[AMRadio] BC-610 down=up and burnt't finals


John E. Coleman (ARS WA5BXO) wa5bxo2005 at pctechref.com
Wed Oct 26 17:09:30 EDT 2005


Not disputing any of what you said Bob.  
I just remembered a funny situation where Otis, K5SWK, had some one else at
his rig controls. The rig was and is single 833 modulated by a pair and this
story was of many years ago.  The person at the controls is now a silent key
but I still won't mention his name.   The story goes that Otis was down the
street buying cigarettes, beer or something, and this person was visiting
from out of town.  Not realizing the rig had had a arc over on the tuning
capacitor, that is never experiencing anything of that size before, the
operator continued to talk while the big pole pegs melted the plate of the
833 in the final.  The 833 had a hole burnt through the plate the size of a
half dollar after the circuit breaker on the house when pop.  The funny part
of this story is that that tube was a very good tube and continued to work
perfectly with out even a drop in grid current at full output.  I ask Otis
if the tube showed any color and he said that he could not see the other
side but that on the side facing him there was no place for the tube to show
color.  He did change the tube later because he said that it was just too
weird to look at the grid and heater through the hole and not see the normal
little red glow that was supposed to be there on the plate.

John, WA5BXO   

-----Original Message-----
From: amradio-bounces at mailman.qth.net
[mailto:amradio-bounces at mailman.qth.net] On Behalf Of rbethman at comcast.net
Sent: Wednesday, October 26, 2005 3:58 PM
To: Discussion of AM Radio; Discussion of AM Radio
Subject: Re: [AMRadio] BC-610 down=up

As to folks ideas as to what constitutes a "long" wire, THE manual AND the
tuning cards for the BC-610 are VERY specific about the 44 ft for 80, 40, &
20 mtr bands, AND is very specific about the 77ft for 160 mtrs

The BC-939 is used EITHER for a 25ft  vertical whip, or the above mentioned
wire lengths.  When using the wire lengths as stated in the manual and
tuning cards, you MUST place the switch on the fron to the "Long Wire"
position.

Seems interesting to me that this old radio was used in WWII, Korea, AND
Viet Nam with all of this working JUST FINE.

If you don't like the BC-939 and its settings, you just erect dipoles for
each band desired.  Just DON'T use a trap dipole.  You WIL NOT get a proper
tune and load!  
Of course if you want to stock up on a BUNCH of 250THs, you CAN have it you
way.  I've got one that someone sent me when they insisted on THEIR way.
There is very definitive light all the way through opposing sides in the
middle of the plate.

YMMV
Bob - N0DGN
My 250THs are just fine!


> On 10/26/05, W7QHO at aol.com <W7QHO at aol.com> wrote:
> >
> > In a message dated 10/25/05 8:18:51 PM, chejmw at acsu.buffalo.edu writes:
> >
> > > Actually,
> > > The BC-939 (*) handles an end fed long wire, the recommended length
for
> > > 2 - 18 Mhz is 44 feet. That number changes to 77 feet for 160 meters
and
> > > works quite well.
> > >
> > Actually,   a 44 (or 77) ft antenna is not a very "long" wire even at 18
MHz.
> >   The term is usually used to describe wires measured in wavelengths as
> > opposed to feet and inches, see various ARRL and other antenna books.
> 
> Apparently Hallicrafters and/or the military considered it long enough
> to qualify since the 3 position switch on front of the tuner has 'long
> wire' specifically listed in the center position. My guess is that
> they considered any random length beyond what would qualify as a
> 'whip' to be a long wire, perhaps in the spirit of the original term.
> 
> The odd thing about my A model is that the lower vacuum cap has been
> removed and replaced with an air capacitor, screwed to the base with
> heavy wire soldered to each of the two clips. It resembles a moderate
> sized air variable but with only 5-6 stationary plates. Looks to
> either be factory installed or later upgraded. Haven't had time yet to
> investigate the value or rating.
> 
> Very well-built piece of equipment, even if it has limited utility.
> 
> ~ Todd/'Boomer'  KA1KAQ
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