Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Looking for Portable (Not Mobile) XCVR  (Read 4499 times)
KF7DS
Member

Posts: 190




Ignore
« on: April 24, 2012, 08:53:48 AM »

All:

My base station has an IC 7600 (want something slightly smaller and lighter for portable use) and I want to purchase a second xcvr that will work well on vacations, at the park, etc..(not mobile i.e. no car installation). I plan on powering the xcvr with a 12v 14ah battery and want a xcvr that will work well with that power source.

 I have been considering an IC 7000; however, I have read posts that the TX becomes distorted easily when power drops below 13v, so it does not seem to be a good candidate for portable power.

I primarily operate CW, but do do some SSB, especially during contests. Price range is up to $3,500.

Suggestions welcome.

Don KF7DS

Logged
WB2WIK
Member

Posts: 20595




Ignore
« Reply #1 on: April 24, 2012, 09:08:00 AM »

Elecraft KX-3: http://elecraft.com/KX3/kx3.htm

Small, light, portable, very low current drain, and state-of-the-art.

Its receiver will literally outperform your IC-7600, and perhaps notably.

Beware there is a waiting list for these, as they just started shipping them.  You may have to wait a couple of months; it's probably worth it.
Logged
WB6BYU
Member

Posts: 13243




Ignore
« Reply #2 on: April 24, 2012, 09:21:10 AM »

I use an Elecraft K2, which replaces a Ten-Tec Argonaut for the same purpose.
Both run well off of a gel cell battery.
Logged
WA3SKN
Member

Posts: 5480




Ignore
« Reply #3 on: April 24, 2012, 11:34:07 AM »

With your budget, I would be looking at the Elecraft and Ten Tec lines.  Both will handle battery operations better than most of the others.  And the new KX3 does look very promising for your planned operations!
73s.

-Mike.
Logged
KF7DS
Member

Posts: 190




Ignore
« Reply #4 on: April 24, 2012, 12:32:21 PM »

Yes, the KX3 does look nice and I anxiusly await user reviews. I would only purchase it with the Amp option to 100w when it becomes available, otherwise not interested.

Don KF7DS
Logged
KG4RUL
Member

Posts: 2722


WWW

Ignore
« Reply #5 on: April 24, 2012, 01:14:05 PM »

"I plan on powering the xcvr with a 12v 14ah battery"

And you are waiting for the 100W version?  Sounds a little contradictory to me.
Logged
WB6BYU
Member

Posts: 13243




Ignore
« Reply #6 on: April 24, 2012, 02:37:08 PM »

I agree.

I usually figure the maximum current from a gel cell battery is 1/4 of the capacity.
Higher currents lead to more internal voltage drops.  You can get low voltage
on the audio peaks and other problems.  Most cells are rated for a 20 hour discharge
rate, and you'll get considerably shorter operating time at a higher current draw. 

Based on that, you probably shouldn't plan on drawing more than about 4A from
a 14Ah battery.  That might get you to about 20 watts output with reasonable
efficiency.  The full 20+ amps required for a 100W radio is not a good choice
for such a battery.  Yes, you might make a few contacts, but it certainly wouldn't
"work well with that power source".

I occasionally run my 100W rig from a 33Ah battery - even that is pushing the
guideline, but I usually run around 50 watts max, and don't transmit much.
Logged
WB2WIK
Member

Posts: 20595




Ignore
« Reply #7 on: April 24, 2012, 03:55:50 PM »

All:

My base station has an IC 7600 (want something slightly smaller and lighter for portable use) and I want to purchase a second xcvr that will work well on vacations, at the park, etc..(not mobile i.e. no car installation). I plan on powering the xcvr with a 12v 14ah battery and want a xcvr that will work well with that power source.

I think there's a disconnect; a 14AH battery won't run a 100W output transceiver for more than perhaps a very short period of time.  A 100W transceiver draws at least 200W from its source and the WH rating for a 14AH wet cell is "maybe" 168 WHr.  That might indicate 30 minutes of transmitting time at full power.

I'd run less power or use a bigger battery. Wink

 
Logged
KF7DS
Member

Posts: 190




Ignore
« Reply #8 on: April 24, 2012, 10:56:52 PM »

Points well taken.

Don KF7DS
Logged
HB9PJT
Member

Posts: 268


WWW

Ignore
« Reply #9 on: April 24, 2012, 11:54:51 PM »

A 100 watt TRX draws 5 to 6 amps avarage when transmitting SSB or CW. And maybe 1 or 2 amps for receive. So a 12v 14ah battery would work for 4 h work (2-3 h RX and 1-2 h TX). But when transmitting the voltage of such a lead battery can drop and can cause problems with transmitting. Other battery types of the same size like NiMh, NiCd. or LiPo will drop less when transmitting.

