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G4KKI
william stevenson
Class A Class
G4KKI Ham Since 1980
United Kingdom

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My Ham Radio Interests
QRP-CW
homemade equipment,
backpacking and sota

Equipment
FT817ND,
HB1A
SW40=
MFJ rigs
FT840
SST20

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HW7

From G4KKI

1/15/2011 3:14:57 PM (2 comments) Add a commentAdd Comment


After managing to repair a HW7 for a friend G0GGK, i tried it out on 40 and worked a few stations in the HA test today.
F6CEL and HA8RM.I don't know what the previous owner had done to it before he sold it to Dave but it was totally dead!
I found that a zenor was short circuit and the RF choke that
was in circuit with it must have glowed white hot because the pcb under it was black with carbon. A couple of resistors had also burnt. After replacing the zenor and resistors it started to receive ok but on tx it would take off and was just not useable. I tried different things to stabalise it with no success. In the end i made a homemade choke and tacked it to the back of the board and it gave a stable output on 40/20, also stable on 15 but very low output.
I think the burnt pcb, which is really burnt! is the problem. It measures 200k across the burnt section. If it was mine i think i would remove the final output stage and add some switched low pass filters and do away with the variable cap.


Read the 2 comments after the break below.

Comments

by KA6KBC 1/16/2011 10:26:20 PM

I bought an HW 7 back in the early 80's. Made lots of contacts with it on 40 Meters. The higher bands worked ok, but it was best on 40 Meters. The Rx is a direct-conversion receiver, which can be touchy but they work. My guess is the Transistor finals are flat and the input power was connected in reverse. I remember seeing an article recommending to add a diode in the Positive input line.

Good work getting it up and running - This radio is lots of fun.

73's - Bill - KA6KBC

by G4KKI 1/16/2011 11:10:46 PM

Thanks Bill, yes the HW7 is a fun rig, i had one back in the early 80's myself and i worked all over the place. Best dx with it for me was ZL/VK on 20mtrs.
I'll check out the finals.
73's - Bill-g4kki


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