Icom ic-7800 sn
Which is a 1 - 1.5 kHz narrowing up and down.Įveryone can view this differently, but in my opinion aĬhange like that is not worth very much. This means you have narrowed your window by 2-3 kHz at best, With the GUF filter, "good performance" BW of the R4C is 6-8 You might as well be using a bottom line receiver like the Performance of a very poor receiver getting rid of that guy. His actual emissions extending down to 3803, you have the If you are onģ800 LSB and a moderately strong signal is on 3806 LSB with The "good performance" BW of the R4C is 8-10kHz, with theĭial frequency in the middle of that window. Having emissions within -4 to -5 and +4 to + 5 kHz of yourĭial setting are problems on all modes, even CW. With the stock 8 kHz filter, moderately strong stations is ONLY good at the BW of the roofing filter!! You can look at the list and see which ones, but The stock frontĮnd in the Drake is OK, on par with the better modern Then the front end sets the dynamic range. We need about 25 dB of suppression outside the signal BW, Passband by about the difference between the 2nd mixerĭynamic range and the front end dynamic us a tinyīit of head room. In order to "hide" the very poor 2nd mixer, the roofingįilter must suppress anything outside of the desired Mixer, the receiver fills up with birdies and carriers as Injection) to dominate the transfer characteristics of the Injection level is set high enough (NORMAL or proper Harmonics of the LO being generated in the mixer tube. Mixer performance requires the mixer be driven hard into and It's a terrible practice to inject a LO signalīelow the operating frequency into a mixer, because good It has this problemīecause Drake injected a 50 kHz LO into a mixer operating on The problem is the second mixer has about the poorestĭynamic range of any mixer in history. Near as good as an Orion (if you can stand the AGC in the I think the Drake R4C is a good receiver, but it is nowhere This is why the fast AGC on the Drake won't work on Too much and then the gain goes through a period of being The filters the receiver overloads in the early stagesīefore the AGC can rise. The AGC problem comes from group delay time You have a very good SSB and CW receiver, except AGC is a Into the receiver, and add a Sherwood 600 Hz CW filter. What you can do is fit Drake transmit LSB and USB filters Skirts just ever so slightly improves the receiver on SSB,Īnd really not anything that you would ever notice on CW. That 8kHz filter with another 6 or 8kHz filter with better Within that 8kHzīandwidth, two or more modest level signals will easily mixĪnd generate a new signal that really isn't there. You canĬonsider the effective BW of the receiver the width of the The problem is the horrible 2nd mixer in the R4C. IMO the GUF1 is not worth bothering with. The GUF1 won't help the R4C a bit for CW. Radio, but we also want todays performance standards. Sorry, I know we all want to relive our early years in ham The shelf as a collectors piece, but I would not consider it competitiveĬlass as is. R4b which are now relegated to back up status.
#ICOM IC 7800 SN UPGRADE#
More than $600 to upgrade a stock r4c for parts alone.
#ICOM IC 7800 SN MODS#
The filters and mods than I did in the rx itself. I had an R4C since new and sold it a year or so ago. One other nit, and that is tuning rate is super fast and it Roofing filters, I suspect you will be very disappointed in its top band (still available from International radio) and certain other mods dependant The r4c is a terrific receiver IF it has the sherwood 600 hz roofingįilter(still available from Bob Sherwood I think), and/or the GUF-1 filter