73, Peter - HB9PJT
Logged
N3JBH
Member

Posts: 2358




Ignore
« Reply #10 on: April 25, 2012, 06:03:42 AM »

I wonder if a TenTec Jupiter or Omni7 with a built in tuner be good for this? The Jupiter is pretty light weight and the both have good tuner's in them. And while there not the smallest rig's out there they are easy to work and sure don't weigh much.
Logged
W8JX
Member

Posts: 5777




Ignore
« Reply #11 on: April 25, 2012, 06:24:30 AM »

A 100 watt TRX draws 5 to 6 amps avarage when transmitting SSB or CW. And maybe 1 or 2 amps for receive. So a 12v 14ah battery would work for 4 h work (2-3 h RX and 1-2 h TX). But when transmitting the voltage of such a lead battery can drop and can cause problems with transmitting. Other battery types of the same size like NiMh, NiCd. or LiPo will drop less when transmitting.

73, Peter - HB9PJT


Most receivers draw about 2 amps or more and average transmitter power drain for 100 watt SSB is going to be a lot more than 5 or 6 amps. This logic only allows 3 to 4 amps above nominal receiver draw to power transmitter. More realistically you are looking at average or at least 8 to 10 amps. And, the problem is that the peaks will cause voltage drop and efficiency loss due to internal battery resistance. A trick I learned long ago with high power portable is to use a 100,000 ufd cap in parallel with battery near rig and it truly reduces peaks loads on battery and provides a steadier drain on battery at a lower level which improves battery efficiency.  The CAP feeds rigs peak demands and recharges during modulation lows. It extends battery life because it reduces peak draws on battery and loss of efficiency during these peaks. It also provides a much more stable voltage to rig while transmitting.
« Last Edit: April 25, 2012, 06:30:15 AM by W8JX » Logged

--------------------------------------
All posted wireless using Win 8.1 RT, a Android tablet using 4G/LTE/WiFi or Sprint Note 3.
AA4PB
Member

Posts: 12840




Ignore
« Reply #12 on: April 25, 2012, 06:49:46 AM »

You've also got to remember that most battery AH capacity is specified for taking the battery down to about 10VDC. If the radio won't function below say 11.5VDC then you are going to get much less than the rated AH capacity from the battery.

Also, a 2A constant receive current will generally use much more of the battery capacity than the higher but shorter time period transmit current. When looking at radios for portable use, finding one with a lower receive current (such as Elecraft models) can make a big difference in battery capacity requirements.
Logged
KF7DS
Member

Posts: 190




Ignore
« Reply #13 on: April 25, 2012, 10:45:20 AM »

Thanks for the thoughts on batteries/portable power. This has been enlightening for sure. But, getting back on topic, what xcvr works well on portable power?

One vote for the KX3, which is a strong contender and designed for portable use, and someone else suggested a Ten Tec Jupiter, which is an interesting choice.

Thanks
Don KF7DS
Logged
G4AON
Member

Posts: 529




Ignore
« Reply #14 on: April 25, 2012, 11:53:07 AM »

As others have said, if you want 100W and a small gel cell, the two are not compatible... Regardless of the apparent peak current of the gel cell.

I run a Kenwood TS480SAT (100W) "car portable" where I use a leisure battery to power the transceiver and also to power a laptop for logging and DX Cluster purposes. I can operate for around 6 or 7 hours without the battery Voltage sagging too low. The battery is a 110 Ah job which is now 5 years old and is being replaced this spring with another similar one. After 6 to 7 hours use the battery is well down.

Another consideration is the ability of the battery to survive deep discharge. The smaller the capacity, the deeper will be the discharge and the shorter the life.

My K3 is perhaps typical of the efficiency (or lack of it) when running less than full power. The current from it is as follows on 14 MHz:

100W 21A
50W 16A
25W 12A
10W 4A (PA bypassed below 12W)
RX 1A

The current on receive is probably half that of many other transceivers. As shown above, running half power doesn't equal half current. I don't have a meter to hand to check my 480, but the results will be similar. The K3 has built in metering so it easy to check...

You can either run a lower power radio with a small gel cell, or run a 100W radio from a heavy battery.

In answer to your question on radios running from lower than "shack" Voltage, the K3 will deliver 85 Watts from an 11 Volt supply. The 480 gives around 70 Watts.

73 Dave

« Last Edit: April 25, 2012, 11:56:26 AM by G4AON » Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!