[AMRadio] BC-610 terminating impedance

rbethman at comcast.net rbethman at comcast.net
Sun Oct 30 12:03:24 EST 2005

The biggest difference with the link in the BC-610s, is that the link is on a pivot joint that is fixed on the center line of the loading coil.  You can rotate the link from vertical and in line with the turns, OR you can place it perpendicular to the turns AND anywhere in between.

You CANNOT take the link outside the coil proper.

This vastly limits the variability of load impedances.

I do not know when the fixed link coils ceased to be issued.  However, the 1952 manual shows the issued coils to ALL be the rotating link variety.

The "animals" or as most refer to them, "Beasts", are indeed a horse of a different color.

The A, B, C, & D variants have different manuals - AND - may well have different characteristics.  The E, F, G, H, I, and T-213 manual was published in October 1952.  

My I variant is indeed a Hallicrafters manufactured one.  So noted by data plate and Hallicrafters logo on the tuning units.

I believe my T-213 is a B&W manufactured one.

Both came with an SO-239 output connector.  The I model also has the porcelain feedthroughs.  When looking inside, I find the lines to the feedthroughs ALSO go with one to ground and the other to the center conductor of the SO-239.

As to polarization of antennas, there is no question that long haul propogation DOES constantly change.

My point was the use of the Mil issue 25ft vertical whip.  As it has a very short length, its capture ability and transmission ability would be severely degraded in comparison with a manufactured Ham vertical.  That was my basis for saying that I had no use for a "vertical" to be installed off the back of the BC-939.

I have consistently used dipoles and inverted vees for my station.  I have had no issues, and have been very happy with the results qith QSOs up and down the entire East Coast, and well into the MidWest.

Antennas ARE the only black art left.  I have always found them to interesting.

As to my reference to the VSWR/SWR, I was explaining the reading into a 50 ohm dummy load that is internal to the ME-165G - NOT into a feedline.  I feel very comfortable that the reading I referred to was indeed indicating that the transmitter WAS indicating a 50 ohm unbalanced output.

Sorry - but I am NOT putting my antenna bridge looking back into the transmitter.  I like my bridge, and am NOT looking to allow ALL of its "smoke" to depart.

The manual for these two radios ALSO states to connect the transmitter to the BC-939 tuner by COAXIAL cable.

Bob - N0DGN

> 	I may have missed something here amongst all the messages and I
> really am not too familiar with the BC610 but I thought it had variable
> loading with an adjustable 3-4 turn link.  If so, it should be able to
> load into a fairly wide range of loads.  On my variable link rig I can
> go down to about 10 ohms load by pulling the link out to maintain the
> proper plate current, but with the link in all the way the proper
> loading (indicated by plate current)is reached when the load is about
> 100 ohms.  Of course if the load is 10 ohms and the link pulled out for
> proper plate current I need to be very careful not to pour the coals on
> with the plate voltage or the link will over heat.  I have been able to
> load to proper plate current with a 300 ohm load but I had to parallel
> tune my link instead of series tune.  

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