[Collins] Collins 62S-1 Transverter Downconversion Gain??

[Carl]

Pete, Sam Harris, W1FZJ/W1BU had a 62S1 on loan to evaluate for his CQ VHF 
column in 1962. He said it was deaf on both bands and overloaded bad. This 
was into his S Line.

Ive never heard of any serious weak signal VHF operator using one....for 
very long at least. The Hallicrafters HA2/HA-6 were very popular then.

Carl
KM1H


----- Original Message ----- 
From: "Pete" <zilassoc at la.twcbc.com>
To: <geraldj at weather.net>
Cc: <collins at mailman.qth.net>
Sent: Monday, September 20, 2010 7:25 PM
Subject: Re: [Collins] Collins 62S-1 Transverter Downconversion Gain??


> Jerry,
> The pertent 62S-1 manual info is:
> 1. RX Signal path uses a 6ER5 Triode RF Amp followed by another 6ER5
> triode as a Mixer.
> 2. Noise Figure approximately 4 dB
> 3. System performance is such that: 1.2uV at 2M or 6M yields 10 dB
> S+N/N on AM Signals through a 75S Receiver
> (NOTE: the 75S3 receiver manual spec is 0.5uV yields 10 dB S+N/N)
>
> This information tells me the NF of the cascaded 62S-1/75S3 system is 
> worse
> than the noise figure of either the 62S-1 and the 75S.
> There has to be a net translation loss from VHF to HF in order to match 
> this
> specification.  I'm calculating there should be -8dB conversion loss based
> on these specifications in the manuals.  Interestingly I'm measuring -12 
> dB
> conversion loss.  But, I'd like some confirmation on what it should be.
> What do you think?
> Pete
> K5PZ
>
>
>
> -----Original Message-----
> From: Dr. Gerald N. Johnson [mailto:geraldj at weather.net]
> Sent: Saturday, September 18, 2010 10:32 PM
> To: zilassoc at la.twcbc.com
> Cc: collins at mailman.qth.net
> Subject: Re: Collins 62S-1 Transverter Downconversion Gain??
>
> Shouldn't need much gain, just enough so the 62S-1 RF stage noise sets the
> NF of the system. A better check than gain is the NF of the system done 
> with
> a manual vacuum diode noise source and an AC VTVM on the IF audio output
> with AVC turned off. To much gain introduces unneeded intermod from strong
> signals. But since the 75S NF at 20 meters is probably 8 or 10 dB if the
> system NF is going to get down to 2 dB for 2m and 5 dB for 6m, its going 
> to
> take maybe 15 to 20 dB gain in the 62S-1.
> There should be a detectable (not necessarily on the S-meter) noise rise 
> in
> the IF receiver when the 62S-1 is switched into the circuit. A few dB is
> common, without checking system NF its hard to say how much there should 
> be.
> Some VHF operators would advocate a 10 dB rise and I think in most cases
> that is way too much leading to intermod problems.
>
> What does the 52S-1 use for RF stages in the receive side? I don't have a
> manual on it.
>
> 73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.
>
> On 9/19/2010 12:02 AM, zilassoc at la.twcbc.com wrote:
>> Does anyone know the 50MHz to 14MHz conversion gain or loss of a
>> properly operating 62S-1?  What about from 144MHz to 14MHz?  The
>> manual doesn't state this metric. Thanks for the bandwidth, 73 Pete,
>> K5PZ
>>
>>
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