Thank you so much Andrew for jumping in. My CMU200 can set the output down low enough. ?How do you minimize leakage for the WFM adjustments? ?
I am going to double check with the oscilloscope when I get back to it tomorrow at the end of the feed line to make sure I¡¯m generating the correct level at the radio end. ?
Another question for you is the RX Total Gain,
Says to set 25db of AF level between 500uV and no signal. ?(Or 30db for HF). ?The 500uV signal is consistently at 8.6db and the adjustment only makes changes on the noise floor when the signal is off. ?So I tried adjusting it so the noise level is 25/30db difference but I can¡¯t get it that far apart. ?I max out the setting at the highest gain and I¡¯m still off a little bit. ?So either something isn¡¯t right with the radio, or I¡¯m not understanding the procedure/setting. ?I am assuming I¡¯m looking for 25 db difference on the AC millivoltmeter and not the S meter on the radio, but not getting the changes I was expecting.
Any input on what I am doing wrong or what the problem could be? ?I will verify with the oscilloscope the SSG signals at the end of feed line disconnected per the footnote, but wondering if you could give any additional clarity.
Thanks,
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On May 1, 2025, at 4:09?AM, Andrew Lenton via groups.io <a@...> wrote:
?
Hi I have replied a fair few of these radios, all with 100% success.
With regards alignment I have never had to pefrom this on received. I have set up the bias on PA transistors after replacement, which is also rare.
Unless you have a professional RF signal generator it is hard to aligned the RX, one reason is when you set levels down at -120dBm you get leakage unless the the signal generator is professional. ?10,000 plus!
The new siglent RF signal generators only go down to -105 dBm fir this reason of leakage.
You also need a decent audio signal generator never use a PC or laptop.
99% of the time, if you need to realign it is because some has twiddled it.
KR
Andrew
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On 1 May 2025, at 03:21, "Craig- KB4RU via " <
gmail.com@groups.io target=_blank>
[email protected]> wrote:
I was planning on making a video of the process once I get the kinks worked out. ?I am learning and this is not an easy radio to work on, and I¡¯m suspecting the service manual has some typos, or I am not understanding something correct. ?
Some of the adjustment parameters are to calibrate the signal meter and power output levels along with the power output meter.?
I finally got through the transmitter, but the receiver has a new variety of challenges. ?I have not found anyone really talk about aligning the 7000s and there is next to no information that I have found from people talking about the process online. ?I talked to a tech who told me it is not easy to do, and the test signals at low levels are the hardest to get right. ?Some spots on the service manual are clear as mud or don¡¯t make sense to me. ?The one I¡¯m working on currently had extensive repairs done, so I¡¯ll probably have to put my good one on to clarify a few points in the service manual. ?It¡¯s entirely possible I have a problem that isn¡¯t obvious that¡¯s complicating the process. ?Hopefully comparing the 2 will help clarify a few spots.
On Apr 30, 2025, at 8:17?PM, HF via groups.io <incorridge@...> wrote:
?
Thanks, Craig!
I was using an online tone generator and an oscilloscope to look at the amplitude.? It also had a lot of noise on it; possibly an AM station picked up along the way and maybe provided by the laptop itself.? So I'm going to give it another go with a real signal generator and, as you suggested, shielded cable up to the MIC connector.
I'm thinking of skipping some of the other steps.? One set seems to be meant to calibrate the radio's internal output power meter; that seems accurate enough already.? But I don't know how to check if the APC is working correctly.? The ALC bar is orange and at half scale.? If APC was reducing my TX power due to excessive drive, the ALC bar would have some red on it, right?
Cheers,
Halden VE7UTS
