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

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Do you use an antenna tuner with your receiver?  (Read 1223 times)
AB4KA
Member

Posts: 7




Ignore
« on: April 11, 2019, 08:55:33 AM »

I've got an Alinco DX-R8 (which I really, really like, but that's not the subject of this thread  Cheesy ) and I've got it hooked up to a wire that's about 50' long.  I was pleased with what I got.  But I remembered years ago I knew a guy who hooked up a little antenna tuner to a cheap receiver he had and when combined with a decent length of wire, his receiver came alive!  So just for kicks and giggles I picked up a Dentron 80-10 AT which is an antenna tuner specifically for single wire antennas.  I had one many years ago and it always did a good job for me.

Anyway, I hooked up my wire to it and connected my receiver and I'm able to hear things I couldn't hear before.  I know that opinions vary regarding the usefulness of a tuner with a receiver, but for me it seems to be a definite improvement.
Logged
WW7KE
Member

Posts: 935




Ignore
« Reply #1 on: April 11, 2019, 09:14:26 AM »

Older "boat anchor" receivers usually had an "antenna trimmer" capacitor on the front panel.  It was a small-value (5-50 pf or thereabouts) variable capacitor between the antenna terminal and the input circuits.  And even in the case of modern rigs, with a better front end and an input impedance closer to 50 ohms than the boat anchors ever were, a wire antenna still needs to be matched to its load, which in this case is the receiver input.  I would use the tuner.
Logged

He speaks fluent PSK31, in FT8...  One QSO with him earns you 5BDXCC...  His Wouff Hong has two Wouffs... Hiram Percy Maxim called HIM "The Old Man..."  He is... The Most Interesting Ham In The World!
VA3VF
Member

Posts: 2864




Ignore
« Reply #2 on: April 11, 2019, 09:15:14 AM »

Anyway, I hooked up my wire to it and connected my receiver and I'm able to hear things I couldn't hear before.  I know that opinions vary regarding the usefulness of a tuner with a receiver, but for me it seems to be a definite improvement.

You have your answer already. Grin

It does make a difference. That said, it varies based on the configuration of the ATU (T, Pi, LC, etc.).
Logged
KC6RWI
Member

Posts: 172




Ignore
« Reply #3 on: April 11, 2019, 09:41:21 AM »

You did get your answer. I have a NRD 525, a short wave receiver, the owners manual shows a simple end fed wire antenna as an example as the antenna needed. I always questioned why they showed such a basic antenna set up. It does have a hi z or low z switch.
Logged
RENTON481
Member

Posts: 275




Ignore
« Reply #4 on: April 11, 2019, 09:30:54 PM »

I built an antenna tuner that worked well in reducing images with my DX-160 (a single conversion receiver).

With most modern radios, I think YMMV.
Logged
KAPT4560
Member

Posts: 551




Ignore
« Reply #5 on: April 12, 2019, 08:52:45 AM »

 I have used a number of different active antennas that had a built-in preselector. An antenna amplifier ahead of an already well designed and tuned RF amplifier stage can introduce distortion and noise.
 It can also cut back the gain with the receiver's well-designed AGC circuit if the receiver determines that there is too much signal.
 I have shut down the amplifier section and just used the active antenna preselector section. It does cut down on images and interference from strong adjacent stations.
 As mentioned, many communications receivers already have a antenna compensator, trimmer or preselector that can be peaked to the received signal.
Logged
NO2A
Member

Posts: 1400




Ignore
« Reply #6 on: April 12, 2019, 06:00:31 PM »

When I had my hf station setup I used an MFJ 989C tuner to match it to an 80m dipole.(using ladder  line)It worked well on 80-6m. Even for broadcast band. A roller inductor tuner is really the only way to go. They're also more efficient.
Logged
HFCRUSR
Member

Posts: 350




Ignore
« Reply #7 on: April 13, 2019, 05:39:59 AM »

My SX-88 and my DX160 both have "antenna trimmers". My R8600 and R75 don't. In certain situations those trimmers can be an asset. Even in an opposite direction like if I'm DXing a small signal along side a big local signal in MW, taking the trimmer off-peak can shave IBOC or bleedover from the big signal so I can hear the desired distant signal better, especially with the DX160 which has no filter selectors.
Logged

Not a ham, but an avid hobbyist in HF world. All things, short of transmit happen in this shack.
KA3JJZ
Member

Posts: 26




Ignore
« Reply #8 on: April 13, 2019, 07:59:56 PM »

Using the term 'antenna tuner' in this situation is inaccurate. A true tuner would be placed at the feed point of the antenna, and requires a bit of RF to get it to tune. That's not an option in a listening application. What you often see advertised as an antenna tuner is really more of a transmatch.

