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Thursday, November 30, 2006



I like the valve tube ......

At the first of my Ham world it was really not easy to find components to build equipment.
As tubes, transformers, meters, CV’s coils, and lot of small spares parts absolutely needed for the construction. Many time I have modified, rebuilt more and more transformer for HV, filament heating, bias….., built CV’s, coils, rebuilt, calibrate meter’, etc….
So it was very funny! Despite dangerous problems with HV or others miscellaneous bad luck…
At the end of the construction, and when it was tuned, the extreme satisfaction was immeasurable!

***** I remember about a strange story ;-) happened in 1993… Further more of 10 month, I built my own EME station for 432 MHz.
It was done with homemade station as well as a transverter 28/432 MHz, Power amplifier 3X 2C39BA, 2 X 22el long yagi (DL6WU design), preamplifier (Dubus design), coaxial relay (Dubus design), and splitter (Dubus design).
I had installed my EME station outside the QRA like portable station in my compound.
So, near midnight, feverishly and anxious….when I heard my own CW signal with about 1s delay reception time and when I said a couple minutes after “Hello the moon”, I heard my voice, I was like a crazy monkey and I jumped around the station on the grass to shout “It’s work ! It’s work!”
My wife was afraid for short time Hi, Hi!!!

For the fun, the moon tracking was………(please don’t laugh) ;-) an aluminium pipe, 3 meter length between the 2 yagi’s…… see the moon through this !!!!
Unfortunately, I don’t make a lot of EME QSO, because my career was turn on the better way in Telecom, broadcast network in Canada, more often around the world and had not enough time to built or be quiet for QSO…
It is one of more unbelievable souvenir!


807: Used in 1971 for HF TX
QQE 06/40 used in 1977 for VHF amp. (Drived with Icom IC202)
4-250 used in 1980 for HF amplifier (2 tubes)
QB4 1100 used in 1983 HF amplifier (2 tubes)
4CX250 used in 1985/6 for VHF/UHF amplifier (1 tube) and 1993 (2 tubes).
2C39BA used in 1986/7 for UHF amplifier (3 tubes), SHF cavity amplifier (1 tube).
3CX3000A7 used in 1992 for HF amplifier.
TH308 used in 1992 for SHF cavity amplifier

Monday, November 06, 2006

CUSHCRAFT R7000 Prob/Repair

CUSHCRAFT - R7000 Prob and repair.

Hi Folks,
Not lucky with the first installation of Cuschraft R7000 in 9Q1 (Rep. Dem. of Congo)
After having received from Switzerland a second hand antenna Cuschraft R7000, I installed it but only the 18 MHz was operational.
I decided to see what happened with that while disassembling this antenna completely.

- The screws of fixings for all coils on the capacitor tubes were loosen.
- has the inside of the coils, two had a great deal of bites, spiders, etc amalgamated in the base of the coils.
- Big humidity inside the coil.
- Coil of 14 and 10 MHz burnt. (Due, no doubt about that for an elevated VSWR and a short circuit probably with the water, accumulated bites and nests of spiders)
- Internal capacity in the coil of the 21 MHz (small aluminum pipe in serial on the coil and isolated by Teflon) completely loosen, and electrical sparks, (rivet “pop” was deficient, no contact)
- The insulating part has the basis of the antenna (fiberglass) damaged behaving like a sponge.
- Water also goes back on the top of every pipe between the coils.

Repair and method used:
- disassemble every coil carefully.
- remove all screws and move carefully the alu. small loop of every coil inside the capacity trap.
- With a nylon hammer hit slightly on the tube dia. abt 2cm to remove them of the capacitor pipe.
it only holds by two struck points in the capacitor trap on the middle of the trap.
- clean correctly each coils, and every insulating PVC support of the coils.
- I removed the burnt plastic part of every coil PVC and added of the insulating joint in the cleaned holes. (Like same procedure with the dentist... hi)
- apply 2 layers of varnish to all coils.
- make a new small hole like 4 mm dia near the PVC to suppress the fixing with the screws for the coils.
Move the spire of the coil above the new hole that you made and fix it with aluminum. Rivets “pop”

- Put back the insulating joint on the top of the 3 trap protections rubber.
- add a sufficient quantity of amalgaming tape over it.
Every screw of fixing of the coils was blocked with nails varnish and some amalgaming tape has been added.
I put 3 layers of varnish on the insulating part in fiberglass (bottom of the antenna)

* The first measures were extremely interesting.
A very and constant big dip on all frequencies was observed on 7, 10, 14, 18, 21, 24, 28 Mhz with MFJ-259B analyzer.
I think that after these modifications, I will be quite for several years.
73 Georges VE2EK - 9Q1EK - ZS1II