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G6AOS > YAESU 05.12.04 10:23l 124 Lines 3921 Bytes #999 (0) @ WW
BID : 181421G6AOS
Read: GUEST DG8YHH DK7JY VE7HFY
Subj: Yaesu, Built to FAIL
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<GB7FCR
Sent: 041205/0807Z @:GB7FCR.#16.GBR.EU #:24871 [Blackpool] FBB-7.03a $:181421G6
From: G6AOS@GB7FCR.#16.GBR.EU
To : YAESU@WW
Greetings Campers..
Well after differnt comments about the 290
G0FTD wrote:-
> Yaesu - no thanks
Well Heres my tuppence worth if anyone is interested:-
I've a old yaesu 901 HF rig,
(If you are a 101-2 901-2 Owner this IS VERY relevent to you)
(Do you Value your rig and want to keep it running as long as possible)
This is likely relevent to many other Valve output rigs also.
ok this is "my personal" thoughts, (you can draw your own conclusions)
~~~~~~~~~~~
I had concluded after hours of work, That the 901 was built to fail and
when it did it would fail in good style and fashion many times over.
Please consider:-
1/ how FYEW (many) fuses protect your rig.
2/ Having been inside the lower part of the Pa compartment in the 901
How tightly stuff is shoehorned in.
DID YOU KNOW:-
The sleeving on legs on some components in the pa compartment which chriss
cross each other is NOT HEAT PROOF.
Add 20 years of heat dirt and dust ect
It can stick to the sleeve and cause discoleration.
ok NOW consider If you have one of the above mentioned rigs, thats not
used regularly, and its switched on and the heaters are switched on and
one leaves the rig to its self to warm up before use.
How do you know if its about to go up in smoke?.
>>>>>>>> Well you dont! <<<<<<<<<
Ok now consider this:-
The Vast majority of rigs only have a single meter that when the rig is on
receive theres absolutely no means of seeing what the transmitter valve
supplys and stages is doing.
The Ic of the Pa valves IS NOT monitored till your transmitting, so what
if somthings going wrong?.
Well What happened to this 901 was as far as I can tell, (It came to me as
scrap, without a transforemer and blown up)
The Pa for what ever reason started to conduct in the RX mode,
IF the Bias is wrongly set (too high) or an intermittent and the bias
voltage wanders perhaps a high resistance joint a bad connection on the
plug of the bias pcb, whatever.........
The valves switch on,,,, but its NOT monitored.
hotter and hotter, (stinking hot in perhaps 10 mins or less!.)
The heat in the lower part of the pa compartment gets the PLASTIC SLEEVING
mentioned before hot and it melts sufficently to allow the criss cross of
wires to the fixed capictors to short. Result! Bang!....
to the cost of the rig and your wallit.
The HV is shorted to chassis, the HV supply PCb is destroyed, the mains
transformer melts, blowing the fuse.
The Pa valves well probably all but destroyed in the process.
If you are a serious user and would NOt like this to happen to you, you
may like to consider the options.. or you just wonder why your old rig
blew last week / year.
1/ increase protection (more fuses - of a suitable type and rateing)
Fitted where it matters.
2/ monitor the Ic and the high voltage parts of the set by means of the
accessory socket even while on receive.
3/ Never EVER, leave the rig un-attended with heaters switched on!.
Oh and please note I still like the Receiver proformance of the 901 as
with its shift and reject controles, it picks out of a well overcrouded
40m band
in a contest that station in the back of the box, that is completely
un-workable on my kenwood (ts680s).
But the EARLY 901's never had the 9 megs trap fitted and the rtty station
2kc's off the I.F frequency of the 901 is a darn nusance blasting the rig
to bits.
ok campers well thats it, and oh remember with electronics,
"What can happen will and does with amazing regularity"!.
Bang!......................
anyone else got any interesting coments on yaesu rigs they may consider
putting on here?.
Best wishes to all Steve (G6AOS@GB7FCR.#16.GBR.EU)
Steve's Tagline for today...
I dont make spelling mistakes - my keyboard does!.
73 - Steve, G6AOS @ GB7FCR
Message timed: 07:06 on 2004-Dec-05
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