[amsat-bb] Re: VHF UHF Rig

[Bruce Robertson]

On Fri, Jul 25, 2008 at 11:32 AM, Andrew Glasbrenner
<glasbrenner at mindspring.com> wrote:
> The TS2000 generates an internal signal (a "birdie") on the downlink of
> SO-50 and AO-27. This signal overwhelms the satellite signal in most cases,
> making it difficult if no impossible to use on those two very popular
> satellites.
>
> 73, Drew KO4MA
>
> ----- Original Message -----
> From: "Terry Dillard" <tdillard at gmail.com>
> To: <AMSAT-BB at amsat.org>
> Sent: Friday, July 25, 2008 9:55 AM
> Subject: [amsat-bb] Re: VHF UHF Rig
>
>
>> Pardon my ignorance, but what the heck is a "birdy problem"?
>>
>> --
>> Terry Dillard, KI4YZI
>> www.ki4yzi.com
>> "Veritas Vos Liberabit"
>>
>>
>> On 7/24/08, Sebastian <w4as at bellsouth.net> wrote:
>>>
>>> Oh boy, and here I just bought a used dual band mobile on the cheap
>>> (no transmit) to take care of the birdy problem.
>>>
>>> Do you have any idea why the birdy would show up on a different
>>> radio?  Could it be a matter of a lack of shielding?  It just doesn't
>>> make any sense to me why a different rig would get that interference
>>> on receive, and even when using a different antenna.
>>>
>>> Others have suggested using a preamp on 440, and turning off the
>>> 2000's internal preamp and lowering the rf gain, therefore using the
>>> preamp to get rid of most of the birdy.
>>>
>>> But I guess I'll find out for sure when my other rig gets here.

I should say that my receiving antennas, though outside, are very
close to my transceiver, maybe 4m away through a wood-frame house.
What I assume is happening is that the signal leaks out of the case of
the TS-2000 and is picked up by the antenna itself. I do use a
mast-mount preamp. I have tried including another preamp before the
input to the rig and so forth, but because I think my problem is
actually at the antenna and not merely in the rig, these solutions
have not worked well.

I'm sure if I added another 30m between the rig and the antenna, the
story would be quite different: then it would be more of an internal
signal which could be swamped by preamps, etc.  I'm also quite willing
to believe that this problem varies from radio to radio.

All that said, I'm still reasonably happy with the TS-2000. I forgot
to mention that it has built-in TNC for 1200 baud and 9600 baud packet
radio (or satellites). There is only one serial port, so you have to
either do computer-controlled doppler tuning or download packets to
your computer, not both. When using the internal TNC for pacsats, I
just ride the RIT control manually.

If anyone has some wisdom about tamping down the SO-50 birdie, I'm all ears.

>>> On Jul 24, 2008, at 7:00 PM, Bruce Robertson wrote:
>>>
>>> > On Wed, Jul 23, 2008 at 11:31 PM, Mike Miller <mmiller at nctc.com>
>>> > wrote:
>>> >> Thinking about selling 847.....Which rig is best for
>>> >> satellite..work.?
>>> >>
>>> >> ICOM 910 H
>>> >> Kenwood 2000
>>> >>
>>> >> opinions ....your 2 cents
>>> >
>>> > I own a TS-2000. The birdie problem on SO-50 and AO-27 is quite real,
>>> > and there is no fix I know of. I find that the birdie is so bad that
>>> > even if I use a different receiver on UHF, I pick up the birdie on it
>>> > as well! So it is a worse radio regarding satellite work than the ICOM
>>> > if you care to work these birds.  However, if you consider the fact
>>> > that a fine HF radio is thrown in at no extra cost, that there is
>>> > continuously adjustable filtering also at no cost, you might prefer
>>> > that trade-off. I'm reasonably pleased with mine.
>>> >
>>> > However, if money were no issue, I would get the ICOM for satellite
>>> > work and a different HF radio with even better characteristics.
>>> >
>>> > HTH,
>>> >
>>> > 73, Bruce
>>> > VE9QRP
>>>
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