Difference between Cushcraft A147-20T & A144-20T
Tony C Blake
I am making some final decisions on what VHF equipment to
purchase. My long range plan is to work the satellites,
but for now be content with terrestrial work. For now,
I want to run the Cushcraft A147-20T. However, while looking
over Cushcraft's AOP-1 OSCAR system, I noticed that one of
the 2m antennas is their A144-20T. This antenna appears to
be identical to the A147-20T.
Does anyone know what the difference is between these two
antennas? Will I be able to use the A147-20T for OSCAR work
in the future?
Thanks,
=======================================================================
Tony Blake DoD#9045 AT&T Global Information Solutions
tony....@ccmsmtp.stpaul.ncr.com Network Products Division
(612) 638-7259 voice 2700 Snelling Avenue North
(612) 638-8173 fax St Paul, MN 55113-1784
Disclaimer: The smelling pistakes are all my own.
=======================================================================
Daniel T Senie
>Hi Gang,
>
>I am making some final decisions on what VHF equipment to
>purchase. My long range plan is to work the satellites,
>but for now be content with terrestrial work. For now,
>I want to run the Cushcraft A147-20T. However, while looking
>over Cushcraft's AOP-1 OSCAR system, I noticed that one of
>the 2m antennas is their A144-20T. This antenna appears to
>be identical to the A147-20T.
>
>Does anyone know what the difference is between these two
>antennas? Will I be able to use the A147-20T for OSCAR work
>in the future?
>
>
>Thanks,
>
>
>=======================================================================
>
>Tony Blake DoD#9045 AT&T Global Information Solutions
Don't do it! I have an A147-20T, it is not a very good antenna. The design
is old and tired. Word has it that W1JR (formerly head designer at
cushcraft, now running his own antenna company) did an analysis of the
147 and found that at some frequencies it exhibited NO gain (zero!).
The 147 is designed to have the vertical elements tuned for 146 Mhz or so,
and the horizontals tuned for 144.2. The idea is that you get an antenna
for SSB and an antenna for FM both on the same boom. Interesting idea, but
the cushcraft implementation of the idea is BAD.
Joe W1JR said he could make a DECENT version of such an antenna if there
were interest. I am not sure if I am really interested, though.
You can use circular Oscar antennas for terrestrial work. No need to worry
about vertical or horizontal, as you'll work both. The loss is 3dB over having
just vertical or just horizontal.
And no, don't bother trying to use the A147-20T for oscar in the future. You
are likely to get a skewed pattern and a strange match on the delay lines.
Dan N1JEB
--
---------------------------------------------------------------
Daniel Senie Internet: d...@world.std.com
Daniel Senie Consulting n1...@world.std.com
508-365-5352 Compuserve: 74176,1347
Mike Stansberry
: Hi Gang,
: I am making some final decisions on what VHF equipment to
: purchase. My long range plan is to work the satellites,
: but for now be content with terrestrial work. For now,
: I want to run the Cushcraft A147-20T. However, while looking
: over Cushcraft's AOP-1 OSCAR system, I noticed that one of
: the 2m antennas is their A144-20T. This antenna appears to
: be identical to the A147-20T.
: Does anyone know what the difference is between these two
: antennas? Will I be able to use the A147-20T for OSCAR work
: in the future?
I'm saying this from memory, without looking it up. I think the
A147-20T is a verical and horizontal on one boom, cut for the
center frequency of 147 MHz. It's intended use is to have the
two antennas and be able to switch between them. The AOP-1 is
for circular polarization. I had the AOP-1 set, took them down,
bought KLM antennas and had much better luck with the satellites.
Lost a lot of money on the deal, though. My 435 MHz pre-amp would
break into oscillation when placed at the antenna with the AOP-1
set, it does not with the KLM. Could be a problem with the pre-amp,
I don't know, but it's a commercial one that matches the Icom
IC-471A radio.
Mike, K0TER
Gordon Weast
I have a 147-20T and I like it a lot.
The 147-20T is the combination of a vertical 10 elements tuned to the high
end of the band with a horizontal 10 elements tuned to the low end of the
band. You can still drive the two together with a quarter wave phasing
section to get near circular polarization but the degree of circularity
will depend on frequency since the two antennas are not identical.
The 144-20T has both horizontal and vertical parts tuned to the same
frequency in the low end of the band. Since the two antennas are
identical, the degree of circularity will only depend on the fact that the
quarter wave phasing section is only a quarter wave at one frequency.
I am not sure if you would notice the difference in not having perfect
circular polarization, you may see a few db of flutter when the satellite
tumbles.
I just use mine as two separate antennas for terrestrial work. I have also
worked through the RS sats. It is almost as good as a turnstile when the
satellite is overhead, and it works much better when the satellite is near
the horizon.
Gordon Weast
wa9wtk
gor...@westford.ccur.com
--
Wayne D Roth
: I am making some final decisions on what VHF equipment to
: purchase. My long range plan is to work the satellites,
: but for now be content with terrestrial work. For now,
: I want to run the Cushcraft A147-20T. However, while looking
: over Cushcraft's AOP-1 OSCAR system, I noticed that one of
: the 2m antennas is their A144-20T. This antenna appears to
: be identical to the A147-20T.
: Does anyone know what the difference is between these two
: antennas? Will I be able to use the A147-20T for OSCAR work
: in the future?
I have the 147-20T, and if you use it for H on one feed, and V on the
other it works pretty well. I've run them simultaneously (while gritting my
teeth) and rx while tx is possible, but you get desense of course. I was
initially afraid that I might blow out the front end of the rx, but the
90 degree orientation gives you enough attenuation.
As far as satellite work, I agree with the fellow who lost a lot of money
going to the klm's. I've never had the 144-20T, but have heard them on
ao-13 with my KLM's. People make fun of you if you have the cushcrafts,
although just in jest of course. I suggest that you spend a few bucks on
the aluminum, and get KLM's if you want to work satellites.
Regarding circular polarization, the difference in listening to those who
use linear on AO-13 to circular is significant. The folks who use L have
an annoying scalloping from the satellite's rotation.
For the LEO birds, the cushcraft would be more than enough, but you'll
get tired of them for analog work. Digital work on them is a lot of fun, but
you'll want to be automated to do that.
Good luck,
Wayne Roth
WA2N / 5.
phil moore
>In article <tony.blake....@stpaul.ncr.com>,
>Tony C Blake <tony....@stpaul.ncr.com> wrote:
>>Hi Gang,
>>
>>I am making some final decisions on what VHF equipment to
>>purchase. My long range plan is to work the satellites,
>>but for now be content with terrestrial work. For now,
>>I want to run the Cushcraft A147-20T. However, while looking
>>over Cushcraft's AOP-1 OSCAR system, I noticed that one of
>>the 2m antennas is their A144-20T. This antenna appears to
>>be identical to the A147-20T.
>>
I've seen comparisons of KLM and Cushcraft antennas, but what about
the Hy-Gain 260 and 7030 SAT system or the M2 antennas?
----
Phil Moore, Geological Sciences, USC, Columbia,SC, 29208
StratMod Group/Signals Project (803)777-5202, FAX 777-6610
Email:ph...@epoch.geol.scarolina.edu Packet:ad...@kc4gym.sc.usa.na
--
Phil Moore, Geological Sciences, USC, Columbia,SC, 29208
StratMod Group/Signals Project GEOL<->CSCI (803)777-5202, FAX 777-6610
Email:ph...@epoch.geol.scarolina.edu Packet:ad...@kc4gym.sc.usa.noam(.earth.sol)