KLM Amplifier UHF Model PA 15-110CL

[scotttish]

Hello all! I bought a KLM UHF 110 watt amplifier that I need to learn how to use with my 45 watt radio. On the back, it has two connectors. One marked, Xcver, and one ANT. There is no user manual. Which connector from the external antenna goes into the amp, and which one goes into the radio? I have a great roof antenna, but the amplifier may give my radio a better push. So far, no changes in reception. I know that these may be dumb questions, but the dumb question is one that is never asked,,Thanks!

 

[prcguy]

First off the amp is rated for a maximum of 15 watts input, so your 45w radio needs to be reduced to 15w max, otherwise you will probably blow it up. Then you will have a little over 3dB gain going from a 45w radio to 110w out of the amp, if the amp actually puts out that much. Hardly worth the effort in my opinion because nobody will see much difference in the 3dB change in power.

The amp is also intended for the 420 to 450MHz amateur band. Where do you want to use it? If its for GMRS or other UHF commercial freq the output will probably be further degraded.
prcguy

 

[toastycookies]

First off the amp is rated for a maximum of 15 watts input, so your 45w radio needs to be reduced to 15w max, otherwise you will probably blow it up. Then you will have a little over 3dB gain going from a 45w radio to 110w out of the amp, if the amp actually puts out that much. Hardly worth the effort in my opinion because nobody will see much difference in the 3dB change in power.

The amp is also intended for the 420 to 450MHz amateur band. Where do you want to use it? If its for GMRS or other UHF commercial freq the output will probably be further degraded.
prcguy

3db is HUGE!

 

[prcguy]

Its the same as going from 1w to 2w on a handheld, it usually goes unnoticed. If the OP had a 10 or 15w radio then he will see a huge increase with the amp in line.
prcguy

3db is HUGE!

 

[eaf1956]

Hello all! I bought a KLM UHF 110 watt amplifier that I need to learn how to use with my 45 watt radio. On the back, it has two connectors. One marked, Xcver, and one ANT. There is no user manual. Which connector from the external antenna goes into the amp, and which one goes into the radio? I have a great roof antenna, but the amplifier may give my radio a better push. So far, no changes in reception. I know that these may be dumb questions, but the dumb question is one that is never asked,,Thanks!

The antenna connects to the ANT connector The radio output connects to the Xcver or transceiver connector. And as they said reduce your transceiver output to the rated input of the Amp.

 

[jwt873]

Its the same as going from 1w to 2w on a handheld, it usually goes unnoticed.
prcguy

Yes... It's also the same as going from a 1000 Watt amplifier to a 2000 Watt amp. You still only gain 3 dB.

A 3dB increase in power will give you one theoretical S unit on the receiving station.

 

[prcguy]

An "S" unit is a 6dB change and a 3dB change is one half of an S unit change.
prcguy

Yes... It's also the same as going from a 1000 Watt amplifier to a 2000 Watt amp. You still only gain 3 dB.

A 3dB increase in power will give you one theoretical S unit on the receiving station.

 

[TITANIO]

KLM 15-110CL

Nice amp. I also have one and get about 60w out with only my HT on High as a driver.

- I think it's a great idea to run the amp behind the mobile so the amp does the work letting the mobile rig run cooler, always a good idea to run as cool as possible.

- I'd run about 10w in and you should get between 90w-100w output. Many older mobile rigs have a VR for adjusting the wattage out on the different power level settings, and many newer rigs offer that option in their software.

- Oh, and 3dB is close to a full S-unit on many - most meters. I usually see around 3.5dB - 4.5dB per S-unit.

- That old 6dB/S-unit myth comes from the old Collins gear which held fairly close to 6dB/S-unit, though today you see widely varying non-linear AGC circuits sometimes even showing a full S-unit for only 1dB - 2dB increase in power.

 

[jwt873]

As a point on interest, when discussing dB, you have to state whether you're dealing with voltage or power.

The formula for calculating power dB is .. 10 (log(P1/P2)
The formula for calculating voltage dB is .. 20 (log(V1/V2)

So, doubling power results in a 3 dB gain, and doubling voltage results in a 6dB gain.

When you're dealing with transmitters, you're dealing with power to the antenna. Receivers deal with voltage from the antenna.

So, a power increase of 3dB from the transmitting antenna will result in a 6dB voltage increase at the receiving antenna. (3dB is a doubling of power, 6dB is a doubling of voltage).

As TITANO points out, S meter measurement gets kind of dodgy. Different manufacturers did use their own system. Plus, S meters are notoriously imprecise.

But, the popular 'industry standard' is to use 50 microVolts on the antenna = 0dB. This is measured as S9.. Cut that in half (25 mV) and you have a 6 dB decrease which should be S8. Cut that in half again down to 12.5 microVolts and you have S7 and so on. These are theoretical values.

As I indicated in my previous post, doubling the power out (3dB) will provide one 'theoretical' S unit at the receiver (6dB).

 

[prcguy]

There is and always has been only one spec for an S unit, and its 6dB per increment. The problem is most manufactures don't have enough consistency from radio to radio, or from the prototype radios to production, or aren't willing to spend the labor to custom align each radio. Some companies like TenTec do however calibrate each and every S meter in some models and they are very accurate.

Another thing that happened about 40yrs ago is the original S9 standard (Collins?) was 100uv for S9 and the Japanese mfrs adopted 50uv for S9, which has been the standard since.
prcguy

 

[majoco]

Nothing to do with Collins or any manufacturer. The IARU proposed the scale for "S" meters many moons ago. S0 to S9 - 6dB per step and S9 was to be 100uV EMF at the antenna terminals or 50uV in 50ohms. Whether the manufacturers could comply or not was entirely up to them. Nowadays with better receiver design it shouldn't be a problem but older receivers had different gain at different frequencies.