[Test-Equipment] RF spectrum analysis

[Dave Brown]

Yaesu FT757 GX II will put out low power down there but there's no access to 
the driver output-just the normal  PA output.
The PA will shut down at more than a watt or two out with continuous 
keydown, maybe less, depending on how low in frequency you want to go.
 Rig has to be 'broadbanded' first, of course. (undocumented black 
pushbutton on pcb behind display)
Dave
ZL3FJ

----- Original Message ----- 
From: "Carl" <km1h at jeremy.mv.com>
To: <garyschafer at comcast.net>; "Discussion of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Tuesday, January 21, 2014 8:59 AM
Subject: Re: [Test-Equipment] RF spectrum analysis


> Is there any older xcvr, especially KW that will TX below 500 KHz at the 
> pre driver stage? Even 1 mw is fine.
> Ive been unable to find the unlock secret for my TS-940 and TS-950SD.
>
> Carl
> KM1H
>
>
> ----- Original Message ----- 
> From: "Gary Schafer" <garyschafer at comcast.net>
> To: "'Discussion of Electronic Test Equipment'" 
> <test-equipment at mailman.qth.net>
> Sent: Monday, January 20, 2014 12:14 PM
> Subject: Re: [Test-Equipment] RF spectrum analysis
>
>
>> One of the best and most economical pieces of test equipment is a ham
>> transceiver such as an older Kenwood TS430. Remove the diode that allows
>> general coverage and you have a continues coverage receiver and signal
>> generator from around 50 kHz to 30 MC.
>>
>> You can use the receiver as a manual tuned spectrum analyzer, signal 
>> level
>> meter, frequency meter etc. You can even measure intermodulation levels
>> using the CW filter.
>>
>> In the transmit mode (be care full not to turn the carrier level up too
>> high) you have a signal generator with very accurate frequency 
>> calibration
>> with variable level although uncalibrated level. Use with an external 
>> step
>> attenuator as a great enhancement.
>>
>> On a limited budget something like this will do a lot for you.
>> I have spectrum analyzers, tracking generators, scopes, signal level 
>> meters
>> various analog and synthesized signal generators etc. But I still often 
>> use
>> the transceiver for quick and easy checks of some things.
>>
>> 73
>> Gary  K4FMX
>>
>>
>>> -----Original Message-----
>>> From: test-equipment-bounces at mailman.qth.net [mailto:test-equipment-
>>> bounces at mailman.qth.net] On Behalf Of David
>>> Sent: Sunday, January 19, 2014 10:54 PM
>>> To: Discussion of Electronic Test Equipment
>>> Subject: Re: [Test-Equipment] RF spectrum analysis
>>>
>>> On Sun, 19 Jan 2014 21:52:47 -0500 (EST), you wrote:
>>>
>>> >&gt; What I'm mostly interested in is ham receiver design, building,
>>> and
>>> >&gt; alignment. So, that would involve looking at the passbands of the
>>> tuned
>>> >&gt; circuits associated with RF amplifiers, mixers, and IF stages,
>>> including
>>> >&gt; crystal or other types of filters. Perhaps 1 kHz to 100 kHz wide
>>> at a center
>>> >&gt; frequency of  around 2 mhz. Of course it would be nice to be able
>>> to look at
>>> >&gt; RF amplifier circuits at up to 30 mHz, as it's the good old HF
>>> region that
>>> >&gt; I'm interested in.
>>> >
>>> >Doesn't it seem like this requirement can be met with a sweep generator
>>> and oscilloscope?
>>> >
>>> >Wayne
>>> >WB4OGM
>>>
>>> I have done this before but it is really only feasible if low accuracy
>>> is
>>> acceptable.
>>>
>>> The sweep generator should have a marker output if any frequency
>>> accuracy is
>>> required but an alternative is to use an oscilloscope which has a gated
>>> timer
>>> counter but that is a rare feature and offhand I do not know of any
>>> modern
>>> oscilloscopes which support it.  The Tektronix 7000 series can and maybe
>>> the
>>> 2247A or the 2465 series with the right options can also.
>>>
>>> Amplitude resolution will be good but the dynamic range will be terrible
>>> without
>>> logarithmic scaling.
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>
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