# [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)

Fabio Azzarello iw8qku at amsat.org
Wed Apr 21 04:46:41 PDT 2010

```Hello,
thanks for the reply, but now I have another question.
I'm not good enough with those numbers!

If the calculated ERP is about 243 MW... which derives from changing from
dBi to dBd (60dBi - 2.14),
the part I don't understand is:

"*Since the given ERP is 243,902,443 Million Watts (see below)
and since 60 dB is equivalent to 1000000 (one Million) time in
power it comes out that the power reaching the feed of the dish is:
243902443 / 1000000 = 243 watt

The rest of the power 400-243 = 157 watt is lost in the feed line.*"

How do they have feeder losses?

73s
Fabio
iw8qku

On Wed, Apr 21, 2010 at 8:45 AM, Mateusz <sq7dqx at poczta.onet.pl> wrote:

>
> 60dBi is abt 57dB
> It means 10exp5,7
> ERP was 400x10exp5,7 W
>
> ----- Original Message ----- From: "Fabio A" <iw8qku at amsat.org>
> To: <AMSAT-BB at amsat.org>
> Sent: Tuesday, April 20, 2010 8:26 PM
> Subject: [amsat-bb] Re: Arecibo on 432 MHz Moon Bounce (some calculations)
>
>
>  Hello all,
>> just a curiosity, how did you found that the ERP is "... 243,902,443
>> Million
>> Watts".
>>
>> Thanks
>>
>> 73s
>> Fabio
>> iw8qku
>>
>> ----- Original Message -----
>> From: "MM" <ka1rrw at yahoo.com>
>> To: <amsat-bb at amsat.org>
>> Sent: Wednesday, April 07, 2010 3:06 PM
>> Subject: [amsat-bb] Arecibo on 432 MHz Moon Bounce
>>
>>
>>  Hi all:
>>> Here is a EME event you cant miss.
>>> Dust off your CW key, its time for Satellite, QRP EME.
>>>
>>> The 1,000 foot dish has 60 dBi on 432 mc and 400 watts.
>>> That comes out to be approximately 243,902,443 Million Watts ERP.
>>>
>>> enjoy
>>>
>>> wf1f
>>> www.marexgm.org
>>>
>>> (thanks to KB1MGI for passing on this data)
>>> ... snip ...
>>>
>>
```