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Friday, November 29, 2013

ZJ Beverages and how it works - part II.


as I promised there I am posting the open discussion about the ZJ Beverages as I found it on the reflector.

TopBand: ZJ Beverage Box Comments and Update de W0AH
from [W0AH@aol.com] [Permanent Link][Original]
To: <topband@contesting.com>
Subject: TopBand: ZJ Beverage Box Comments and Update de W0AH
From: W0AH@aol.com (W0AH@aol.com)
Date: Wed, 5 Nov 1997 16:47:09 -0500 (EST)

On Oct. 22 I posted to the list that I was not happy about the performance of my NE beverage and also that my ZJ Beverage Box was not working and that I was going to try and fix it.

Several wrote and asked me to send them any information I received since
they also need ed to fix the ZJ beverage box. Therefore, this post.
First, I want to say that my ZJ beverage box worked fine when I first
installed it a couple of years ago. It brought my beverage signal up 2 or 3S-units as I recall. I had no intermod (I have no local commercial
stations). Using a coaxial hand switch between the transmitting antenna and the beverage (my transceiver had no separate receive antenna), I forgot to switch the antennas and ran power into the ZJ box.

I wrote ZJ, which a month later sent me a replacement device, gratis.
Now, over a year later, wanting too repair the ZJ box, I can not find the device he sent me. Thus my inquiry to the list recently.

My ZJ Box did not come with a schematic which is my main complaint.
Looking at the device, I thought it was a gasfet, but I have been informed by KM1H, W8JI, and K0CS that it is a MMIC. MMIC stands for Monolithic Microwave Integrated Circuit Amplifier. I have built several of the well regarded Down East Microwave kits (for 902, 1296, and 2304 MHz) which use MMICs. Both KM1H and W8JI wrote that the MMIC was a poor choice for a 1.8 MHz preamp. I agree that it is an odd choice, but my Avantek Semiconductor Data Book shows that the power gain and other MMIC specs are flat from about 0.1 to about 1 or 2 GHz, depending on the specific device. Also, the Avantek power gain versus frequency chart shows them being flat to DC! Therefore, the device should be suitable for 1.8 Mhz.

KM1H siad there had been a discussion of the ZJ Beverage Box which can
be found in the archives. So more information is available there. He also said that the ZJ Boxes had been shipped with "at least 4 different" MMICS including the MAR1, MAR3, and others. He stated that some of those devices needed different biasing. He also stated the ZJ Box was subject to overload and IMD. Carl said the "ultraminature 9:1 balun is just as bad." W8JI suggested replacing the MMIC with "a regular CATV transistor."

W4MPY wrote that his ZJ beverage box filled up with water and that he
has tried unsuccessfully to get help from ZJ.

Both W8JI and KM1H stated that a good beverage will not generally need
a preamplifier.

K0CS kindly sent me a MAR-3 device which had been supplied by ZJ as a
replacement device.

Looking at the various Avantek MMIC specs (I can not find my cross
reference to compare the Avantek MSA MMICs to the MAR MMICS) I see several MMICs with very similar specs (in some cases just different plastic packages-ie. cases). Almost all of them require 4.5 to 5.5 volts DC. I suspect the several different MMICs supplied in the ZJ boxes have identical specs at 1.8 MHz and that biasing is not an issue. For those who need to replace the MMIC, a MAR-1, MAR-3 or equivalent should work fine. MMICs are listed in several of my electronic catalogs for about a dollar each.

I hope the above is useful information and that some of you get your ZJ
beverage boxes back up and running. Unfortuately, mine still is not working after I replaced the MMIC. I suspect that the ultraminature balun, as KM1H described it, needs replacement. Not sure I want to proceed until I get a schematic. Does anyonwe have one? See also my next post on beverage transformers. Doug W0AH

TopBand: ZJ Beverage Box MAR3 MMIC Replacement?
from [km1h @ juno.com] [Permanent Link][Original]
To: <topband@contesting.com>
Subject: TopBand: ZJ Beverage Box MAR3 MMIC Replacement?
From: km1h@juno.com (km1h @ juno.com)
Date: Thu, 23 Oct 1997 18:58:41 EDT

On Thu, 23 Oct 1997 15:44:36 EDT W0AH <W0AH@aol.com> writes:
>Thanks K0CS for the info that the ZJ Beverage Box uses a MAR3 MMIC,
>which are quite inexpensive .

Wrong info Doug. Your ZJ "thing" has a MAR-1 in it according to ur
number. Owners have found at least 4 different MAR MMIC's so far. NOT interchangeable without changing bias resistor either.

As discussed here at length a month or so ago, the choice of device PLUS
the matching xfmr in the ZJ box makes it an all around poor choice for Beverages. Nice and cute toy but no good for real world use. Suggest you check the Archives for comments by users, W8JI, myself, etc.

73 Carl KM1H

I thought I had a MAR3 around here, but can't find it.
Can any of the following Avantek be substituted for the MAR3?
Avantek 0185, 0285, 0485, 0685?????
I'll post a message as to how this all turns out as others have contacted me concerning their non-working ZJ Beverage boxes.
I have the above. If no answer, I'll try to call WB5LUA, Mr. MMIC!
Doug W0AH

Well any other experiences with this system even negative are welcomed over there.

73 - Petr, OK1RP

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