Yes using a transmatch - or better still, a passive preselector - can help with rejecting out of band signals. This is especially true for old desktops and some SDRs too.

This article from the RadioReference wiki discusses these topics in some detail

https://wiki.radioreference.com/index.php/Improving_HF_Reception
Logged
W9IQ
Member

Posts: 3232




Ignore
« Reply #9 on: April 14, 2019, 03:55:59 AM »

Using the term 'antenna tuner' in this situation is inaccurate. A true tuner would be placed at the feed point of the antenna, and requires a bit of RF to get it to tune. That's not an option in a listening application. What you often see advertised as an antenna tuner is really more of a transmatch.

You are making a distinction without a difference.

While the term antenna tuner can be misleading, a transmatch is the same device. And neither one needs to be placed at the antenna in order to be effective. Placing it closer to the antenna tends to minimze feedline loss (with some exceptions).

A receive and transmit application both involve RF. The primary difference between them in the swapping of the role of the signal source and the load. This is often the overlooked concept when considering the function of an antenna tuner / transmatch located in the shack.

During receive, the proper adjustment of the antenna tuner / transmatch causes the input impedance of the feedline at the antenna end to closely (but not exactly due to losses) conjugately match the feedpoint impedance of the antenna. By doing so, the receiving antenna is able to transfer its maximum available power into the feedline and to the receiver. If this near match at the feedpoint did not exist, the receive antenna would re-radiate a portion of its received power thereby lessening the signal in the receiver. This is why an antenna tuner / transmatch can be beneficial while receiving.

- Glenn W9IQ
Logged

- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
N3PM
Member

Posts: 46




Ignore
« Reply #10 on: April 14, 2019, 05:31:40 PM »

I have used a tuner to eliminate shortwave "blow thru" on 40M DC receivers. Last one was a QRP-Guys tuner across(not inline) the input to a Lidia receiver. It is a tuner, but used as a trap.
Mike N3PM
Logged
N8AUC
Member

Posts: 588




Ignore
« Reply #11 on: April 30, 2019, 06:14:18 AM »

You certainly don't gain anything by placing an antenna tuner between your receiver and antenna.
An antenna tuner is a passive device, and therefore has no gain.
What it does provide, is an impedance match, and some frequency selectivity before the receiver front end.

The last part is the most important reason to use one with just a receiver.
Especially if you live in the vicinity of a strong station not in the band you're trying to listen to.

Sometimes, that out of band energy finds its way into the signal chain where the receiver AGC sees it.
You can't hear it, but the AGC sure does. As a result, the AGC decreases the gain of one or more of the
IF amplifiers in the chain. Using a transmatch to help filter out those undesired signals can help prevent
the AGC from seeing it, and prevent gain reduction. Eliminating strong out of band signals also helps to
prevent undesired mixing products which appear as spurious sign across the dial.

There are some very real benefits to using an antenna tuner (or transmatch) with just a receiver.
Logged
KD7RDZI2
Member

Posts: 425




Ignore
« Reply #12 on: April 30, 2019, 01:08:06 PM »

If I use an antenna tuner? Yes, sometimes. Do I use the AGC OFF and the RF Gain/AF volume? Yes, sometimes. Having said this, believe me, both are not mandatory for operating a receiver. They may be both useful.
If you use a very mismatched antenna, the tuner although it is a passive device will be effective in delivering most of the energy in the receiver. If you use coax as a feedline, the closer the tuner is to the antenna, the better it is. An antenna tuner generally acts like a sort of high-pass filter. If your receiver suffers from overload, the tuner may be beneficial. Some will say to use attenuators and the RF Gain or maybe simply cut the antenna Grin. But in your case, your Alinco might have already good bandpass filters built in and you may not be even need an external box.
I really like using portables, Degen, Tecsun, Sangean and alike, and the main difference with tabletops is that portables often suffer from overload when an external antenna is connected. In this case a tuner helps, but a preselector does the job even better. I have modified a MFJ-956 (which is nothin' else that a selectable inductor and air variable capacitor in series) drastically improving the 'Q' (see https://www.eham.net/reviews/review/155578) lowering the impedance of the filter adding two small transformers. Other more expensive MFJ preselectors use this trick as well. Having said I would first look for an antenna with a good Signal/Noise ratio, reasonably efficient and already reasonably well matched (SWR<2, where SWR shoud not be confused with efficiency). The tuner is more a detail, just like the RF Gain knob Grin.
« Last Edit: April 30, 2019, 01:28:41 PM by KD7RDZI2 » Logged
Pages: [1]   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!