VK Logger Ham Radio Forum Archive

Hi all

Can any one verify that the IC-910H does or does not put out a brief spike in output power, when TXing on 70cm, and when the RF output control is set to anything below maximum.
I cannot afford to have a spike when it is set to minimum power out (5W according to the manual).

Please, no guessing.

It just occured to me.. the answer is academic anyway.
I cannot use the 910 as a backup to drive the transverters, because it lacks the TX Inhibit line that the 817 has.

Adam
I suggest asking Rex vk7mo. He uses a 910 to drive a 10G transverter. He told me he had no trouble with spikes. He runs the 910 on minimum power on 144.
Cheers



Andrew Davis VK1DA & VK2UH
Sent from my iPhone using Tapatalk

Hi Adam

In my case I do use an IC-910-H on 144 MHz into a DB6NT transverter without any problems from the spike - but this may be because the DB6NT can absorb up to 5 watts continous with a big resistor and the short spike does not worry it. This may or may not be the case with other transverters.

73 Rex

i use my 910h into a vk5eme transverter with the power turned down to minimum and its been fine for years now. the sequencer has a bank of resistors as a dummy load and if there was a short spike it handles it ok.
i have browned the resistors off a bit by accidently not turning the power down once but it didnt damage the transverter

73 from Dave

In my experience if these spikes occur, they are full power; not a small transient spike. As soon as the PA is alive and RF is sent to it, the full power spike occurs before the ALC brings it down to the level the user set.

From what I've experienced (FT857D) and read, it does seem to be more a trait of Yaesu radios than Icom. Perhaps Icom do things differently and ensure the ALC is set and ready before the PA can run up to maximum output?

Even if you are to use a radio well known for transient spikes (FT857D again) it's a simple matter to build a small variable -Volts regulated source to feed the ALC pin on the accessory port to ensure the spikes simply can't happen.

For example: http://www.astromag.co.uk/ft857d/

73 - Rob VK2GOM / GW0MOH

Thank you for the comments.

It wasn't so much the resistors in the pad I was concerned about, (I'd expect they could handle a greater power level, for a brief moment), but the mixers.
These can be quite delicate and sensitive to levels.