FRG 7000 help - Page 1
Forum section: electronics / beginners

author: Jazzman
author_rank: Contributor
timestamp: January 13, 2024, 07:14:17 am
content: Hi all,I've been working on my old FRG7000 which was deaf when I first bought it.The problem I'm currently up against is it doesn't seem to see or hear my signal generator.I have a frequency counter which confirms the signal generator is working, and when I lay the generator's lead over the radio I can tune the radio to wherever I have the generator set to.But when I connect the the signal generator to any of the test points suggested in the FRG7000 handbook I get no response at all.I should add the fact that I bought one of those cheap Chinese signal generators and on connecting it to the FRG got no response at all, thinking it was duff I sent it back and bought a second hand generator, only to discover I still have the same problem.So to sum up, on the FRG instruction it says connect a signal generator to test point 105 and 106 with a frequency of 2.1Mhz which in turn will cause the frg display to change to 900Khz...this does not happen whatever I do, in fact nothing whatsoever happens.Is there a specific way of connecting a signal generator??Any help would e much appreciated.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 13, 2024, 10:07:43 am
content: Quote from: Jazzman on January 13, 2024, 07:14:17 amWhat they mean here is that you should set the FRG to display 900KHz, not that it will change automatically.

author: Jazzman
author_rank: Contributor
timestamp: January 13, 2024, 12:39:27 pm
content: Hi, many thanks for the speedy reply.Sadly I'm still nor getting any change, there's not the slightest flicker on the S meter when adjusting the relevant cores.I should say, I'm getting strong sideband signals from 10 to 80 Mtrs plus MW and LW broadcasts. What I'm really trying to achieve is for the lock light to go out when peaking the Mhz control. If I can just nail this last detail then the receiver is done and fully working, but whatever I do I can't seem to fix this damn light issue.

author: xrunner
author_rank: Super Contributor
timestamp: January 13, 2024, 01:52:54 pm
content: Quote from: Jazzman on January 13, 2024, 12:39:27 pmFollow the yellow brick road. Look at the schematic I attached. If the lamp is lit then it isn't being turned off by Q9. The signal that controls the light goes to Q10 and Q9. See if the signal is changing as you adjust the MHz dial. Some of those cans along the way probably aren't adjusted properly ... or other problems ...

author: wasedadoc
author_rank: Super Contributor
timestamp: January 13, 2024, 02:11:46 pm
content: D2 and D3 are a voltage doubler. A strong enough signal turns on Q9 which robs Q10 of base current and the lamp goes out. Check that voltages on Q9 base, Q9 collector and Q10 base all change as you adjust.

author: Jazzman
author_rank: Contributor
timestamp: January 13, 2024, 06:24:04 pm
content: Thanks for the input guys, it's very much appreciated.Well I'm pleased to say I have it sorted.I ended up with with light going off when T09 on the RF board was screwed right in but so much I lost all signals, and conversely unscrewing brought the signals flooding back and the light staying on. Looking at the circuit drawing I could see how T09 handled both the on going signals but also a feed down to T06 via Q05 and in turn eventually to PL3, so I figured they could be an issue with Q05. Tested it in circuit and got some odd results so chopped it out for a new one.Turned the set back on and with a little adjustment of T09 and T06, have more signals than I know what to do with, and the light goes off every 1Mhz from the top to the bottom.As I said from the start, I have very little technical knowledge but do have a fairly good sense of problem solving.The frequency counter proved invaluable in getting a few things straightened up, but not so much the signal generator as approaching it methodically it seems good hearing is enough to bring it inline. I have gone over it with the generator and found very little to do.Again many thanks for all the info and support.All the best.