 miles away. The unusually low humdity
as well as the clear atmospheric conditions were major factors in making QSOs on this record path.

Will W0EOM
Bob KF6KVG
Gary AD6FP

2002.02.23

241 GHz: 7.3 km WA1ZMS/4 + W4WWQ NEW WORLD RECORD 

I'd like to report what looks to be a new World, as well as North American DX record for the 241GHz band.

Earlier today, myself (WA1ZMS/4) and Pete, W4WWQ set several new DX records for the band. We first worked over a distance of 3.8km, then 6.1km, and finally 7.3km at which point we ran out of signal margin for the WX conditions at the time. (Former World record was 2km by DB6NT and NA record was 1km by W2SZ/4)

The details of the claimed 7.3km record are as follows:

Feb 23, 2002 19:45z
WA1ZMS/4 located at 37-22-56N 79-14-43W (FM07ji)
W4WWQ/4 located at 37-21-13N 79-10-15W (FM07ji)
a location to location distance of 7.3km

WX at time of QSO was:
Temperature 8.3 degs C
Dew Point -2.8 degs C
Relative Humidity 46%
Pressure 1017 millibars
Calculated loss of 1.70 dB/km

Photos and an audio file will be forthcoming and should be posted on www.mgef.org within the next few days.

The stations used are improved versions of the ones used in Dec of 2001 for the former North American DX record. The improvements involved the phase locking of the 80.6GHz Gunn sources back to homebrew ovenized crystal oscillators. This allowed the use of FSK keyed CW and the use of a narrow band receiver IF. The IF receivers were an Icom R-7000 and a Yeasu FT-817. The IF freq was 439.7MHz +/- some frequency drift. The ovenized crystal oscillator frequency is effectively multiplied some 2220 times to get to 241GHz! The stations were able to maintain better than 2 KHz stability over several minutes. Frequency drift was still a problem however and with weak signals several repeats of the exchanges were needed to complete the 6.1 and 7.3km QSOs. If dryer WX comes along, better DX may be achieved.

I'd like to thank Pete, W4WWQ for his roving efforts and to WA4RTS for the loan of an R-7000 in place of him being able to assist with this weekend's QSOs, and to Jeffrey Hesler of VDI. 
73,
Brian, WA1ZMS/4

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