[Hammarlund] Wanted: HQ-100A improvements

[Glen Zook]

According to the manual the HQ-100 is supposed to
match 50 to 600 ohms.  Now, I have found that many of
the 3-terminal antenna connection receivers are
improved greatly by the use of a TV type balun.  Now,
some people have found that certain baluns do not work
down into the HF amateur bands.  However, any balun
that is made for use on a cable TV system is supposed
to make it down to at least 5 MHz.  In fact, every
cable TV balun that I have ever used make it down into
the AM broadcast band without any problems.

It is very simple to try a TV balun and see if it
improves the sensitivity of the receiver.  Just make
sure that you remove the jumper between the antenna
terminal next to the ground terminal when you use a
balun.  When using coaxial cable you need to jumper
the 2nd antenna connection to ground and to connect
the shield of the coaxial cable to those terminals. 
The center conductor, of course, goes to the first
antenna terminal.

There are adpators made to convert the female type "F"
TV connector to a female BNC connector for use with 50
ohm coaxial cable.  Of course you can make an adpater
using a type "F" male and an SO-239 female UHF
connector with a short piece of 50 ohm coax between
the two connectors.

Now, the "stock" HQ-100 uses the Q-Multiplier put into
regeneration for the BFO.  This is marginal at best! 
There was an accessory BFO available for the HQ-100
which is much better.  Of course you aren't probably
going to know if your HQ-100A has the accessory BFO or
not.  Unfortunately, most HQ-100 series receivers do
not have the accessory BFO.

On many receivers the use of a TV balun gets the
sensitivity down well below 1 microvolt.

Glen, K9STH


--- Edward B Richards <zuu6k@juno.com> wrote:

Also, I see the antenna impedance is 100 ohms. What is
the best way to match this to 50 ohms?

=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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