## FM radio on 15 MHz?

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• Hi, Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz? In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++
Message 1 of 7 , May 10, 2009
Hi,

Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
The ALA1530+SSB is on the roof, sitting close to two FM antennas.

73,
Günter
D-85354 Freising
RX: Perseus ANT: ALA1530+SSB
• theoretically the oszillator signal 80MHz could mix with the FM 95MHz and produce a 15 MHz signal ?? Werner ... theoretically the oszillator signal 80MHz
Message 2 of 7 , May 10, 2009
theoretically the oszillator signal 80MHz could mix with the FM 95MHz and produce a 15 MHz signal ??   Werner

Am 10. Mai 2009 22:43 schrieb Günter Lorenz :

Hi,

Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
The ALA1530+SSB is on the roof, sitting close to two FM antennas.

73,
Günter
D-85354 Freising
RX: Perseus ANT: ALA1530+SSB

• Werner, thank you. As the 80 MHz will not leave the Perseus box, it must be the 95 MHz entering the circuitry at a very high level - can t measure, because my
Message 3 of 7 , May 10, 2009
Werner, thank you. As the 80 MHz will not leave the Perseus box, it must be the 95 MHz entering the circuitry at a very high level - can't measure, because my Perseus stops at 40 MHz ;-)
I'll do some tests with another antenna.

73,
Günter

Von: perseus_SDR@yahoogroups.com [mailto:perseus_SDR@yahoogroups.com] Im Auftrag von Werner Karn
Gesendet: Sonntag, 10. Mai 2009 23:03
An: perseus_SDR@yahoogroups.com
Betreff: Re: [perseus_SDR] FM radio on 15 MHz?

theoretically the oszillator signal 80MHz could mix with the FM 95MHz and produce a 15 MHz signal ??   Werner

Am 10. Mai 2009 22:43 schrieb Günter Lorenz :

Hi,

Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
The ALA1530+SSB is on the roof, sitting close to two FM antennas.

73,
Günter
D-85354 Freising
RX: Perseus ANT: ALA1530+SSB

• Signals are mirrored around 40MHz as center and around zero MHz as center. A signal on 80MHz would have a mirror at zero. A 95MHz signal therefore at -15MHz
Message 4 of 7 , May 10, 2009
Signals are mirrored around 40MHz as center and around
zero MHz as center.
A signal on 80MHz would have a mirror at zero.
A 95MHz signal therefore at '-15MHz' and 15MHz.
I guess you have bypassed your preselector in Perseus .
I've fed a -10dBm signal on 95MHz into Perseus.
Nothing to hear on 15MHz with pres. on but a nice signal with
pres. off.
Even a 0dBm signal gives only a very weak audible mirror signal
on 15MHz with pres. on.

73
Clemens
DL4RAJ

--- In perseus_SDR@yahoogroups.com, Günter Lorenz <glorenz@...> wrote:
>
> Hi,
>
> Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
> In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
> The ALA1530+SSB is on the roof, sitting close to two FM antennas.
>
> 73,
> Günter
> D-85354 Freising
> RX: Perseus ANT: ALA1530+SSB
>
• Gunter, Here s one speculative suggestion for you. I believe the ADC clock is at 80 MHz. Is this correct? 95 - 80 = 15 Henry.
Message 5 of 7 , May 10, 2009
Gunter,

Here's one speculative suggestion for you.

I believe the ADC clock is at 80 MHz. Is this correct?

95 - 80 = 15

Henry.

Günter Lorenz wrote:
> Hi,
>
> Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
> In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
> The ALA1530+SSB is on the roof, sitting close to two FM antennas.
>
> 73,
> Günter
> D-85354 Freising
> RX: Perseus ANT: ALA1530+SSB
>
>
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• My apologies - I have just seen reading thru my other emails that others have already responded.
Message 6 of 7 , May 10, 2009
My apologies - I have just seen reading thru my other emails that others

Henry wrote:
> Gunter,
>
> Here's one speculative suggestion for you.
>
> I believe the ADC clock is at 80 MHz. Is this correct?
>
> 95 - 80 = 15
>
>
>
> Henry.
>
>
>
> Günter Lorenz wrote:
>
>> Hi,
>>
>> Is there any maths for Perseus which would make my local 95.0 MHz FM station appear on 15 MHz?
>> In FM mode with 50 kHz, approx -88 dbm. 95.0 MHz is 70db++ on my FM tuner.
>> The ALA1530+SSB is on the roof, sitting close to two FM antennas.
>>
>> 73,
>> Günter
>> D-85354 Freising
>> RX: Perseus ANT: ALA1530+SSB
>>
>>
>> ------------------------------------
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• ... Yes, indeed! I don t even know why, perhaps because normally I do not note much difference, but in this case - yes, 15 MHz is clean again with Presel on.
Message 7 of 7 , May 12, 2009
> I guess you have bypassed your preselector in Perseus .

Yes, indeed! I don't even know why, perhaps because normally I do not note much difference, but in this case - yes, 15 MHz is "clean" again with Presel on.
Thanks to all who replied, and happy Perseusing!

73,
Günter
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