[1000mp] Twofold Question

[Steve Fraasch]

Bryan:

It probably isn't a big deal unless you're trying to reduce IMD.  Recall that a "good" receiver designer will set the noise figure by setting the RF gain high enough such that the IF gain should not matter.  If you turn your IF gain up, you're just getting that: more IF gain, not more sensitivity.  What you will eventually do by increasing the IF gain is generate IMD in the follow-on stages.

As a practical adjustment, Tim, K3LR suggests turning on the sub-receiver to the same freq as the main receiver, note the difference in S meter readings, and adjust the IF gain accordingly until they're matched.  That assumes that the factory has set the sub-receiver gain properly, which may, or may not be, the case.

I would also suggest setting gain lower if you BCST band DX or operate 160/80.  The ARRL 160 meter contest would be a scenario where you purposely want to set it low, given IMD is probably the main concern.  I can't remember where mine is set, but I think it is "10."  Obviously, using the "IPO" setting to reduce RF gain should also improve IMD performance.  I note that it does when I am cruising thru the AM band.

Also, you may want to try the roofing filter in lieu of the 70 MHz amplifier; that makes a significant improvement to the radio's performance.  Note that using the roofing filter vs. the 70 MHz amplifier are mutually exclusive.

73,

Steve Fraasch, K0SF

-----Original Message-----
From: VE3QN <ve3qn at sympatico.ca>
Sent: Sep 18, 2005 2:45 PM
To: All about Yaesu 1000mp <1000mp at mailman.qth.net>
Subject: Re: [1000mp] Twofold Question

Is it necessary to adjust Menu Item 9-1 at all? As I read the INRAD 
instructions (Step 12) "It is not necessary to adjust menu item 9-1 unless 
you have removed one of our earlier 70 Mhz IF Mods."
So, I left my MkV Field as it was.
73,
Bryan

----- Original Message ----- 
From: "Pete Smith" <n4zr at contesting.com>
To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
Sent: Sunday, September 18, 2005 10:32 AM
Subject: Re: [1000mp] Twofold Question


>A couple of clicks lower than the original.
>
> 73, Pete N4ZR
>
> At 10:30 AM 9/18/2005, you wrote:
>>The archives do not have a search function so I do not have the time to do 
>>the legwalking. When one installs the 70mHz IF Amp
>>mod, what should the setting be for 9-1? I do not remember what my 
>>original setting was.
>>
>>Secondly, is anyone using the dual Heil hm-2? I understand their was a 
>>problem with using those mikes with the Mark V due to
>>the high mic gain settings one had to use with the Mark V. Did Heil make 
>>the improvement?
>>
>>Thanks in advance.
>>73s
>>john
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