[ICOM] IC-7100

Tue Jul 30 20:20:22 EDT 2013

Thank you Roger. Excellent discussion.
The Drake SPR-4 is considered to be a solid state R-4B. It is a nice radio, but the AGC action is terrible. Static crashes capture it (in SSB) and the very slow decay de-sensitizes the radio. There are 'fixes', but just no time to mess with it. The AGC is set at different fixed values for the different modes. This is a collectable radio and not only is it 100% mint, it is fully loaded with all the options...

My only real interest anymore is 6M weak signal and 2M and 432. I have a lot of radios as I mentioned and I have a LOT of 6, 2, and 432 converters and preamps.
Listening to very weak signals on 6M scatter, I have never found a combo yet that can beat the 'ole 756PRO. I had an Icom 575H and it was as close as these 2 old (too old??) ears could call. Believe it or not, just for weak signal reception, my 706g hangs right in there as well.
Here in the Florida woods, I have no close by stations and don't do HF contesting.
My personal favorite from both a nostalgic / performance point of view, is my Drake TR6/RV6  with modern JFETs in the front end.

If I thought any of the new radios could hear weak 6M signals clearly that my PRO couldn't hear, I'd start savin'! ha ha

On 6M, I have a long 7 el antenna at 105' , fed with 7/8" hardline. Since I can 'hear' my antenna when it's connected, I feel that I'm at my practical limit on receive sensitivity.
Of course, living 100+ miles from the 'lightning capitol of the USA', limits my weak signal work a LOT more than it did when I lived in Ky.....

Your thoughts???

ron
N4UE

-----Original Message-----
From: Roger (K8RI) <k8ri at rogerhalstead.com>
To: icom <icom at mailman.qth.net>
Sent: Mon, Jul 29, 2013 12:41 am
Subject: Re: [ICOM] IC-7100

On 7/28/2013 6:30 PM, bonddaleena at aol.com wrote:
> OK, you said you did an A/B test, but you never mentioned what you compared 
the 756PRO to.....
>
> I have compared my PRO to:

With an A/B test?

Well, I've owned most of what you mentioned and have fond memories of my 
75A4/KWS1 heating the shack, but regrettably I only did the A/B 
comparison on the FTDX5000MP .As I said, The 756 Pro that appears to 
check out with the spectrum analyzer. is still a good rig, but the 
5000MP beat it out for selectivity, dynamic range and sensitivity.   It 
heard stations the 756 Pro didn't know were there, copied stations that 
were covered up by adjacent QRM and let me talk to stations on a band 
filled with QRN from storm just a few hundred miles away that made copy 
on the 756 Pro difficult.

OTOH the 756 Pro is light, and goes portable quite easily.

But for normal use, without the A/B comparison it seems to be pretty 
good and I like it.
>
> 75A-4 (recapped, aligned, etc)
> 745 (purchased new)
> 761 (serviced by Scott)
> Drake R-4B (3 of them)
> Drake R-4C (with all the Sherwood mods)
> R-390A (well tuned)
> R-388 (6 of these)
> 51J-3
> SPR-4
> R-71A
> Drake 2-B
> Drake 2-C
> Drake TR-4 (5 of these)
> Halli 117 (modded by the ER articles)
> R-1051B
> SX-101A (recapped, etc)
>

The only ones I've not had are the 388, 51J, SPR4 (don't even recognize 
that one, and the R71.

I rebuilt a lot of 101As and a MK-III, but they got too heavey for a guy 
my age.  I still have a 33B with the ceramic 8295A. Sold the HT32Bs so 
have nothing to match it.

OTOH I had several S-lINES AND kWM2S AND 2AS.  I'd like to pick up a 2A 
(same rig, just more crystals) and PS for my shop.
Those old Collins rigs put out cleaner signals than all but a few of 
today's rigs.

> dozens of others, etc, etc
>
> The PRO is still the receiver to beat. Maybe 'cause it was a JA radio that I 
hand carried back from Tokyo???
>

As I said, I still like and use the original 756 Pro, not a II, or III.

> For many years, the receiver has been limited by noise, either man made or 
atmospheric.
> The point of diminishing returns was reached a loooong time ago.

Agreed and with the top end rigs with those fantastic specs, the average 
ham would never be able to tell the difference.

I'd like to see them clean up the signals.  Most SS rigs are running a 
3rd order IM in the low to mid 30s while the old Collins was close to 50db.

I think most hams don't realize that super selectivity and dynamic range 
does nothing to help when the station 10 KHz +/- is splattering or buck 
shoting right in your bandpass.

That's why I'd like them to concentrate on finals instead of a 
sensitivity that is way below the band noise. What good does a 0.1 uv 
sensitivity do on 160, 75, and 40?  The dynamic range does sometimes 
make life livable when a really big signal comes on within 10-20 KHz.

Selectivity?  A good filter, IF shift, and a good notch can work wonders 
that a fantastic selectivity figure will fail to do and there the old 
756 Pro does pretty well on CW.

73,

Roger, (K8RI)
>
> ron
> N4UE
>

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